Cranial ultrasound on neonatal intensive care units is generally performed by intensive care physicians, but radiologists often provide this crucial bedside test to children on specialist paediatric cardiac intensive care units. On a paediatric cardiac intensive care unit, complex congenital cardiac conditions are commonly encountered in both pre- and postoperative scenarios, often with the use of extracorporeal membrane oxygenation (ECMO), which both increases the risks of a number of neurologic complications and results in significant changes in vascular physiology. The aim of this pictorial essay is to discuss cranial ultrasound technique, demonstrate the changes in Doppler flow profiles resulting from veno-arterial extracorporeal membrane oxygenation and congenital cardiac conditions, and illustrate commonly encountered intracranial complications of extracorporeal membrane oxygenation support in congenital cardiac care. In the United Kingdom, most cranial ultrasound (US) examinations are performed in the context of prematurity, by neonatal intensive care physicians. However, in specialist paediatric cardiac surgical centres, radiologists often provide this crucial bedside imaging service. In these units, veno-arterial extracorporeal membrane oxygenation (ECMO) is commonly used as a form of periprocedural support in neonates with particularly complex congenital heart diseases.These children sometimes sustain significant neurologic complications, both from their underlying cardiac disease and subsequent surgical intervention, as well as from anticoagulation and the ECMO support itself. A two-decade review of neurologic events related to ECMO in The Netherlands reported cranial ultrasound abnormalities in 17% of patients, most frequently haemorrhage (8.8%) and ischaemic stroke (5%), with higher frequencies of complications in veno-arterial ECMO and an interesting predominance of left-sided pathology [Extracorporeal membrane oxygenation support is not compatible with MRI, and at times safe transfer to the CT scanner is not possible. Outside of the few centres employing mobile CT units, this leaves ultrasound as the only immediately available modality. The aim of this pictorial review was to illustrate the US appearance of common and less common intracranial pathologies encountered in neonates and infants with congenital heart diseases, before, during and after receiving ECMO support.In veno-arterial ECMO, blood is diverted from the child’s systemic venous system through an external membrane for gaseous exchange, and then the oxygenated blood is returned to the child’s arterial system at systemic arterial pressure, thus facilitating both oxygenation and systemic vascular output Fig. . The catAnticoagulation is required to prevent the formation of thrombi within the ECMO circuit. Together with altered haemodynamics and damage to, or occlusion of, the neck vessels, there is an increased risk of neurologic complications, including intracerebral haemorrhage and ischaemic/embolic infarction .Cranial US is a safe, portable technique capable of real-time structural assessment and colour phase and spectral Doppler imaging of intracranial arterial and venous flow. It is often used to provide baseline imaging before cardiac surgery, as a bedside monitoring tool after initiation of ECMO support, and for daily follow-up of evolving pathology. If further characterisation of lesions detected on US is required or clinical suspicion persists despite a negative US, CT is the cross-sectional imaging modality of choice because the ECMO equipment is not compatible with the MRI scanner. After ECMO therapy is withdrawn, MRI is the follow-up imaging modality of choice. There are, of course, limitations to cranial US, with the diagnostic quality of cranial US being highly operator-dependent and with reduced visualisation of the posterior fossa and convexity regions. Furthermore, ultrasound has reduced sensitivity and specificity for pathologies other than major haemorrhage compared to both CT and MRI –6.The anterior fontanelle provides the largest cranial sonographic window for both coronal and sagittal image acquisition and is usually the last of the fontanelles to close (50% close by 16 months of age) . In addiIn a normal brain, low-resistance waveforms should be evident within both intracranial internal carotid arteries with vertical systolic upstrokes (short acceleration time) and constant forward flow throughout diastole Fig. . In a chIntracranial haemorrhage is the most frequent neurologic complication in neonates receiving ECMO support , the majIntracranial sites of haemorrhage visible on ultrasound include the germinal matrix, ventricular system, cerebral and cerebellar parenchyma and extra-axial spaces . On ultrasound, haematoma normally appears as echogenic (bright) space-occupying material Fig. , and depIntraventricular haemorrhage can obstruct arachnoid granulation tissue, resulting in communicating hydrocephalus Fig. , at timeAs haematoma begins to liquefy, particularly in the extra-axial spaces, it can become hypo- or even anechoic, often containing echogenic debris or even a debris–fluid level Fig. . Serial After haemorrhage, the second most common major neurologic injury sustained by infants on extracorporeal membrane oxygenation is ischaemia, whether secondary to underlying pathology , complications of surgery or initiation of ECMO support  or a combination of factors. On ultrasound, regions of established ischaemic infarction appear hyperechoic, with loss of grey–white matter differentiation occasionally appreciable on high-frequency imaging. Infarcts often occupy characteristic vascular territories but are occasionally more localised . If small and localised they can be difficult to distinguish from focal haemorrhage, in which case correlation with cross-sectional imaging  is useful Fig. .Fig. 11AVenous infarcts typically occur in a non-arterial distribution and are most frequently visible as hyperechoic regions in the thalami or basal ganglia Fig. . InfarctCerebral energy depletion, described in conditions including infarction and prolonged hypoxic–ischaemic encephalopathy, can lead to necrosis of cortical lamina. This can be associated with diffuse, focal or punctate cortical haemorrhage and can later calcify . The appPeriventricular leukomalacia is a white matter injury related to watershed ischemia of the immature cerebrovascular system, frequently seen in premature neonates. There are two different forms: diffuse and cystic. The diffuse form can be more difficult to detect on ultrasound and might require evaluation with MRI . The cysLenticulostriate vasculopathy is thought to be caused by thickening of the lenticulostriate branches of the middle cerebral arteries and leads to branching echogenic structures becoming visible within the basal ganglia on cranial US. The specific pathogenesis is not fully understood , althougSevere diffuse hypoxic–ischaemic encephalopathy in neonates initially results in a central pattern of damage, involving deep grey matter , but with prolonged ischaemia, the cortex can also become involved. Ultrasound might initially appear normal or demonstrate a mild global increase in cerebral echogenicity with or without diffuse swelling obliterating the cerebrospinal fluid spaces. Increased echogenicity of the thalami Fig.  suggestsCranial US is a safe, portable technique allowing screening prior to, and monitoring whilst on, extracorporeal membrane oxygenation support. Whilst ultrasound is the first-line imaging technique in these children, significant limitations (particularly in the setting of suspected acute ischaemia) leave CT as the modality of choice for confirming and demonstrating the extent of significant pathologies whilst a child is on ECMO support, particularly when important treatment decisions are required, often including the decision as to whether to continue ECMO support.


Arabidopsis thaliana diploids and their derived autopolyploids to quantify the degree of inter-genome coordination of transcriptional responses to nuclear whole genome duplication in two different organs . We show that nuclear and organellar genomes exhibit highly coordinated responses in both organs. First, organelle genome copy number increased in response to nuclear whole genome duplication (WGD), at least partially compensating for altered nuclear genome dosage. Second, transcriptional output of the different cellular compartments is tuned to maintain diploid-like levels of relative expression among interacting genes. In particular, plastid genes and nuclear genes whose products are plastid-targeted show coordinated down-regulation, such that their expression levels relative to each other remain constant across ploidy levels. Conversely, mitochondrial genes and nuclear genes with mitochondrial targeting show either constant or coordinated up-regulation of expression relative to other nuclear genes. Thus, cytonuclear coordination is robust to changes in nuclear ploidy level, with diploid-like balance in transcript abundances achieved within three generations after nuclear whole genome duplication.Polyploidy is hypothesized to cause dosage imbalances between the nucleus and the other genome-containing organelles (mitochondria and plastids), but the evidence for this is limited. We performed RNA-seq on  Plant cells must coordinate the activities of three distinct genomes—those of the nucleus, plastids and mitochondria, and failure to do so is associated with disruption of such fundamental metabolic processes as respiration and photosynthesis ,2,3,4. CDisruptions to cytonuclear interactions has long been thought to be a central challenge faced by polyploids ,10,11,12Polyploidy also increases nuclear genome content without directly altering the dosage of the cytosolic genomes, potentially causing dosage imbalances ,9,12. BeNuclear genes whose products are targeted to organelles are among the first to return to single copy following whole genome duplication (WGD) . This haLeucanthemum. They showed that although the copy number of plastid-encoded psbA decreased relative to that of the nucleus-encoded psbO with increasing ploidy, the ratio of transcript abundances for the two genes remained constant. This indicates that for these two interacting proteins, the nuclear and plastid genomes are able to coordinate expression levels to compensate for changes in relative gene dosage. Similarly, in the case of RuBisCO, they showed that rbcL expression per gene copy is upregulated in the polyploids, which also suggests some coordination in response to WGD. In contrast to psbA/psbO, however, the increase in rbcL expression did not keep pace with the increase in rbcS expression, indicating that dosage compensation was incomplete. Thus, mechanisms of dosage compensation appear to be acting in both cases, but with variable degrees of effectiveness. This could reflect a higher tolerance for transcriptional dosage imbalances in some complexes vs. others ) were calculated by first calculating reads per kilobase , summing RPK values for all genes, then dividing individual RPK values by the sum of all RPK values divided by 1 million.ng HTSeq  with theStatistics: TPM ratios  were compared among targeting classes or genomes using Kruskal–Wallis tests, followed by Dunn’s multiple comparisons tests with Benjamini–Hochberg adjustments for multiple comparisons. Total read count ratios were compared by one-way ANOVA followed by t-tests with Bonferroni correction for multiple comparisons. Correlations between expression estimates from poly(A)-selected libraries and ribosomal RNA-depleted libraries (see below) were assessed by one-way ANOVA. All statistical tests were implemented in R. Dunn tests were implemented using the FSA package for R (https://github.com/droglenc/FSA). To assess the utility of our polyA-selected RNA-seq libraries for quantifying organellar expression, we compared the leaf organelle expression profiles of our libraries to ribosome-depleted libraries acquired from the SRA . BioProject PRJNA437291 was a study of the effects of herbivory . The libWe performed qPCR to quantify plastid and mitochondrial genome copy number relative to nuclear genome copy number. Using genomic DNA from diploid and tetraploid rosette leaves (extracted from the same plants used for RNA-seq), we amplified plastid-encoded RbcL (ATCG00490) or mitochondria-encoded ribosomal 26S (ATMG00020), and normalized their copy number to the geometric mean of two nuclear genes (lipid-transfer protein [AT2G10940] and protein phosphatase 2A [AT1G69960]). The qPCR data indicate that plastid copy number decreased slightly per nuclear genome (0.76-fold ± 0.18 SE) in tetraploids vs. diploids, whereas mitochondrial copy number remained constant (1.01-fold ± 0.25 SE) . Thus, thttp://cymira.colostate.edu/). In all three cytotypes  and both organs , genes with plastid- and dual-targeted products had the highest median expression, and genes with unknown targeting were expressed at the lowest levels  for all genes in the most recent annotation of the Arabidopsis genome and plotted expression levels by subcellular targeting using targeting assignments from the CyMIRA database  . In both organs, the expression of genes whose products have unknown or non-organelle targeting (CyMIRA targeting designation of “other”) increased with WGD , whereas the expression of genes whose products are targeted to plastids generally decreased (ratio < 1). Genes with mitochondrial targeting exhibited intermediate responses, with the median falling just above 1 in most cases. To assess transcriptional responses to WGD for the different targeting classes, we calculated ratios of TPMs  for each gene, and plotted the distributions of these ratios by targeting category . DistribThis indicates that the fraction of total nuclear transcription targeted to plastids decreases with increasing ploidy. This finding is also supported when we sum read counts from all nuclear genes encoding plastid-targeted proteins and divide this by the sum of read counts for all protein-coding nuclear genes . Expression from nuclear genes with plastid-targeted products became a smaller fraction of total nuclear expression with increasing ploidy A,C. NotaConsequently, as ploidy increases, relative transcriptional output within the nucleus increases for genes with mitochondrial targeting and decreases for genes with plastid targeting. These expression patterns closely reflect genome copy numbers . Namely,To see if this restructuring of the nuclear transcriptome reflects coordination with organellar transcription, we next looked to see if WGD caused shifts in the overall level of transcription derived from each of the three genomes in the cell . Before doing this, however, we first assessed how accurately read counts from our RNA-seq libraries reflect actual expression levels for organellar genes.Our RNA-seq libraries were generated from polyadenylated transcripts, but transcripts from organellar protein-coding genes are not always polyadenylated , and genAs expected, the main difference between the two library types was that organellar TPMs were higher in rRNA-depleted libraries than in poly(A)-selected libraries . As a reTo assess if WGD alters the relative levels of transcriptional output from organelles vs. the nucleus, we examined the ratio of organelle expression to nuclear expression. Similar to above , we summWe see a similar pattern when we calculate TPM ratios for each genome . PlastidTogether, the data suggest that the nucleus and organelles are able to coordinate expression responses to nuclear genome doubling within the first few generations post-WGD . If such coordination is in fact the case, we would expect the ratio of organelle-encoded transcription to organelle-targeted nuclear transcription to remain relatively constant across ploidy levels. Indeed, the ratio of plastid-encoded transcription to plastid-targeted nuclear transcription is stable across ploidy levels in both organs . Thus, oIn contrast, although the expression of mitochondrial genes and nuclear genes encoding mitochondrial proteins both increase to some extent, the ratio of mitochondrial transcripts to mitochondria-targeted nuclear transcripts also increases with ploidy . This geAmong the nuclear genes with targeting to the plastid or mitochondria or both (4268), 910 encode proteins that are classified in the CyMIRA database as interacting with organellar proteins (they are components of chimeric protein complexes), RNA or DNA . Of thesWe next analyzed transcriptional responses to WGD within chimeric organellar protein complexes  A–C. For In the chimeric complexes, organelle-encoded and nucleus-encoded subunits show similar, highly uniform responses , comparable to the entirely nuclear-encoded subunits of OXPHOS II. These patterns are consistent with robust, inter-genome coordination. The preceding analyses were based on relative expression estimates . Such relative measures report the fraction of total transcripts contributed by a given gene , but doTo determine how absolute transcript abundance responds to WGD, we employed an exogenous spike-in strategy that enabled us to estimate absolute expression levels (transcripts per gene copy and transcripts per cell) as described previously  and repoIt has often been speculated that WGD disrupts the coordinated functioning of nuclear and cytoplasmic genomes, both by disrupting co-evolved complexes , and by disrupting inter-genome dosage balance. Several lines of evidence support the conclusion that the genes encoding chimeric protein complexes in organelles have co-evolved , and thaHere, we show that nuclear and plastid genomes exhibit coordinated dosage responses to WGD in nascent autopolyploids. Specifically, plastid genes and nuclear genes whose products are plastid-targeted exhibit coordinated reductions in relative expression (TPMs). Consequently, the ratio of plastid gene expression to plastid-targeted nuclear gene expression remains constant across ploidy levels. Additionally, nuclear genes with plastid-targeting exhibit more uniform responses to WGD than do other nuclear genes, which is indicative of constraints on relative transcript dosage between the nucleus and plastid. Finally, plastid-encoded and nuclear-encoded subunits of chimeric protein complexes exhibit equivalent responses to WGD. Thus, even though the plastid genomes are not directly duplicated themselves, plastid genes maintain balance in transcript stoichiometry with their nuclear partners.Together, these observations support the assertion that coordination of transcription between the nucleus and plastid is important, and that such coordination is maintained, even in the initial stages (within the first three generations) after nuclear genome duplication. Thus, there appear to be robust mechanisms in place to maintain balanced transcriptional output between the nuclear and plastid compartments, even in the face of altered nuclear dosage resulting from WGD.In contrast, the maintenance of transcriptional balance between the nucleus and mitochondria following WGD does not appear to be quite as robust, such that the relative expression of nuclear genes with mitochondria-targeting decreases relative to that of mitochondrial genes following WGD . But eveTo some extent, it is not surprising that the different cellular compartments exhibit coordinated transcriptional responses to WGD. The nucleus and organelles are in intimate communication via anterograde and retrograde signaling, and all known transcription factors regulating organelle transcription are encoded in the nucleus . In factFurthermore, the numbers of plastids and mitochondria per cell vary widely among tissue types and developmental stages ,8,9,38, Several lines of evidence suggest that doubling the nuclear genome would not cause significant disruption of cytonuclear interactions. First, organelles exist in dozens to hundreds of copies per cell, each with several copies of their genome . Thus, dGlycine [Second, the number and/or volume of chloroplasts per cell often increases with WGD ,40,41,42Glycine  among otGlycine . Given tGlycine . Consistent with these observations, we find that the copy number per cell of both plastid- and mitochondrial genomes increased with WGD . In the Leucanthemum ploidy series. The fact that we still observe coordinated expression responses between the nucleus and plastid, therefore, indicates transcriptional regulation is involved in cytonuclear coordination, though perhaps only within the nucleus.Consequently, any change in relative genome dosage produced by WGD is at least partially offset by increased plastid and mitochondrial DNA replication. On the organellar side, therefore, the maintenance of transcriptional balance we observe here may not, in fact, be due to transcriptional regulation per se, but due to an increase in organelle genome number. However, the extent to which organelle number increases with ploidy varies by species and tissue type ,41, and A limitation of the present study is that most regulation of organellar gene expression occurs post-transcriptionally . As a coArabidopsis thaliana. This suggests that cells possess robust mechanisms to rapidly balance transcriptional outputs among the different genomes following WGD. One of these mechanisms is a compensatory increase in mitochondrial and plastid genome dosage, but additional layers of control at the level of transcription likely exist to maintain coordination between the different cellular compartments.Our study provides evidence that diploid-like transcriptional balance between the nucleus, mitochondria and plastids is largely preserved in the first generations after nuclear genome duplication in


Peripheral nerve injuries result in the loss of the motor, sensory and autonomic functions of the denervated segments of the body. Neurons can regenerate after peripheral axotomy, but inaccuracy in reinnervation causes a permanent loss of function that impairs complete recovery. Thus, understanding how regenerating axons respond to their environment and direct their growth is essential to improve the functional outcome of patients with nerve lesions. Schwann cells (SCs) play a crucial role in the regeneration process, but little is known about their contribution to specific reinnervation. Here, we review the mechanisms by which SCs can differentially influence the regeneration of motor and sensory axons. Mature SCs express modality-specific phenotypes that have been associated with the promotion of selective regeneration. These include molecular markers, such as L2/HNK-1 carbohydrate, which is differentially expressed in motor and sensory SCs, or the neurotrophic profile after denervation, which differs remarkably between SC modalities. Other important factors include several molecules implicated in axon-SC interaction. This cell–cell communication through adhesion  and inhibitory molecules  contributes to guiding growing axons to their targets. As many of these factors can be modulated, further research will allow the design of new strategies to improve functional recovery after peripheral nerve injuries. Peripheral nerve injuries may have devastating consequences, as they result in the loss of the motor, sensory and autonomic functions of the part of the body innervated by the injured nerve or trunk. Following peripheral nerve injury, neurons are disconnected from their target organs and initiate a regenerative response. Axotomy triggers molecular and cellular changes in the neuronal body which lead to the activation of regeneration associated genes. In this state, there is a downregulation of neurotransmitter-related proteins, whereas the expression of genes involved in cell survival and neurite outgrowth is increased ,2. SimulThe activation of the transcription factor c-jun triggers this conversion to the repair state , which iThe ability of peripheral neurons to regenerate after axotomy is crucial for restoring lost functions, but it is usually not sufficient to ensure adequate functional restitution. Successful recovery also requires the specific reinnervation of target organs by appropriate axons, and this is mainly determined by the type and site of lesion . In crusDespite increasing understanding of the axonal regeneration process, knowledge about specific reinnervation is still scarce. Is there a universal mechanism determining specificity during axonal regeneration? How do neurons respond to environmental cues leading to preferential direction? What is the implication of SCs in this process? Answering these questions will be essential to design strategies that promote specific regeneration and, thus, improve effective recovery after a nerve lesion.Plenty of studies have been performed on treatments to improve axonal regeneration after peripheral nerve injury, either by administering different drugs, adding trophic factors, gene therapy approaches, applying activity-dependent therapies or increasing the intrinsic growth capability of neurons  ,36,37,38Although there is a consensus on the existence of PMR, the accuracy of regenerating motor axons can be modulated depending on the experimental conditions. Brushart described that after transection and repair of the rat femoral nerve proximal to its bifurcation, significantly more motoneurons projected their axons to the muscle branch than to the cutaneous branch both in juvenile and adult rats, even if the repair was intentionally misaligned . InteresThe PMR phenomenon has given rise to the question of whether the pathway preference originates from signals arriving from the target organs or from the pathway itself. Therefore, in an attempt to better understand the nature of this process, subsequent studies introduced different variations to this model. Contact with target organs can be denied by transecting both distal branches and ligating the proximal stumps, resulting in an absence of preference in the adult rat ,40 or evEven though the causative mechanisms of PMR are unknown, evidence strongly indicates that this process occurs in two phases in the femoral nerve. During the first 2 to 3 weeks, motor axons grow into both distal branches, extending multiple regenerating branches ,49,50,51It is undeniable that SCs can influence specific regeneration, especially when contact with end organs is prevented  or in juExtensive evidence suggests that SCs associated with motor axons have different markers and expression patterns than SCs associated with sensory axons A,B, and Altogether, L2/HNK-1 carbohydrate and NCAM can be considered specific markers of muscle and cutaneous nerve branches, respectively. The molecular identity of the SCs and, particularly, the regulation of these markers is determined not only by the classical division between myelinating and nonmyelinating SCs, but also by their association with motor or sensory axons. Thus, while NCAM is mostly found in the cutaneous branch because it is expressed in sensory nonmyelinating SCs, L2/HNK-1 is found in the muscle branch because it contains motor SCs. How this phenotypic heterogeneity influences regeneration is a complex issue, and further research is essential to understanding it.The expression profile of neurotrophic factors also differs between motor and sensory SCs B.It was described that intact ventral roots predominantly express PTN, VEGF-1 and IGF-1, whereas cutaneous nerves mostly express BDNF, NT-3, HGF and GDNF. After denervation, the expression of these trophic factors also differed between sensory and motor SCs, with PTN and GDNF being strongly upregulated in ventral roots, and NGF, BDNF, VEGF-1, HGF and IGF-1 mainly in cutaneous nerves . The regRecently, the SC neurotrophic profile was found to vary not only by the modality of the associated axons, but also by their central-peripheral location . In an eOn the other hand, IGF-1 and VEGF were limited to the periphery, where their expression was significantly higher in cutaneous than in muscle nerves. In agreement with previous studies, PTN was found to be motor-specific , being eDoes this characteristic pattern of neurotrophic expression play a role in PMR? This issue has been more difficult to solve, since some modality-specific factors do not necessarily promote the regeneration of their modality-matched axons. A clear example is BDNF, a trophic factor expressed by denervated sensory SCs ,58, whicAfter nerve injury, gene expression in SCs is dramatically changed. Hundreds of genes involved in cell cycle, cell proliferation, immune cell function, synaptic structure and neuron function, among others, are differentially regulated after axotomy ,10,11,12It has been suggested that the phenotypic identity of motor and sensory SCs can be maintained through several cell divisions, since the pattern of growth factor expression of SCs from the ventral and dorsal roots was partially preserved in vitro for 2 weeks . This isThe phenotypic memory of the SCs after denervation might play a role in PMR, since graft modality used to repair a nerve resection influences the outcome of axonal regeneration. While some studies could not find improved motor regeneration when the femoral or the facial nerve were repaired with modality-matched grafts ,69, otheThis is also in line with a recent study that demonstrated that cultured neurons extend significantly longer neurites towards their phenotype-matched SCs. Nonetheless, if these muscle and cutaneous nerve-derived SCs were previously treated with GDNF, the phenotype mismatch was overcome, and both motoneurons and DRG neurons elongated neurites to the same extent, independently of the cocultured SC origin . The pos−/− resulted in the absence of PMR in the femoral nerve 6 weeks after transection. Removing PSA enzymatically in wild type mice had the same effect, strongly suggesting a major role of this molecule in specific regeneration. Sprouting of regenerating axons was maintained more distally in NCAM−/− than in wild type mice, which indicates that misdirected motor axon collaterals cannot be effectively pruned in these animals. Since PSA decreases adhesive interactions in the distal stump mediated by laminins and L1, the lack of this glycan might result in increased growth-related signals that surpass the pruning cues [Interactions between regenerating axons and SCs through adhesion molecules play an important role in guiding axons to their target organs A. One ofing cues .In agreement with these results, it was demonstrated that some nerves that do not upregulate PSA after axotomy, such as the obturator and genitofemoral, do not show PMR either. Furthermore, electrical stimulation was able to upregulate this adhesion molecule in the femoral and obturator, but not in the genitofemoral nerve. In both nerves with increased PSA, there was a parallel enhancement of PMR, whereas the genitofemoral did not exhibit motor preference in any condition, supporting the importance of PSA . DespiteAlthough PSA might not be a major determinant for specific regeneration, diverse approaches targeting its pathway achieved a modest effect enhancing PMR and slightly clarified its potential mechanism of action. Using organotypic cultures of the spinal cord and DRG explants, the low molecular weight fibroblast growth factor 2 (FGF-2) was found to be a promising factor selectively promoting motor neurite outgrowth. Its effects were shown to be PSA-dependent, since enzymatically blocking PSA with endoneuraminidase reverted the positive effect of FGF-2 on neuritogenesis. Moreover, PSA-NCAM was found to be interacting with FGFR-1, the main receptor of FGF-2 in the nervous system. Thus, the authors hypothesized that FGF-2 favors interactions between FGFR-1 in SCs and PSA-NCAM in motoneurons . In vivoThe enhancement of PMR has been tested with other adhesion-related molecules, such as the HNK-1 carbohydrate, the neural cell adhesion molecule L1 or the close homolog of L1 (CHL1). Since L2/HNK-1 was shown to be differentially expressed by motor axon-associated SCs , an HNK-Altogether, evidence suggests that axon-SC intercommunication has a relevant role in the regulation of specific regeneration. So far, direct contact through adhesion molecules has received substantial attention, although the mechanisms and the exact interactions determining their influence in PMR are still poorly understood. Nonetheless, there are other axon-SC communication pathways, such as neurotransmitters released by growth cones D. SCs haDuring Wallerian degeneration, myelin breakdown results in the exposure of growth inhibitory molecules such as myelin-associated glycoprotein (MAG) ,92. In tOther inhibitory molecules which are relevant in peripheral nerve regeneration are chondroitin sulfate proteoglycans (CSPGs), extracellular matrix components that are upregulated after nerve injury . In the Thus, inhibitory molecules influence regeneration after nerve injury and, due to their differential effect on motor and sensory neurons, might also participate in the regulation of preferential reinnervation.Electrical stimulation (ES) has been repeatedly demonstrated to improve axonal regeneration after nerve injury (for review see ). Al-MajThis accelerated axonal regeneration was found to correlate with an early upregulation of BDNF and its receptor, trkB , which iMost studies have been focused on the effect of ES on neurons, but the application of electrical stimuli to the nerve affects both neurons and non-neuronal cells, i.e., SCs, fibroblasts and endothelial cells. Recently, it was shown in vitro that ES influenced SC morphology and orientation. These prestimulated SCs were able to promote neurite outgrowth when cultured with unstimulated neurons. Increased neuritogenesis was also achieved using only the conditioned medium from the electrically stimulated SCs , a fact After peripheral nerve injury, guiding axons back to their original target organ remains a major problem hindering complete functional recovery. Axonal regeneration is a complex process in which several components are involved. Hence, understanding the interactions between axons and their environment is essential to improve specific regeneration. Among the several factors influencing this process, target organs are perhaps the most relevant, either by their supply of trophic factors, or by direct contact with axons after reinnervation, which might determine the pruning of misdirected collaterals. However, many other factors have emerged as candidates that regulate preferential regeneration. SCs show modality-specific characteristics that can influence their interaction with regenerating axons. They are a major source of neurotrophic factors in the nerve, but they can also undergo direct communication through adhesion molecules, such as PSA or HNK-1, or even respond to neurotransmitters released by regenerating growth cones. Many of these specific cues and interactions can be modulated to achieve better and more accurate regeneration after axotomy and, thus, improve the functional recovery of patients suffering nerve injuries.


Multi-dimensional trait mechanisms underlying community assembly at regional scales are largely unclear. In this study, we measured leaf economic, hydraulic and anatomical traits of 394 tree species from tropical to cold temperate forests, from which we calculated the leaf trait moments  using community-weighted methods. Economic and hydraulic traits were decoupled at the species level, but coupled at the community level, and relationships between leaf traits in observed communities were stronger than that in null communities, suggesting that the adaptive mechanisms of plant species may be different. Furthermore, leaf economic traits were distributed more evenly across species occupying communities with lower temperature and precipitation, whereas hydraulic traits were distributed more evenly under lower water availability. This suggests that limiting similarity of specific leaf traits within communities would be enhanced when related-resources are limited, and highlights the independent assembly of leaf economics and hydraulic traits in terms of functional evenness. Importantly, the moments of leaf economic and hydraulic traits of observed communities explained more variation in ecosystem productivity than that of null communities, indicating ecosystem productivity depended on trait-based community assembly. Our results highlight the principles of community assembly regarding multi-dimensionsional traits in natural forests at a regional scale. How plant communities assemble and persist has been a fundamental question of ecology , and traRelationships between pairs of leaf traits  at the species level are well-explored, but can arise for varying reasons . First, Assembly of different plant species within communities could alter the relationships between economic and hydraulic traits at the community level. Accordingly, trait-trait relationships established across species of varying communities could potentially be different than trait-trait relationships at the community level . Indeed,The niche-based theory of community assembly proposes that niche differentiation is the basis of species coexistence, and each species can occupy a unique niche within a stable community in the long run . When esTraits involved in the physiological functioning of leaves are fundamental in determining species growth capacities in their given environments, and by extension the productive capacity of the ecosystem. Indeed, plant traits have a close linkage with ecosystem productivity, and ecologists are eager to incorporate plant traits into ecological models to improve their predictions . For exaIn this study, we explored the principles of community assembly in natural forests using multi-dimensional trait analyses. Specifically, we tested two hypotheses: (1) economic-hydraulic traits are strongly coordinated at the community level but decoupled at the species level, and (2) leaf hydraulic traits are distributed more evenly under environments with lower water availability. We then explored whether and how trait-based community assembly determines ecosystem productivity. To test the above hypotheses and answer the aforementioned uncertainties, we measured nine leaf functional traits, including leaf economic, hydraulic and anatomical traits of 394 species of tropical to cold temperate forests.Nine typical forests were selected along the 3700-km north-south transect of China (NSTEC), and they were designated as Jianfengling (JF), Dinghu Mountain (DH), Jiulian Mountain (JL), Shennongjia (SN), Taiyue Mountain (TY), Dongling Mountain (DL), Changbai Mountain (CB), Liangshui (LS), and Huzhong (HZ) . These fThe field survey was conducted from July–August 2013, the peak period of growth for all forests. Sampling plots were located within well-protected national nature reserves with relatively continuous vegetation that is representative of the given forest types. Four experimental plots (30 m × 40 m) were first established in each forest. Plant height and diameter at breast height of all individuals within plots were measured to estimate leaf biomass . In addition to collecting tree species within the sampled community, tree species around the community were also collected, which covered almost all the tree species that could inhabit the sampled community. Sampling outside of communities allowed us to assess for differential trait distributions that may arise within versus across communities.n = 20–30) were collected from four healthy trees and mixed as a composite sample, and then the leaf samples were divided equally into three parts each with approximately 10 leaves. Leaves from one part were used to measure leaf size, dry weight and nitrogen concentration, from another were immediately stored in a cool box with ice and then into the refrigerator to measure chlorophyll concentration, and the last part were cut into small pieces (1.0 cm × 0.5 cm) along the main vein and fixed in formalin-acetic acid-alcohol  to measure hydraulic and anatomical traits  and leaf nitrogen content (N), and we additionally determined leaf chlorophyll content (Chl). After sampling, leaf size was measured using a scanner  and Photoshop CS software , then these leaves were subsequently dried to constant weight in an oven to measure leaf dry weight, SLA was the ratio of leaf size to leaf dry weight . All dri2). In each image, the number of stomata in each photo was recorded, and stomatal density (d) was defined as the number of stomata per leaf area. Five stomata were selected for measurement of stomatal length and width using MIPS , and stomatal size (s) was the area of an ellipse calculated from dimensions of major axis complex length and the minor axis complex width, including the pore size within. Stomatal area fraction (f) was the proportion of total stomatal area, calculated as the product of stomatal density and size, to leaf area.Stomatal and venation traits mechanistically influence leaf hydraulic function, and these two trait categories are often strongly coordinated with each other , therefoLeaf anatomical traits play important roles in gas exchange and water transport . SpatialAbbreviations, units of nine leaf functional traits, and trait profiles are summarized in 2 ranged from 0.52 to 1) were used in this study.Total leaf biomass of each individual was calculated using species-specific allometric regressions based on measured values of diameter at breast height and tree height, and then leaf biomass of each species within plots were calculated. These equations were obtained from the Chinese Ecosystem Research Net database , includiThe mass ratio hypothesis  predictspi was the relative leaf biomass of ith species, and Traiti was the specific leaf functional trait of the ith species.where n was the number of species sampled in the plant community, However, community-weighted mean has its inherent flaws, for instance by potentially mistakenly exacerbating the role of dominant species and by masking the other important information of trait distributions within the community . TherefoAs such, the variance signifies the amount of scale or dispersion of the trait value distribution in a community. Skewness signifies the level of left or right tailed asymmetry of the distribution of trait values, and highly absolute skewness means dominant traits locate in the extreme of the trait–abundance distribution. Such outcomes typically result from asymmetrical competition and/or rapid environmental change such as disturbance. Kurtosis signifies the relative extremes throughout the trait distribution, where higher values result from a community having species of high abundance with similar trait values  and lower values results from a community with species of even abundance but differential trait values . Indeed, mean and skewness of traits within communities reflect the patterns of trait dominance, and highly absolute skewness reflected high asymmetry of the trait distribution and is often associated with hierarchical competition. Variance and kurtosis of traits within communities could reflect two components of functional diversity: dispersion and evenness. Skewness and Kurtosis are mathematically related and their relationship is described as:a full mathematical demonstration of the Skewness- Kurtosis relationship, and its implications and use in various scientific fields were shown in Supplementary Note 1 of 2 +  1) was calculated as:Thus, a particular value of skewness of a specific leaf trait within communities must correspond to a lowest kurtosis. Here, the distance (D) between observed kurtosis and the lowest kurtosis  and mean annual temperature (MAT) were extracted using latitude and longitude coordinates. The de Martonne aridity index  were determined. Each null model was performed 9999 times. Previous studies used standardized effect size (SES) to assess non-random patterns of trait distribution  and species across forest sites  as our species pools. We randomly shuffled trait values using these species pools and null communities were created accordingly , then reribution , calculap < 0.05.Data analyses and visualization were performed using R software . The level of significance was established at s) versus palisade tissue thickness (PT), stomatal area fraction (f) versus spongy tissue thickness (ST); some trait-trait relationships became stronger, such as nitrogen content (N) versus specific leaf area (SLA), stomatal density (d) versus s. Lastly, the SLA-PT relationship was completely contrasting between the species and community levels.We observed significant relationships between certain leaf traits and when scaling these traits up to the community level, some trait-trait relationships were slightly different from those at the species level . From spPrincipal component analysis showed that leaf economic traits and hydraulic traits were decoupled at the species level but coupled at the community level . Compared) and stomatal area fraction (f) were closely related with AI. δ of palisade tissue (PT) and spongy tissue (ST) were less influenced by climate, but the relationships between δ values of PT/ST and AI were observed.δ values were significantly influenced by mean annual temperature (MAT), mean annual precipitation (MAP) and de Martonne aridity index (AI) . SpecifiAfter including climate variables as covariates, the moments  of leaf economic and hydraulic traits accounted for 24.59% and 33.46% of the variation in GPP , howeverMulti-dimensional traits—leaf economic, hydraulic and anatomical traits— were used to explore the principles of community assembly from tropical to cold-temperate forests. We found that adaptation mechanisms of plant communities and plant species might be different, evidenced by the decoupling of economic and hydraulic traits at the species level but coupling at the community level. When resources are limited, related leaf traits tended to be relatively even within communities, and trait-based community assembly always optimized their productivity. The insights provided by leaf functional traits in this study help us to better reveal the principles of community assembly in natural forests, and systematic investigation of plant traits  at a large scale is required for a comprehensive understanding of trait-based community assembly.We found a species level trade-off between specific leaf area (SLA) and the palisade tissue thickness (PT) and the spongy tissue thickness (ST) such that more resource acquisitive species had both lower PT and ST. Yet, we also confirmed coordination between SLA and the ratio of PT to ST, suggesting that more resource acquisitive species actually require more PT relative to ST, as this would be consistent with greater resource acquisition . While tWe found decoupling of leaf economic and hydraulic traits at the species level across 394 species from tropical to cold temperate forests, as has been demonstrated across 85 woody species in tropical-subtropical forests . A lack Trait-trait relationships represent coordinated ecological strategies and trade-offs of plants, due to the different strategies that could facilitate co-existence . Yet, sud) and stomatal area fraction (f) at the regional scale. Consistent with these findings, the ratio of palisade to spongy thickness was also distributed more evenly at sites with lower water availability, and highlights coordination between traits that scale to optimize resource-use efficiency  had more even trait distributions in plant communities with lower resource availability  . Furtherficiency . OverallIndeed, the distribution of leaf economic traits was more even under lower temperature and precipitation, while the distribution of hydraulic traits was more even only under lower water availability. This indicates that assembly of leaf economic and hydraulic traits in terms of functional evenness would differ depending on the temperature and water availability of a community, which permits communities greater flexibility to adapt to multifarious environments. We boldly speculated that under severe drought stress and suitable temperature, plant communities assembly with species with hydraulic traits more evenly distributed, given their mechanistic link with water use and to maximize resource use efficiency. By contrast, under low temperature and suitable water availability, plant communities assemble with species with economic traits more evenly distributed within the community. Moreover, the independent assembly of multiple trait dimensions within communities improves their adaptability.Establishing the linkages between plant functional traits and ecosystem functioning is a fundamental goal for ecologists. Studies have found that community-aggregated leaf economic traits , stomataCertain potential limitations of our study should be explicitly stated. Although leaf samples were only collected from 4 individual for each species, the species composition was almost completely different among nine typical forests, and interspecific variation of traits was much greater than the intraspecific variation . TherefoThe datasets generated for this study are available on request to the corresponding author.NH conceived the ideas. CL, YL, and JZ collected the data and led the writing of the manuscript. AB revised the manuscript. All authors contributed critically to the drafts and gave the final approval for publication.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


The paracrine effect, mediated by chemical signals that induce a physiological response on neighboring cells in the same tissue, is an important regenerative mechanism for stem cell-based therapy. Exosomes are cell-secreted nanovesicles (50–120 nm) of endosomal origin, and have been demonstrated to be a major contributor to the observed stem cell-mediated paracrine effect in the cardiac repair process. Following cardiac injury, exosomes deriving from exogenous stem cells have been shown to regulate cell apoptosis, proliferation, angiogenesis, and fibrosis in the infarcted heart. Exosomes also play a crucial role in the intercellular communication between donor and recipient cells. Human induced pluripotent stem cells (hiPSCs) are promising cell sources for autologous cell therapy in regenerative medicine. Here, we review recent advances in the field of progenitor-cell derived, exosome-based cardiac repair, with special emphasis on exosomes derived from hiPSCs. Cardiovascular disease caused by coronary obstruction accounts for up to 80% of all cardiovascular-related deaths . Cell-baWhile the primary goal of stem cell-based therapy is to generate new cardiac muscle, recent data from both clinical and preclinical studies have indicated that transplanted stem cells may exert their functional beneficial effects largely through their secretome, by which the paracrine activity of the transplanted cells is mediated in part through their secreted vesicles . SignifiIn this review, we summarize the current advances on the utilizing exosomes to treat ischemic heart disease and conclude with a discussion of current challenges and future prospects in this field.Extracellular vesicles (EVs) include exosomes (diameter range: 30–150 nm), microvesicles (diameter range: 50–1000 nm), and apoptosomes (diameter range: 50–5000 nm) . ExosomeExosomes equip a unique and powerful carrier for cells to deliver a variety of bioactive components and promote intercellular communication. Recently, exosomes from many stem cells, including mesenchymal stem cells (MSCs) , embryonin vivo cardiac protective effect of the exosomes released by iPSCs and their derivatives is summarized in Preclinical studies have shown that exosomes can be used as an effective therapeutic strategy for a variety of diseases as they regulate a broad range of cellular behaviors and promote intercellular communications. Secreted exosomes may be collected from the cell culture medium via well-established protocols . Pilot sin vitro and in aortic rings ex vivo study reported that exosomes from ALIX-overexpressing and ALIX-knockout hiPSCs provide stronger and weaker therapeutic benefits respectively, against cisplatin and oxidative damage in epithelial, epidermal, and endothelial cells (Transplanted iPSCs produce paracrine factors that enhance survival of native cells in the ischemic heart, however, the mechanisms remain largely unknown. It has been reported that exosomes, a cell-free component secreted from iPSCs, contain some specific miRNAs and cytokines that can provide robust cardiac protection and promotion of myocardial regeneration . Anotheral cells . Furtheral cells . A recenal cells .in vitro angiogenesis in several facets of tube formation, accompanying with increased expression of growth factors such as PDGFA, VEGF2A, and FGF2 in endothelial cells (in vitro (Angiogenesis is the formation of new blood vessels that helps to establish and support the normal structure and function of the cardiac tissues. Angiogenesis is defined as the migration, development and differentiation of endothelial cells to form new blood vessels . Exosomeal cells . Investial cells . Anotheral cells . It is dal cells , and proin vitro , via thein vitro .in vitro in a dose-dependent manner (Recent studies have demonstrated the beneficial effects of exosomes in enhancing the cell cycle activity in animal models of MI. For instance, exosomes secreted by CDCs were found to promote the proliferation of cardiomyocyte in mouse MI hearts . Similart manner  while iMt manner . Ye et at manner , indicatTeratoma is a benign tumor formed by cells from all three germ layers. Although iPSCs and their derivatives have been demonstrated to be effective for myocardial repair, the teratogenic risk of these cells remains a concern and limits the routine clinical uses of these cells . SeveralAlthough the beneficial components in the exosomes secreted from iPSCs are not fully identified yet, studies have shown that iPSC culture medium have the capability to improve alveolar epithelial wound-healing and reduce lung fibrosis in a lung epithelial wound healing model . Furtherin vitro but were also associated with the accelerated heart failure progression in patients (It is noteworthy to mention that in some cases, depending on cell- type as well as genotypic and functional status of the cells, specific components in the exosomes may not be beneficial but rather, harmful to the cardiovascular system . For exapatients . Exosomepatients . Yi et apatients . Applicapatients .Three different ways had been used to deliver exosomes to the ischemic heart tissue which include intravenous, intramyocardial and intracoronary injections . Exosomein vivo biodistribution need to be carefully investigated (Although detailed mechanisms on exosome-based myocardial repair have not been fully understood, here we would like to summarize the potential beneficial effects of such therapy from current studies discussed in this review . Collectstigated . Third, stigated . ExosomeCF, JZ, and WZ wrote the manuscript. EZ, JJ, and JY made the revision.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


In this introduction, we first summarize the Fourth International Workshop on Semantics-Powered Data Mining and Analytics (SEPDA 2019) held on October 26, 2019 in conjunction with the 18th International Semantic Web Conference (ISWC 2019) in Auckland, New Zealand, and then briefly introduce seven research articles included in this supplement issue, covering the topics on Knowledge Graph, Ontology-Powered Analytics, and Deep Learning. In the era of big data, the volume, the variety, as well as the velocity of data being generated have posed major challenges for people to leverage multiple data sets for decision making . OntologThe International Workshop on Semantics-Powered Data Mining and Analytics (SEPDA) has been established as an important venue for experts to discuss semantic-based methods and applications in health data analytics –8. To coIn this editorial, we summarize the papers included in this supplement. We categorize them into three main themes: Knowledge Graph, Ontology-Powered Analytics, and Deep Learning.The majority of biomedical knowledge is still locked in text format such as those from textbook and scientific literature, while downstream applications such as those that provide clinical decision support still heavily rely on structured discrete data. Systems that curate knowledge graphs and knowledge bases from biomedical literature are rational intermediate steps. The paper from Rossanez et al.  introducDeep learning, which can classify nodes in the knowledge graph with good predictive performance, suffers from poor interpretability. In the healthcare domain, interpretability of AI models is critical for clinical decision making. Vandewiele et al.  presenteThe needs to integrate diverse data sources across different domains  and levels  are growing so that a comprehensive examination of all potential risk factors is possible. The number of these multi-level integrative data analysis (mIDA) studies is increasing; nevertheless, the data integration processes in these mIDA studies are inconsistently performed and poorly documented. Zhang et al.  developeIn , Zhang eAmith and colleagues utilized their dialogue ontology called the Patient Health Information Dialogue Ontology (PHIDO)  to contrDeep learning has transformed medicine in the past few years . PredictCancer survivors often experience emotional stress, post-traumatic stress disorder (PTSD), and other mental health issues. As such, they are at a high risk of self-destruction and harming others . Early dIn this supplement of selected articles from the Fourth International Workshop on Semantics-Powered Data Mining and Analytics (SEPDA 2019), seven papers were accepted after a rigorous peer review process. These papers demonstrated the power of the semantic methods in various applications, many of which are addressing critical challenges in healthcare such as predicting treatment effect, identifying cancer survivors living with PTSD, and mining relationships among disorders, genes, and drugs from biomedical databases. We hope these papers will have sustainable impacts not only on biomedical and health informatics but also other related fields. We also hope more researchers will be motivated by these exciting results and join our effort to improve population health and advance biomedical research with semantics-powered data analytics over disparate datasets.


Photodynamic therapy (PDT) using oxygen, light, and photosensitizers has been receiving great attention, because it has potential for making up for the weakness of the existing therapies such as surgery, radiation therapy, and chemotherapy. It has been mainly used to treat cancer, and clinical tests for second-generation photosensitizers with improved physicochemical properties, pharmacokinetic profiles, or singlet oxygen quantum yield have been conducted. Progress is also being made in cancer theranostics by using fluorescent signals generated by photosensitizers. In order to obtain the effective cytotoxic effects on the target cells and prevent off-target side effects, photosensitizers need to be localized to the target tissue. The use of nanocarriers combined with photosensitizers can enhance accumulation of photosensitizers in the tumor site, owing to preferential extravasation of nanoparticles into the tumor vasculature by the enhanced permeability and retention effect. Self-assembly of amphiphilic polymers provide good loading efficiency and sustained release of hydrophobic photosensitizers. In addition, prodrug nanomedicines for PDT can be activated by stimuli in the tumor site. In this review, we introduce current limitations and recent progress in nanomedicine for PDT and discuss the expected future direction of research. PDT h–0.04 μs .The singlet oxygen with high reactivity can diffuse across the cell membrane and induce intracellular signaling, resulting in organelle damage and cell death .In order to obtain the effective cytotoxic effects on tumor cells (larger than 10 μm), photosensitizers administered in vivo need to be localized to the target tissue. In the current era of nanotechnology, scientific studies on the use of nanomaterials in PDT are increasing for the treatment of a wide range of diseases, especially cancer. Encapsulation of photosensitizer molecules into the nanocarrier targeting neoplastic endothelial cells can be selectively delivered to the tumor endothelium by the enhanced permeability and retention (EPR) effect . GeneratPharmacokinetic profiles of NIR photosensitizers together with the prognosis of diseases have also been studied by using NIR imaging . As goldHuman clinical studies on PDT for the treatment of early-stage bladder, skin, lung, esophagus, and stomach cancers showed promising therapeutic responses ,17,18,19Therefore, delivery to the specific target site and therapeutic efficacy must be investigated for the clinical use of nanomedicine for PDT. Although several challenges remain to expand the therapeutic application of PDT in the clinic, the advanced nanoplatforms potentially offer the best hope for PDT. In this review, we summarized therapeutic benefits of PDT and current limitations in their development or clinical use. We also discussed recent progress in nanomedicine for PDT as well as the expected future research direction.After photosensitizers combined with nanocarriers are intravenously injected into cancer patients or tumor-bearing mice, they can accumulate in the tumor tissue. They produce ROS only when excited by light of a specific wavelength and exhibit cytotoxic effects on tumor cells. As other normal tissues that have not been exposed to light irradiation are preserved, PDT has the following advantages and disadvantages compared to the existing standard cancer treatment such as surgery or chemotherapy.While chemotherapeutic drugs exhibit side effects not only on cancer cells but also on normal cells, photosensitizers combined with nanocarriers selectively accumulate in the tumor site and show cytotoxicity only in the area exposed to light irradiation. PDT can be performed instead of surgery in inoperable patients; light irradiation of the surgical site in patients who underwent tumor removal surgery can decrease the risk of cancer recurrence . CombinaHowever, contrary to systemic chemotherapy, local treatment using an optical fiber in PDT is hard to kill the tumor cells present outside the focal area or alter the therapeutic outcomes in patients with advanced-stage cancer . Under lAmong photosensitizer classes such as porphyrins, chlorophylls, and dyes, most photosensitizers approved for clinical use are derivatives of the porphyrin moiety . PorphyrIn order to be excited in the deeper tissue, the second-generation photosensitizers have been developed to show higher molar extinction coefficient in the near-infrared region than the first-generation photosensitizers . 5-AminoThe ratio between type I and type II reactions of photosensitizers in cancer depends on the concentration of oxygen and substrates in the tumor microenvironment (TME) . When exEffective cytotoxic effects can be obtained by localization of photosensitizers in the intracellular organelles such as mitochondria, nucleus, and lysosomes because of reactivity and short half-life of the ROS generated by light irradiation . In orde®), albumin-bound paclitaxel (Abraxane®), and PEGylated proteins are used in the clinical setting [Rapid progress in the field of nanotechnology facilitates control of physicochemical properties such as the diameter, shape, and surface functional group of nanomaterials. It has enabled development of nanomedicines that respond to stimuli including light irradiation and the expansion of PDT strategies in conjunction with nanomedicine . The use setting . In phas setting . It suggPreferential accumulation of cancer therapeutics in the tumor might be achieved by using stimuli-responsive nanoparticles with targeting ligands . DistribTo date, numerous nanocarriers such as polymers, micelles, liposomes, dendrimers, and inorganic nanoparticles have been studied for increasing therapeutic efficacy of photosensitizers. It is important to efficiently deliver photosensitizers and the generated singlet oxygen to the target site in the optimum therapeutic range. Pharmacokinetic or pharmacodynamic profiles of nanocarriers should also be checked for clinical use. Multifunctional nanoparticles are also currently being investigated for theranostic purpose or photodynamic/chemo dual therapy. Recent advances in preclinical developments using nanomedicine for PDT are categorized in + T cells.Natural polysaccharides such as hyaluronic acid (HA), heparin, chitin, chitosan, and fucoidan have been reported as potential photosensitizer carriers owing to their biocompatibility and biodegradability ,70,71. H2 catalyzing the decomposition of hydrogen peroxide to form oxygen. The nanocarrier can enhance accumulation of verteporfin in the tumor site through both P-selectin targeting and the EPR effect. The dendrimer–fucoidan nanocomplex could specifically target P-selectin-overexpressed breast cancer and tumor-associated vasculature [2 and improved the therapeutic efficacy of PDT for antimetastatic effects. Recent multifunctional nanoplatforms exhibit such characteristics as cancer targeting, improved pharmacokinetics/pharmacodynamics, and high photodynamic efficacy.Newly developed biocompatible nanocarriers not only encapsulate PDT agents, but also provide additional targeting effects for enhancing anticancer activities. Fucoidan exhibits binding affinity to P-selectin and the targeting effect on P-selectin-positive cancer cells ,75. Chunculature . It alsoIn order to overcome drawbacks of chemotherapy, nanocarriers for the combination of chemotherapy and PDT have also been developed. Ce6 was loaded into peroxidase mimic metal–organic nanoparticles and coated with HA . The nanAttachment of polyethylene glycol to the nanocarrier can provide hydrophilicity, decrease the clearance by the reticuloendothelial system, and extend circulation time. Polyethylene glycol (PEG) conjugated with hydrophobic stearamine carrying doxorubicin and pheophorbide A (PhA) accumulated in the tumor site, and the release of drugs from the nanocarrier with a ROS-sensitive linker was triggered by ROS within cancer cells . The outAs self-assembled polymeric micelles or liposomes have amphiphilic structures in an aqueous solution, hydrophobic photosensitizers can be loaded into the hydrophobic core space. Biocompatible phospholipids or polymers approved by the FDA used in self-assembly of organic nanomedicine are dissociated with cargo photosensitizers after being endocytosed into the target cells and offer no severe toxicity by themselves. Yoon et al. reported that Ce6, a hydrophobic photosensitizer, was loaded into amphiphilic HA nanoparticles grafted with hydrophobic 5β-cholanic acid groups, PEG, and Black Hole Quencher 3 . It showPhotosensitizers conjugated to polymers could also be self-assembled. Ce6 conjugated to mPEG-grafted HA formed self-assembled nanoparticles, in which camptothecin was encapsulated for photodynamic/chemo dual therapy . When anInorganic materials which are size-adjustable and large in surface area also show potential as self-assembled nanoparticles for PDT. The structure of the self-assembled porphyrin core–shell nanocomposite surrounded by a silica shell was constructed by the surfactant micelle and the silicate sol–gel process . Kineticl-lysine [Meanwhile, peptides or proteins are also promising candidates for modulating self-assembly of phototherapeutic nanoparticles; they exhibit structural or functional diversity and high biocompatibility or biodegradability ,83. Selfl-lysine . It undeIn addition, self-assembled nanomaterials are occasionally formed in different sizes, which facilitating deep penetration of photosensitizers or chemo drugs into the tumor. A dye–chemo drug conjugate was reported to enhance the photodynamic efficacy in its molecular self-assembly . The sizIn order to boost the ROS generation efficiency of photosensitizers with aggregation-induced emission (AIE), biocompatible polymers with stimuli-responsive bonds could be self-assembled into nanomicelles in water . RecentlIn recent years, efforts have been made to develop photosensitizers in which the singlet oxygen generation efficiency is suppressed in normal cells and increased only in the target tissue. Use of the nanomedicine that activates singlet oxygen generation only in the tumor site is expected to kill cancer cells while suppressing skin photosensitivity reactions. Stimuli-responsive prodrug nanomedicines have been developed for PDT.A prodrug conjugate between photosensitizer molecules and anticancer drug molecules with the caspase 3-cleavable peptide linker, Asp–Glu–Val–Asp (DEVD), was designed for targeted cancer therapy . Under mPEG was also used in prodrug nanomedicine formulations. Kim et al. reported ROS-sensitive prodrug nanoparticles for the combination of chemotherapy and PDT . Self-asChemo drugs can be dimerized by the stimuli-responsive chemical linkage for controlled drug release from prodrug nanoparticles. Paclitaxel encapsulated in the PEGylated peptide copolymer combined with a photosensitizer was reported to be activatable by light irradiation as light-boosted nanomedicines . The proOverall, the combination of a prodrug and a PDT agent is promising to achieve maximized therapeutic efficacy with lower toxicity for the successful clinical application of PDT. Prodrug nanomedicines can compensate for the limited efficacy of the ROS induced by light irradiation and PDT agents with low toxicity.Owing to minimally invasive characteristics, PDT is expected to be more widely applied by replacing surgery or chemotherapy for primary cancer lesions . It may The combination of chemotherapy with PDT has thrived as an efficient clinically available strategy to enhance the anticancer therapeutic efficacy and minimize the systemic toxicity of chemotherapy by reducing dose. Besides combination with chemotherapy, combination of PDT with immunotherapy is also being investigated. PDT-mediated destruction of local tumors causes infiltration of leukocytes and stimulates the immune system . As PDT Lack of water solubility or target specificity of photosensitizers can be supplemented by smart nano-enabled delivery systems. Controlled release nanocarriers and targeted photosensitizers are also being continuously developed. Nanomedicines that integrate characteristics of nanocarriers, self-assembled nanoparticles, and stimuli-responsive prodrugs are also emerging. Hydrophobic photosensitizers, for example, conjugated to hydrophilic carbohydrate derivatives through a ROS-responsive linker can be self-assembled into nanoparticles. When nanocarriers reach the tumor site, photosensitizers are be released from the nanoparticles by the ROS-responsive bond cleavage .As the molecular imaging technology advances and is applied to the clinics, the diagnosis and treatment of cancer at the early stage become more important. There has been a lot of research on theranostic nanomedicines for PDT . We may


Osteoporosis, the most common chronic metabolic bone disease, is characterized by low bone mass and increased bone fragility. Nowadays more than 200 million individuals are suffering from osteoporosis and still the number of affected people is dramatically increasing due to an aging population and longer life, representing a major public health problem. Current osteoporosis treatments are mainly designed to decrease bone resorption, presenting serious adverse effects that limit their safety for long-term use. Numerous studies with mesenchymal stem cells (MSCs) have helped to increase the knowledge regarding the mechanisms that underlie the progression of osteoporosis. Emerging clinical and molecular evidence suggests that inflammation exerts a significant influence on bone turnover, thereby on osteoporosis. In this regard, MSCs have proven to possess broad immunoregulatory capabilities, modulating both adaptive and innate immunity. Here, we will discuss the role that MSCs play in the etiopathology of osteoporosis and their potential use for the treatment of this disease. Osteoporosis, a skeletal disorder characterized by low bone mass and increased bone fragility, has no clinical manifestations until a fracture occurs. Osteoporosis is normally diagnosed in elderly patients, being increasingly recognized as a major public health concern . In 2013Bone is an organ in constant remodeling, finely orchestrated by two principal cell types: osteoclasts that degrade the bone matrix (bone resorption) and osteoblasts which synthesize a new bone matrix (bone formation). In osteoporosis, there is an imbalance between bone resorption and bone formation  mainly dThe diagnosis of osteoporosis is performed by image analysis  but nowadays, there is increasing interest in the use of bone remodeling biochemical markers for clinical applications in bone metabolic disorders. These bone turnover markers (BTM) are substances released into the circulation during the bone formation and/or resorption process, which reflect the metabolic activity of the tissue at a specific time and, therefore, their potential in the evaluation of bone metabolic disorders. The ideal bone remodeling marker should meet the following characteristics: non-invasive determination, ease of sample collection, be an specific product of bone metabolism, show correlation with reference techniques in the bone remodeling analysis such as bone histomorphometry, bone biopsy after double labeled with tetracycline, isotopic studies with labeled calcium and/or dual x-ray absorptiometry and respond to the specific treatment of diseases that affect bone metabolism .The identification and analysis of these markers is vital for the monitoring of osteoporosis as well as for other bone metabolic diseases, since the use of bone turnover markers allows following the progression of the disease and in addition the therapeutic response of the patient. Moreover, these markers have the capacity to predict the risk of fracture and therefore can be useful in the adoption of certain therapeutic decisions. Thus, several prospective studies examining the relationship between BTMs and subsequent fractures showed that one or more markers of bone turnover (formation or resorption) were significantly associated with fracture risk ,10,11. FA summary of the main bone turnover markers that exist, their peculiarities and their potential in osteoporosis management are detailed below.COL1A1 gene; and one pro-α2 chain, encoded by COL1A2. During bone resorption process, collagen is degraded into different fragments. C- and N-terminal telopeptides of type I collagen  are both fragments from the telopeptide region, a non-triple-helical portion near the ends of mature collagen molecule. Telopeptides are cleaved during osteoclastic resorption of bone and, are released into the blood stream at a rate which is proportional to bone resorption activity [Type I collagen is the most abundant protein component of bone, representing 90% of the organic extracellular matrix . Type I activity .Two types of proteinases have been described to take part in this process; the cysteine proteinases, which act at acidic pH and matrix metalloproteinases (MMP) that act at neutral pH. Thus, depending on the acting proteinase, one telopeptide molecule or another is released. CTX and NTX are generated from the activity of the cysteine proteinase cathepsin K, while the MMP or trypsin digestion of bone, leads to the release of cross-linked telopeptide of type I collagen (ICTP) . ActuallNTX can also be measured in serum or urine, although it is preferentially measured in urine; since urine NTX is more sensitive than serum NTX in detecting changes induced by antiresorptive therapies . To avoiPyridinoline (PYD) and deoxypyridinoline (DPD) are covalent pyridinium cross-links that bridge several collagen peptides and mechanically stabilize the collagen molecule . They arPYD is found in numerous tissues such as cartilage, bone, ligaments and vessels, while DPD is only detected in bone and dentin. In any case, the turnover of the bone is much higher than in the aforementioned tissues, so it is considered that the PYD and DPD of both, serum and urine, are produced mostly in the bone tissue. Moreover, since PYD and DPD levels are not altered by food intake, pyridinium crosslinks are viewed as good markers of bone resorption. Both free and conjugated forms of PYD and DPD have been shown to be stable in urine samples kept at room temperature for several weeks. If storage occurs at −20 °C they can last for years, the repeated freeze-thaw cycles of urine samples have no effect on their concentrations .Pyridinium cross-links can be detected and quantified by automated high-performance liquid chromatography (HPLC) , direct Hydroxyproline (OHP), an amino acid formed from the post-translational hydroxylation of proline, constitutes 12–14% of the total amino acid content of mature collagen . During Although urinary OHP is considered a bone resorption marker it should be taken cautiously since significant amounts of OHP in the urine proceed from newly synthesized procollagen during bone formation process . FurtherHydroxylysine is produced during the synthesis of collagen due to the post-translational modifications suffered by collagen. Subsequently, hydroxylysine can undergo additional modifications like glycosylation giving rise to two different forms; glucosyl-galactosyl-hydroxylysine (GGHL) and galactosyl-hydroxylysine (GHL). The glycosilation of the hydroxylysine is different depending of the tissue; GHL is specific for bone, while GGHL is the major form in skin . AlthougBoth of them are released into the circulation during collagen degradation and can be measured in the urine by HPLC after derivatization with a fluorescence compound . Later, The glycosylated forms of hydroxylysine are not metabolized before excretion in urine, as the case with hydroxyproline, nor are they affected by dietary intake. It has been estimated that urinary hydroxylysine glycosides represent the 50–100% of collagen breakdown, a much higher percentage than the estimated for OHP . TherefoThis enzyme belongs to the ubiquitous family of the acid phosphatases. There are five isoforms which are expressed in different cell types. All acid phosphatases are inhibited by L (+)-tartrate, except form 5, so the latter it was called tartrate resistant acid phosphatase (TRAP or TRACP). There are two TRACP subforms—type 5a, which contains sialic acid and type 5b, which does not, the latter being characteristic of osteoclasts . In factTRACP5b stability goes as follow: serum samples can be kept for 2 days at room temperature and for 3 days at 4 °C. However, for longer storage, freshly collected samples should be stored in aliquots at −20 °C for a maximum of one month or at −70 °C to remain stable for years .Bone sialoprotein, an important extracellular glycoprotein of mineralized tissues, represents the 5–10% of the non-collagenous matrix of bone. Although its theoreticalmolecular weight (MW) is 33 kDa, due to different post-translational modifications  it has an apparent MW of 60–80 kDa . BSP is Serum BSP can be measured by different immunoassays . SeveralCathepsin K is a protein of 329 amino acids form by a long N-terminal signal sequence of 15 amino acids, a 99 amino acid long propeptide and a 215 amino acid long catalytic unit . This pr−/− mice showed a marked increase in bone formation, increased cortical and trabecular thickness, seeming their bones mechanically more stable than those of the wild type mice [OC, also known as bone γ-carboxyglutamic acid-containing protein (BGLAP), is a non-collagen protein of 5.8 kDa. Although non-collagen proteins represent only 10% of the organic extracellular matrix, their roles in the regulation of bone turnover and mineralization are essential ,68. OC iype mice .OC is often used as a marker for late bone formation . It is sSerum OC presents a high biological and circadian variability, which might negatively affect the reproducibility of repeated measures. Either RIA, ELISA or a chemiluminescence immunoassay may be used to detect OC in serum ,76.Alkaline phosphatases (ALPs) are plasma membrane-bound glycoproteins. Human ALPs can be classified in four tissue-specific isoforms; placental alkaline phosphatase (PLALP or Regan isozyme), intestinal alkaline phosphatase (IALP), tissue nonspecific alkaline phosphatase (TNAP) and germ cell ALP (GCALP or NAGAO isozyme) . The tisIn order to differentiate between the two main circulating ALP isoforms, several techniques have been developed; namely, heat denaturation, electrophoresis, precipitation, selective inhibition and immunoassays . NonetheN-terminal and C-terminal propeptide of type I procollagen , are released from posttranslational modifications that type I procollagen molecule suffers during collagen assembly into fibrils . Both moPINP has 70 kDa and is rich in proline and hydroxyproline, which are essential for the triple helical structure stability. PINP is eliminated from the circulation by liver endothelial cells through their scavenger receptors . PINP prThe other molecule—PICP—consists of 115 kDa and it is produced in the same way that PINP during collagen synthesis in bone formation processes. PICP is stabilized by disulphide bonds and is cleared by liver endothelial cells via the mannose receptor which can be regulated by growth and thyroid hormones . PICP prPINP, on the other hand, presents a longer stability in serum besides being no affected by food intake and circadian rhythm. All of that, point this molecule as a remarkable biomarker. In fact, PINP has been recommended as the bone formation marker by the International Osteoporosis Foundation (IOF) and the International Federation of Clinical Chemistry (IFCC) for clinical research studies in osteoporosis . LikewisA healthy and active lifestyle is vital for the proper maintenance of all body tissues, including bone. Several studies have highlighted the importance of physical exercise to improve the quality of life of patients with osteoporosis ,93,94. RDiet also plays a fundamental role in bone health. Calcium supplementation has been shown to be able to decrease the rate of bone mineral density loss in women, although it does not seem to be enough to prevent fractures . The comBone resorption is highly determined by hormone levels, such us estrogens. As mentioned above, unopposed estrogen can increase the risk of breast and uterine cancers, deep vein thrombosis and stroke . TherefoAmong anti-resorptive drugs, the most used are bisphosphonates. Bisphosphonates are pyrophosphate analogues that bind to hard bone through their affinity for hydroxyapatite . They arDenosumab is a monoclonal antibody that binds with high affinity to receptor activator of nuclear factor kappa-Β ligand (RANKL), preventing the binding between RANKL and receptor activator of nuclear factor kappa-Β (RANK) and thus inhibiting the differentiation and activity of the osteoclasts . Unlike Although anti-resorptive osteoporosis medications reduce fractures, they have rare and serious adverse effects that may limit their safety for medium and long-term use, so new safe therapies capable of restoring skeletal structure and integrity are needed. In fact, current pharmacologic attempts for osteoporosis aim to prevent fractures through stimulation of bone formation. These agents target anabolic pathways to stimulate the osteoblastic activity, increasing the bone volume without inhibiting its resorption.The first approved agent to accomplish this was teriparatide. Teriparatide is a recombinant human parathyroid hormone (PTH), known to be the only available therapeutic agent that increases the formation of new bone tissue . PTH regRomosozumab, is another monoclonal antibody recently approved by the U.S. Food and Drug Administration (FDA) for the treatment of osteoporosis in postmenopausal women. The registered trade name of Romosozumab is Evenity. It is the first humanized anti-sclerostin monoclonal antibody that has been shown to increase bone formation with dual effect: on one hand, it increases bone formation and, on the other, although to a lesser extent, it reduces bone resorption (or bone loss) which translates into a decrease in the risk of fracture . HoweverSclerostin, expressed by osteocytes and articular chondrocytes, is the product of SOST gene. It is an endogenous inhibitor of the Wingless-type mouse mammary virus integration site (Wnt) signaling pathway. Wnt signaling has been described as a positive regulator of bone formation and regeneration  and thusIn summary, currently used osteoporosis therapies are not fully effective in all patients and present considerable side effects that seriously compromise their long-term use. Thus, the development of new therapeutic strategies for osteoporosis is craved in an increasingly aging world population with a longer life expectancy.As mentioned before, current attempts for developing safe new therapies are focused on anabolic therapeutic strategies, able to increase the activity of new bone forming cells (osteoblasts) and/or their progenitor.The osteoblasts progenitors, named as mesenchymal stem cells (MSCs) are spindle shaped cells with multipotent differentiation capacity in vitro. The International Society for Cellular Therapy (ISCT) has proposed minimum criteria to define MSCs. These cells (i) should exhibit ex vivo plastic adherence under normal conditions (ii) possess specific immunophenotype, such as the expression of CD73,CD90,CD105 and lack of CD14, CD34, CD45 and human leukocyte antigen-DR (HLA-DR) (iii) have the ability to differentiate into osteogenic, adipogenic and chondrogenic lineages in vitro .The study of MSCs and the pathways involved in adipogenesis, osteogenesis and chondrogenesis , have coIn healthy individuals, the rate of MSCs in bone marrow is very low (about 0.01 %–0.001 %) , being eMSCs fate determination is regulated by specific transcription factors ,133 and In addition, hMSCs from patients with osteoporosis and age-matched controls have been shown to exhibit different transcriptomes. Osteoporotic MSCs show an enhanced mRNA expression of genes involved in osteoclastogenesis  and genes coding for inhibitors of Wnt and bone morphogenetic protein (BMP) signaling, indicating intrinsic deficiencies in self-renewal and differentiation potential of osteoporotic stem cells .Given the diminished proliferation and differentiation ability of MSCs from osteoporotic patients, it is quite reasonable to contemplate the benefits of providing healthy MSCs to the patients to boost the bone anabolic pathway. Numerous efforts have been attempted in the field of cellular therapy based on MSCs applied to osteoporosis. In the beginnings, the cell therapy potential was focus on MSCs´ ability to target a damaged site and subsequently, to differentiate into osteoblasts in order to repair the degenerated tissue. However, the poor engraftment demonstrated by transplanted cells in humans  generateHowever, a recent murine study  has demoThe MSCs used to treat osteoporosis could have different origins: Bone-Marrow derived MSCs (BM-MSCs), adipose-tissue derived MSCs (AD-MSC) or umbilical cord derived MSCs (UC-MSCs). Although all of them have shown therapeutic effects for osteoporosis in preclinical studies, there are still some challenges on their clinical application, such as the limited long-term survival and the uncertainty of MSCs´ fate after transplantation depending on the source of MSCs ,143.Several studies in animal models intended to prove the potential of transplanted BM-MSCs to treat osteoporosis, both from allogenic and autologous sources.Different osteoporotic murine models have been used to demonstrate the therapeutic capacity of MSCs. Ichioka and collaborators  used an Ovariectomy (OVX)-induced rat model has also been used to challenge the potential of MSCs to treat osteoporosis. Allogenic BM-MSCs isolated from healthy rats were injected into the femurs of osteoporotic rats. The femurs of treated rats showed trabecular bone percentage almost similar to the femurs from control healthy rats. As expected, osteoporotic BM-MSCs showed less differentiation capabilities as compared to those isolated from healthy rats .Glucocorticoid-induced osteoporosis mouse model has also been applied to study the effect of the systemic injection of allogeneic BM-MSCs. The encouraging outcomes comprised inhibition of the decrease of bone mass and strength as well as stimulation of osteoblastogenesis, with consequent sustained bone formation .−/−, to demonstrate that systemic administration of allogeneic bone marrow MSCs, noticeably improved bone formation and maintained the microarchitectural capability.Finally, Kiernan, Hu, Grynpas, Davies, & Stanford (2016)  made useIn addition, further non-murine animal models have been used to study the beneficial effect of BM-MSCs injection to treat osteoporosis. Autologous BM-MSCs had been transplanted in an OVX-induced rabbit model of osteoporosis, displaying more bone apposition, stronger stiffness of bone, raised trabecular thickness and developed microstructures with freshly formed osteoids . SimilarPhase I clinical trial is currently ongoing, where autologous fucosylated (a type of glycosylation) BM-MSCs are infused into osteoporotic patients. However, there is some uncertainty regarding the use of autologous BM-MSCs for osteoporosis treatment in elderly patients, due to the age-related decline in the overall BM-MSC number ,149  and the bone morphogenetic protein receptor type 1B (BMPR-IB) signal pathway .BM- and AD-MSCs are effective sources of MSCs but their therapeutic potential can be affected by the donor’s lifestyle and age. Thus, bone regenerative medicine has focused its efforts on finding new sources of MSCs in perinatal tissues, such us umbilical cord . These cBone formation by umbilical cord-derived MSCs (UC-MSCs) was demonstrated in vivo by Diao and collaborators who loaded human UC-MSCs into scaffolds that were transplanted subcutaneously into BALB/c nude mice, observing efficiently bone formation by UC-MSCs . An et aSo far, there are no clinical trials with UC-MSCs cells applied to osteoporotic patients.Emerging clinical and molecular evidence suggests that inflammation exerts significant influence on bone turnover, thereby in osteoporosis. Estrogen deficiency is the main cause of osteoporosis in post-menopausal women. This condition results in increased production of inflammatory cytokines, describing osteoporosis as an inflammatory disease ,162,163.Bone fractures repair is mediated not only by the bone but also with the aid of the immune system, being crucial in the process . In factThe first phase of bone healing is characterized by an acute inflammatory response; the release of interleukin-1 (IL-1), interleukin-6 (IL-6) and TNF-α recruits B and T lymphocytes. T lymphocytes have a pro-osteogenic role, by releasing interleukin-17F (IL-17F) . This cyMSCs have been shown to possess immunoregulatory abilities , being cMSCs have been broadly demonstrated to be able to modulate the differentiation, function and balance of T cells subpopulations  and promote the development of an anti-inflammatory immune response . Indeed,MSCs have been demonstrated to exert an immunosuppressive function on dendritic cells (DCs), which are considered the bridge between innate and adaptive immune system. They can inhibit DCs differentiation and maturation in a reversible manner ,185. MSCAs for the innate immune system, some studies have shown that MSCs are capable of inhibiting NK cell proliferation, cytokine release and cytotoxicity, via prostaglandin E2 and indoleamine dioxygenase ,189. TheLastly, increasing evidences have shown that the regulation of macrophages by MSCs is essential for the inflammatory response and tissue lesions repair. It has been reported that MSCs can interact with monocytes and macrophages to reprogram them . When MSIn summary, these results demonstrate the regulatory role of MSCs in the innate and adaptive immunity, due to their ability to down-regulate the intensity of an immune response. Since inflammation seems to significantly contribute to the etiopathogenesis of osteoporosis ; it is pOsteoporosis is a skeletal disorder increasingly recognized as a major public health problem. Current osteoporosis treatments are no safe for long-term use, so the development of new therapeutic strategies is needed. MSCs are increasingly considered as promising tools as a new therapeutic strategy to treat osteoporosis, mainly due to its ability to secrete factors that are directly or indirectly involved in bone repair; as well as, its ability to graft into tissues and differentiate into functional osteoblasts. Emerging evidence suggests that inflammation exerts significant influence on bone turnover, thereby in osteoporosis. In fact, MSCs also have the capacity to interact with different immune cells, so the immunomodulatory capacity of MSCs could be an interesting approach to treat osteoporosis.


Hyperuricemia is a risk factor for gout. It has been well observed that a large proportion of individuals with hyperuricemia have never had a gout flare(s), while some patients with gout can have a normuricemia. This raises a puzzle of the real role of serum uric acid (SUA) in the occurrence of gout flares. As the molecule of uric acid has its dual effects in vivo with antioxidant properties as well as being an inflammatory promoter, it has been placed in a delicate position in balancing metabolisms. Gout seems to be a multifactorial metabolic disease and its pathogenesis should not rely solely on hyperuricemia or monosodium urate (MSU) crystals. This critical review aims to unfold the mechanisms of the SUA role participating in gout development. It also discusses some key elements which are prerequisites for the formation of gout in association with the current therapeutic regime. The compilation should be helpful in precisely fighting for a cure of gout clinically and pharmaceutically. Hyperuricemia has been defined as serum uric acid (SUA) >6.0 mg/dL in women; >7.0 mg/dL in men; >5.5 mg/dL in children and adolescents , and is It has been well observed and puzzled for a long time that not all hyperuricemia patients suffer from gout , only upTreatment of hyperuricemia in individuals without gout has been contentious partially due to the interrelationship between hyperuricemia and gout being not fully understood. Exploring such a mechanism, therefore, would be helpful in guiding the establishment of proper therapeutic regimes for both. This critical review aims to gather recently published literature for the elucidation of the interrelationship between hyperuricemia and gout in their pathogenesis, clinical evidence of the inflammation effects, MSU crystal formation, and therapeutic regimes, and attempts to explain why hyperuricemia does not necessarily induce gout.Uric acid (UA) is the end catabolic product of exogenous and endogenous purine nucleotide metabolism in humans. It exists in blood serum/plasma, cells, and tissues with steady-state conditions of its production and disposal. Its production can be found in almost all tissues, while its major disposal is via kidneys. SUA concentrations can be reflected by the intake from diet, in vivo purine metabolism, renal secretion, and intestinal degeneration . In vivoBeyond its role in protection, over-saturated SUA together with sodium could deposit in joints, soft tissues, bones, skin, etc., as MSU crystals to form tophi and trigger gout flares with episodes of severe pain. Gout is a common and complex form of arthritis with a sudden attack(s) of pain, swelling, redness, and tenderness in the affected location(s). Tophaceous gout has been defined as classic periarticular subcutaneous tophi, disseminated intradermal tophi, an ulcerative form, and gouty panniculitis  and commκB signaling pathway [+ (activating receptors of simulation of cytotoxicity) NK cells [The major symptom of a gout flare is the MSU crystal-induced sterile inflammation with UA controversially being an intrinsic inhibitor of MSU crystal-induced tissue inflammation  and a di pathway , or dire pathway . Intra-a pathway . Althoug pathway , and the pathway  through  pathway  involve  pathway  and ofte pathway . MSU dep pathway . MoreoveNK cells . It coulNK cells ,50 resulNK cells  or alterNK cells , respectNK cells ). TherefNK cells . Indeed,vice versa. Reducing blood lipid levels with a lipid-lowering agent(s) could concurrently reduce SUA level [It has been found that only about half of those with SUA concentrations of ≥10 mg/dL developed clinically evident gout during a 15-year period . DespiteUA level , suggestUA level .In spite of hyperuricemia, it has been established that pre-biological fiber damage could be a prerequisite for MSU crystal deposition . In the An increase in UA concentration that exceeds the normal range might not be exclusively linked to gout flares  as many Gout can be self-resolvable with symptoms disappearing within days or weeks when hyperuricemia might still be sustained. Therefore, the symptoms might not be paralleled with a reduction in SUA level. The immunoreaction generated anti-UA antibody could also prevent or reduce inflammation conditions to release gout flare symptoms . Under hThe increased SUA after fasting for a long term may not induce any gout flares , plausibThe traditional treatment for gout flares has been well established for the improvement of quality of life , althougTraditional Chinese medicine treats gout with efficacy and the fundamental strategy seems to target specifically restorations of metabolisms and immunity as well as inhibition of inflammation and peripheral nerve sensation . This maHyperuricemia is a main, but not the only risk factor for gout flares. Recent publications suggest gout formation would be well beyond hyperuricemia in MSU crystal deposition with pathogenic mechanisms involving an activation of various inflammation pathways with UA and MSU, the critical conditions of secondary SUA deposition, and the degree of intact surrounding tissue(s). The differentiation may explain the existence of asymptomatic hyperuricemia with the UA nature of the anti-oxidative stress, gout symptom self-resolution, and some passive increase of SUA irrelevant to gout. Hyperuricemia could only be accompanied by the aforementioned factor(s) to instigate a gout flare . The patKey taking home messages: 1. The role of serum uric acid (SUA) should, above and beyond, be an exclusive indicator of a gout flare. 2. Hyperuricemia would not be the only risk factor of a gout flare due to many irrelevant elements between them. 3. Monosodium urate (MSU) deposition requires a pathology environment with damaged bio-fiber integrity other than hyperuricemia.