Solanum mauritianum). Recruitment of native species was further enhanced by local structure in herbicide-treated areas, being consistently greater under live trees and dead non-native shrubs (herbicide-treated) than in open areas, and intermediate under bird perches. Native seedling recruitment comprised 28 species across 0.25 ha sampled but was dominated by two rainforest pioneers . These early results are consistent with the expected increase in woody vegetation recruitment in response to release from competitive and dispersive barriers to rainforest regeneration. The findings highlight the need for a pragmatic consideration of the ecological roles of woody weeds and the potential roles of “new forests” more broadly in accelerating succession of humid tropical forest across large areas of retired agricultural land.Combating the legacy of deforestation on tropical biodiversity requires the conversion to forest of large areas of established pasture, where barriers to native plant regeneration include competition with pasture grasses and poor propagule supply (seed availability). In addition, initial woody plants that colonise pasture are often invasive, non-native species whose ecological roles and management in the context of forest regeneration are contested. In a restoration experiment at two 0.64 ha sites we quantified the response of native woody vegetation recruitment to (1) release from competition with introduced pasture grasses, and (2) local facilitation of frugivore-assisted seed dispersal provided by scattered woody plants and artificial bird perches. Herbicide pasture grass suppression during 20 months caused a significant but modest increase in density of native woody seedlings, together with abundant co-recruitment of the prominent non-native pioneer wild tobacco ( Approximately half of the world's tropical biomes have been subjected to some form of clearing  herbicide-induced release from competition with introduced pasture grasses; and (2) local facilitation provided by elements of habitat structure, specifically scattered trees, shrubs, and artificial bird perches. We test whether rainforest seedling recruitment increases when competitive and dispersive barriers to regeneration are reduced. We also describe the extent and pattern of co-recruitment by non-native invasive woody plants, and discuss the findings in the context of current understanding of old field restoration in the tropics, with a particular emphasis on the contentious role of woody weeds in efforts to reinstate forest over large areas.Urochloa decumbens) and pasture legumes, with guinea grass (Megathyrsus maximus) and setaria (Setaria sphacelata var. anceps) also widely established, together with a wide variety of other planted and invasive species.An experimental restoration project  was established in November 2011 in areas adjoining the Mt Hypipamee/Upper Barron section of the Wet Tropics World Heritage Area, on the Atherton Tableland, north eastern Australia. The native vegetation is complex notophyll to mesophyll vine forest Tracey, . LandscaSo far, three kickstart pasture conversion sites have been established, each on red basaltic soil in an area of retired pasture which slopes steeply northwards to an east-flowing gully bordering a large area of conserved rainforest. In this paper we restrict most analyses to two sites from which the longest data time series is available  with one side abutting the rainforest edge: (1) the “Works plot” within which all experimental management works took place; and (2) the “Control plot,” a similar delineated area of retired pasture which remained untreated Figures , S2. ManGrasses, herbs and other low-growing pasture-associated plants were suppressed with repeated herbicide applications, at a frequency which depended on weather conditions and observed grass or herb regrowth, as judged during regular site inspections . To reduce external influences, a 5.0 m wide buffer around the perimeter of the Works plot was also treated with herbicide. Herbicides were either glyphosate  or the grass-selective Fusilade (fluazifop-p butyl) and Verdict . The initial herbicide treatment in each Works plot aimed to achieve comprehensive glyphosate coverage of all ground-level plants, with no attempts to locate or protect small native forest seedlings, very few of which were apparent. Subsequent treatments were either spatially selective sprays with glyphosate, to spare any recruiting native rainforest seedlings, or more generalized sprays of grass-selective herbicide. Concentrations and application methods were those typically used by experienced restoration practitioners during establishment and maintenance of rainforest replanting projects in the region. Decisions about the type and delivery of herbicide  were made independently and progressively for each site, depending on local topography, how the vegetation had recently developed, and the type of herbicide involved. These decisions were also guided by the underlying goal of longer term cost efficiency within a management context. Overall, during 20 months there were 7–10 herbicide treatments (varying in different parts of the plot) at CloudlandE, and seven at CloudlandW; and during the 9 months at Ringtail there were 6–7 sprays. Some treatments involved broadscale grass suppression, while others were more spatially localized, and targeted specific clumps of herbs, grasses, shrubs or scrambling vines. The nature of these treatments requires close tailoring of actions to suit each local combination of climate and ground-cover species.Alphitonia petriei , cut at the base, with branches pruned back to a standard form . At the base of each sapling there was a water tray  which filled mainly from ambient rainfall with occasional hand supplementation, together with two logs (each about 1.0 m long and 20–25 cm diameter). Nine perches were installed in each Works plot in a regular grid of 20 m spacing, with three rows of three perches at each of 20, 40, and 60 m away from, and parallel to, the forest edge.Each bird attracting structure (henceforth a “perch”) was constructed from an existing multi-branched Alphitonia petriei, Acacia celsa, Rhodamnia sessiliflora, and Xanthophyllum octandrum. Care was taken during herbicide applications to avoid these trees. Dead clumps were almost all either lantana (Lantana camara) or wild tobacco (Solanum mauritianum), and were killed by stem treatment with Starane (fluroxypyr). A few small localized patches of very low growing native shrub  or other small woody non-native plants were also killed with herbicide treatment during initial plot establishment.The pre-existing trees and shrubs in each plot were mapped if they were >2.0 m tall. These consisted of two types: (1) small native regrowth trees (henceforth termed “live trees”), and (2) non-native woody shrubs, all of which were treated with herbicide as part of the initial Works plot establishment (henceforth termed “dead clumps”). Live trees were mostly Here we present data from seedling recruitment surveys conducted 20 months after the Works plots were established at the two Cloudland sites , and 9 months after the establishment of the Ringtail Works plot. Seedling recruitment was measured in two types of systematic search area: strips and circles. Strips were positioned regularly throughout both the Works and Control plots, and circles were placed around perches, live trees or dead clumps. In both types of search, all recruits of woody-stemmed trees or shrubs were counted and identified to species level if they: (1) were seedlings ; (2) were >10 cm in height; and (3) belonged to any species (native or non-native) which develops a woody stem that can typically exceed 2.5 cm diameter as individuals grow. The height of each stem was also measured, up to a maximum of 2.0 m (after which diameter was recorded).Strips were transects 20 m by 2 m, positioned parallel to the forest edge. An arrangement of four strips laid end to end spanned the full width of the plot, and this was repeated at eight distances from the forest edge , giving a total of 32 search strips in each plot Figure . Circles2 to account for the difference in sampling area between search types . To examine the effect of grass suppression, mean recruit densities were compared between Works and Control plots, with strips as replicates but excluding all strips that intersected with live trees or dead shrubs, to remove the potential confounding effect of structure on recruitment  were standardized to a density unit of stems per 100 mSignificance tests of treatment effects were conducted using data from the two Cloudland sites, for which 20 month data were available. Tests were performed using generalized linear models based on a Poisson error structure and log link function, implemented using the glm function in the base “stats” library of R  and circle (N = 40) surveys at the two Cloudland sites at 20 months (after excluding strips that intersected with pre-existing trees and shrubs). Of these, 345 were seedlings of 28 native rainforest plant species, the most common being the early successional trees Homalanthus novoguineensis , Polyscias murrayi , Alphitonia petriei , Solanum viridifolium , and Wikstroemia indica   whereas A. petriei dominated CloudlandE (18% of 92). Five non-native species were recorded. However, S. mauritianum (Solanaceae) was consistently by far the most common, comprising 99% of 1046 seedlings . Recruitment attributable to non-native species was also greater following grass suppression and at the CloudlandW site where mean abundance of stems reached 57.5 seedlings per 100 m2 .Across both Cloudland Works plots, the mean height of native seedlings recorded in the analyzed strips and circles after 20 months was 61 cm ; and for circles across both types of plot Spearman's r = 0.92 at CloudlandE and 0.66 at CloudlandW .For native recruits, the area-specific species richness values were strongly and positively correlated with their measured densities: for strips in open areas of Control and Works plots Spearman's Almost no new seedlings emerged from the retired pasture Control plots over this study's 20 month period, supporting the idea that recruitment barriers are present. Repeated applications of herbicide to suppress the pasture grasses and herbs had a modest but discernable impact to enhance native seedling recruitment. This finding is broadly consistent with other regional and international studies where various interventions have been employed to alleviate ground conditions and promote the short term recovery of woody vegetation on degraded tropical land, although many of these did not differentiate between native and non-native species  which constituted the vast bulk of woody stems in open areas, and formed an extensive closed canopy 3–4 m tall over substantial parts of one experimental site (CloudlandW) within 20 months  supports the view that this species has ecological properties which facilitate forest succession. It is therefore possible that the new S. mauritianum stands which emerged after pasture suppression will provide positive feedback to enhance future seedling recruitment.This ability to colonise pasture, form a shady canopy, and quickly produce crops of fruit which are attractive to many seed dispersing frugivores  and can impair the early shoot and root growth of some native tropical rainforest trees , and so have the potential to overtop it. While species' growth rates vary, some H. novoguineensis individuals had grown as tall as, or taller than, the S. mauritianum within the 20 months of this study. Longer-term monitoring is needed to determine the capacity and time required for self-organized recruitment and growth of rainforest trees to shade out stands of S. mauritianum, and how well this development trajectory corresponds with time preferences for restoration outcomes.Our findings likewise lead to a conclusion that evaluation of non-native pioneers' transience at sites is critical to making informed management decisions. Like many of its congeners, This study illustrates the role of shifting patterns of competitive inhibition, and its interactions with ecological facilitation, during old field succession in retired agricultural land. Initially pasture grasses outcompete rainforest seedlings, but any forest trees that do establish, as well as invasive woody shrubs, can then outcompete the grass. Subsequently there are also bidirectional potential competitive processes between native and invasive woody species. Understanding of the nature of interactions between different plant functional groups, in terms of both life-form and species origin, is fundamental to these processes, and has important practical applications in the imperative to achieve rapid reforestation of large areas of degraded agricultural land in the tropics. Strategic interventions can accelerate forest recovery, if appropriately selected and timed on the basis of this knowledge. Our findings reaffirm the importance of combined intervention approaches that are designed to overcome multiple ecological barriers, in some cases simultaneously and in others sequentially. Our findings also highlight the importance of retaining or actively reinstating “islands” of woody vegetation as regeneration foci in restoration (Zahawi et al., S. mauritianum and whether further interventions such as selective clearing or planting will be required to hasten this process. Our incidental field observations also suggest that the potential importance of herbivory by wildlife in mediating the recruitment of recruited seedlings in retired tropical pastures (see also Holl and Quiros-Nietzen, A crucial gap in knowledge is the timeframe required for larger stature native tree species recruited into the seedling community to overtop the dominant non-native woody pasture invaders such as Empirical tests of the effectiveness of strategies other than active tree planting to simulate regeneration of tropical forest on degraded land have increased considerably over the last two decades (Shoo and Catterall, 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.


HOTAIR is an lncRNA that plays a role as an oncogenic molecule in different cancer cells, such as breast, gastric, colorectal, and cervical cancer cells. Therefore, HOTAIR expression level is a potential biomarker for diagnostic and therapeutic purposes in several cancers. This RNA takes part in epigenetic regulation of genes and plays an important role in different cellular pathways by interacting with Polycomb Repressive Complex 2 (PRC2). In this review, we describe the molecular function and regulation of HOTAIR and its role in different types of cancers.Long non-coding RNAs (lncRNAs) refer to a group of RNAs that are usually more than 200 nucleotides and are not involved in protein generation. Instead, lncRNAs are involved in different regulatory processes, such as regulation of gene expression. Different lncRNAs exist throughout the genome. LncRNAs are also known for their roles in different human diseases such as cancer.  We also present the molecular function and regulation of this lncRNA in different types of cancer.In this review, we describe the oncogenic roles of HOTAIR lncRNA was introduced by Rinn et al.HoxC gene, which is specifically situated between HoxC11 and HoxC12 on chromosome 12q13.13. Computational and Northern blot analysis revealed that HOTAIR does not show any stem loops suggestive of being a pre-miRNA. These analysis also suggested that HOTAIR is preferentially expressed in posterior and distal sites of the human body. In an experiment on 10 mammalian genomes and 3 non-mammalian vertebrates, He et al.HOTAIR and its two conserved domains. They reported a poor sequence conservation and, by contrast, noticeably conserved structures for HOTAIR. They also reported that HOTAIR has evolved faster compared with adjacent HoxC genes.HOTAIR is a trans-acting lncRNA and has different target loci such as HOXDHOTAIR interacts with Polycomb Repressive Complex 2 (PRC2) and is necessary for PRC2 occupancy and histone H3 lysine-27 trimethylation of different genes in different chromosomes. PRC2 is a histone methyltransferase that implements epigenetic silencing during different processes including cancer developmentHOTAIR localizes and targets PRC2 genome wideet al.HOTAIR functions as a molecular scaffold and interacts not only with PRC2 but also with LSD1 complex to regulate gene expression. LSD1 involves in demethylation of histone H3 at lysine 4,HOTAIR, and HOTAIR coordinates their functions for chromatin modificationHOTAIR affects the expression of multiple genes involved in various cellular functionsHOTAIR is an oncogenic factor and can be used as a prognostic biomarker in different cancer typesHOTAIR lncRNA plays a key role in the initiation and progression of different types of cancer such as cervical cancer and nasopharyngeal carcinoma,HOTAIR also plays an important role in promoting malignancyHOTAIR expression levels and lymph node metastasis, Cai et al.HOTAIR expression level had a higher incidence compared with that in patients with low HOTAIR expression level. Moreover, Alves et al.HOTAIR in epithelial-to-mesenchymal transition (EMT) and also its role in arising and maintenance of cancer stem cells (CSCs). They revealed that HOTAIR plays an important role in the process of tumorigenicity by triggering EMT and acquiring stemness.HOTAIR is involved in several processes associated with carcinogenesis such as those affecting the mobility, proliferation, apoptosis, invasion, aggression, and metastasis of the cells  complex in the presence of microRNA-141 (miR-141). MiR-141, unlike HOTAIR, is a suppressor of tumorigenicity, invasiveness, and malignancy in several cancer types. MiR-141 first binds to HOTAIR to suppress it, and Ago2 complex comes into play and cleaves the HOTAIRThe function of HOTAIR expression in cancer cells. Receptor CD44, a positive regulator of OPN, affects the expression level of HOTAIR. By contrast, interferon regulatory factor 1 (IRF1) decreases HOTAIR expression level by binding to its promoter. In fact, OPN regulates IRF1 and affects its signaling pathway, thus activating HOTAIR expression by suppressing the function of IRF1A type of phosphoglycoprotein called osteopontin (OPN), which is an extracellular matrix protein, can transcriptionally activate and increase HOTAIR. c-Myc is an oncoprotein that plays a role in the development of several types of cancer through regulating several protein-coding and non-coding genes. c-Myc recognizes a putative E-box element in the upstream region of HOTAIR, which is approximately located at the 1,053 upstream within its promoter. c-Myc directly interacts with this E-box element and upregulates the expression of HOTAIR. In addition, knockdown of c-Myc can reduce both HOTAIR expression and its promoter activity, whereas upregulation of c-Myc gene increases HOTAIR expression and its promoter activityHOTAIR promoterThe protein c-Myc is another element that impacts the expression of HOTAIR in these cellsHOTAIR. Estrogen receptors (ERs) and ER coregulators, such as histone methylases mixed lineage leukemia (MLL) 1, MLL3, and CREB-binding protein/p300, induce the expression of HOTAIR by binding to its promoterResearchers working on human breast cancer cells have shown that diethylstilbestrol and bisphenol-A can upregulate the expression of HOTAIR expression and involves in EMT, which results in arising and maintenance of CSCsHOTAIR upregulation. Zhuang et al.HOTAIR in lung cancer cellsHOTAIR overexpression has been reported in non-small cell lung cancerTGF-β is another factor that induces et al.HOTAIR lncRNA in mouse can result in activation of hundreds of genes. Different downstream pathways and genes are attributed to the molecular roles of HOTAIR in human cells. HOTAIR can act through promoting the chromatin relocalization done by PRC2. This targeting of PRC2 in the genome leads into a distinct pattern of gene expression necessary for breast cancer progression,HOTAIR-binding motif and BRCA1-binding region in EZH2. This finding indicates that decreased expression of BRCA1 results in elevated recruitment of PRC2 by HOTAIR in breast cancer cell linesLi HOTAIR in the development and progression of esophageal squamous cell carcinoma (ESCC) has been revealedHOTAIR exerts its role through activating Wnt/β-catenin signaling pathway. The Wnt/β-catenin signaling pathway is an important pathway in the development of ESCC. HOTAIR recruits PRC2 directly to the promoter region of Wnt inhibitory factor 1 (WIF-1), leading to the reduction of WIF-1 expression and consequently the activation of Wnt/β-catenin signaling pathway,HOTAIR locus that affects the regulation of HOTAIR may influence ESCC riskThe key role of in vitro and in vivo assays on epithelial ovarian cancer (EOC) tissues, researchers showed that a significant association exists between HOTAIR expression level and metastatic stage of EOC. This association may be due to the regulation of certain matrix metalloproteinases (MMPs) and EMT-related genes by HOTAIR. HOTAIR expression is also associated with FIGO stage/metastasis of lymph nodes; thus, this factor could be a potential biomarker or therapeutic target in EOC patientsThrough a series of HOTAIR in gastric cancer cells leads to EMT process reversal and reduction of invasiveness mediated by the expression of MMP1 and MMP3miR-7 by HOTAIR can mediate EMT progression in breast cancer. This microRNA can inhibit the SETDB1 and STAT3 pathway in breast cellsInhibition of HOTAIR can function as competitive endogenous RNAs (ceRNAs) in gastric cells by recruiting the microRNAs targeting the HER-2. Thus, HOTAIR and HER-2 may have coexpression in gastric cancer tissuesHOTAIR, the finding indicative of the positive interaction between HOTAIR and HER2 is worth to research in other types of cancer cells.miRNA-130a binding sites were found in HOTAIR lncRNA. A negative correlation between HOTAIR and miRNA-130a has been demonstrated in gallbladder cancer tissues compared with nearby normal tissues. Thus, the oncogenic role of HOTAIR is not only by recruiting PRC2 but also partly through negative regulation of miRNA-130aHOTAIR overexpression is also related to hepatocellular carcinoma (HCC)-et al.HOTAIR leads to the increase of RNA binding motif 38 (RBM38) proteins, which play a role in the regulation of cell motility. They also showed that RBM38 expression levels were lower in HCC tissues compared with noncancerous tissues in the same patients. Therefore, HOTAIR increases the aggression and invasion of HCC cells by suppressing RBM38 expression.HOTAIR plays an oncogenic role partially via the downregulation of HOXA5MUC5AC and ASTN1et al.HOTAIR regulates the expression of multiple genes in cooperation with PRC2 and raises the levels of undifferentiated cancer cells in CRC patients.Some reports indicate that et al.HOTAIR expression level of Ta/T1 bladder cancer tissues and adjacent normal tissues, which were collected from 110 patients. They reported that 90 specimens had high HOTAIR expression levels, which were inversely correlated with WIF-1 expression. HOTAIR may also be involved in the development of colorectal cancer,In an experiment, Yan et al.HOTAIR expression level in renal carcinoma cells. They also reported that knockdown of HOTAIR by siRNA impacts the cell cycle in the G0/G1 phase and also decreases the cell proliferation and invasion in vitro. These effects resulted in the reduction of HOTAIR binding ability to EZH2 and consequently the reduction of H3K27me3 on HOTAIR target genes. Furthermore, they showed that inhibition of HOTAIR expression resulted in suppression of growth of xenograft tumors formed by renal carcinoma cells. In addition, they demonstrated that inhibition of HOTAIR expression and modulation of covalent histones activated transcriptional state of cell cycle-related gene.Wu et al.HOTAIR in melanoma cells and showed that HOTAIR is overexpressed in metastatic melanoma tissues. They showed that knockdown of HOTAIR by siRNAs resulted in the reduction of motility and invasion of human melanoma cell line A375. They also reported that HOTAIR is involved in promoting gelatinase activity in melanoma cells.Tang HOTAIR has several effects, such as increasing the proliferation and aggression of cancer cells in pancreatic cancer tissues. On the contrary, downregulation of HOTAIR has opposite effects, including inhibition of cell cycle progression, reducing proliferation, and increasing apoptosis. However, the results of gene array studies showed that some differences exist between HOTAIR-regulated genes in pancreatic cells and breast cancer cells. These studies suggest several interferon- and cell cycle-related genes as targets of HOTAIR in pancreatic cancer cellsHOTAIR may be associated with endometrial carcinoma,Different studies revealed that increasing the expression of HOTAIR in glioma and glioblastoma are still challenging, HOTAIR can be used as a prognostic biomarker in gliomaAlthough the exact roles of HOTAIR in the initiation and progression of various cancers. Understanding the biological roles of HOTAIR in different types of cancer helps us to determine the efficiency of this lncRNA as a diagnostic or predictive biomarker. However, HOTAIR has been suggested as a biomarker for most cancer types. Thus, conducting a meta-analysis of HOTAIR expression in all cancer types may help in the identification of the cancers that have the highest probability of HOTAIR overexpression. Hence, HOTAIR expression level can be used as a potential prognostic factor for various cancers. In addition, screening the HOTAIR overexpression can help us identify cancer progression and tumor stage. Expression analysis can be conducted by different quantitative techniques such as RT-PCR. These assays would be valuable when the RNA level can be differentially analyzed in samples of patients such as urine, blood, and mucus. However, clinical trials are needed in the future to find this RNA as a suitable biomarker or therapeutic target in cancer.Different studies provide some evidence for the crucial roles of HOTAIR can also be further considered as a therapeutic target to improve the sensitivity of therapy for different tumors. Moreover, the efficacy of these therapeutic approaches can be further expanded via identification of exact molecular pathways underlying the regulation of HOTAIR expression. Although some regulatory pathways of HOTAIR expression have been reported, thorough identification of those pathways requires more studies and experiments.


The cerebral cortex is essential for our higher cognitive functions and emotional reasoning. Arguably, this brain structure is the distinguishing feature of our species, and yet our remarkable cognitive capacity has seemingly come at a cost to the regenerative capacity of the human brain. Indeed, the capacity for regeneration and neurogenesis of the brains of vertebrates has declined over the course of evolution, from fish to rodents to primates. Nevertheless, recent evidence supporting the existence of neural stem cells (NSCs) in the adult human brain raises new questions about the biological significance of adult neurogenesis in relation to ageing and the possibility that such endogenous sources of NSCs might provide therapeutic options for the treatment of brain injury and disease. Here, we highlight recent insights and perspectives on NSCs within both the developing and adult cerebral cortex. Our review of NSCs during development focuses upon the diversity and therapeutic potential of these cells for use in cellular transplantation and in the modeling of neurodevelopmental disorders. Finally, we describe the cellular and molecular characteristics of NSCs within the adult brain and strategies to harness the therapeutic potential of these cell populations in the treatment of brain injury and disease.  Excitatory projection neurons are born from local NSCs residing within the dorsal telencephalon, and these neurons migrate radially to position themselves appropriately within the developing cortex and hippocampus , while the ventral telencephalon  gives rise to the basal ganglia (reviewed in ). NSCs fiewed in ). DifferA remarkable feature during cerebral corticogenesis is the synchronous development and complementary positioning of temporally derived interneurons from the ventral telencephalon and projection neurons from the dorsal telencephalon, such that functional neural circuits are established between excitatory projection neurons and their appropriate inhibitory interneuron counterparts –4. In alThe Diversity of NSCs within the Embryonic Cerebral Cortex. NSCs are defined by their capacity to self-renew, as well as be able to generate neurons, astrocytes, and oligodendrocytes. In contrast, not all neural progenitor cells (NPCs) exhibit self-renewal capacity. The diversity of NSCs and NPCs  is, in part, responsible for the diversity and relative population densities of neuronal subtypes within the cerebral cortex. Early in the formation of the cerebral cortex, the dorsal telencephalon comprises a uniform layer of neuroepithelial cells. The local NSCs of the germinal ventricular zone (VZ), which lines the vesicular lumen, initially undergo self-renewing, proliferative divisions. At approximately mid-gestation in rodents, a subset of NSCs transition to become lineage-restricted NPCs and accumulate as a secondary proliferative layer above the VZ, described as the subventricular zone (SVZ). A population of NSCs undergo neurogenic divisions to form an early, transient neuronal layer above the SVZ, known as the preplate (PP). As corticogenesis progresses, newborn neurons split the PP layer to form an outer marginal zone (MZ), an underlying cortical plate (CP), and a subplate (SP). The MZ comprises a small (1–3%) population of distinct progenitors [genitors  as well genitors  and whicgenitors ). Over tIn the last two decades, significant progress has been made to describe the cellular heterogeneity of embryonic NPCs and NSCs in the dorsal telencephalon . NotablyAPs are NSCs that remain in contact with the luminal wall and form adherens junctions with other Apical Progenitors. APs are also identified by the apical location of their mitoses, are able to translocate their nuclei along the vertical axis in a cell cycle dependent fashion (termed interkinetic nuclear migration (INM) , 51), anThe BPs, the second type of progenitor cell within the cortex, are identifiable by their detachment from adherens junction complexes within the VZ, their location within the SVZ, their expression of the transcription factor TBR2 , and their capacity to undergo basal rather than apical mitotic divisions , 55. BPsMore recently, a new type of cortical progenitor, SAPs, was recognised to be distinct from APs and BPs, owing to the abventricular location of their mitoses and their ventricular contact . These SWhile excitatory cortical projection neurons are generated from NSCs of the dorsal telencephalon, inhibitory cortical interneurons are largely generated from the germinal zones of the ventral telencephalon. In mice, the ventral telencephalon is organised into several prominent structures termed ganglionic eminences, each with distinct NSC and NPC populations that generate specific neuronal subtypes. For example, NPCs of the lateral ganglionic eminences (LGE) generate striatal projection neurons and interneurons destined for the olfactory bulb, while NPCs residing within the medial ganglionic eminences (MGE) generate cortical interneurons that invade the dorsal telencephalon, as well as local projection neurons of the globus pallidus. Also, the anterior entopeduncular area (AEP) is recognised as a source of interneurons that populate the dorsal cortex via tangential migration . NotablyWhile it is clear that the primary source of cortical interneurons in rodents appears to be the ventral telencephalon, the developmental origin of human cortical interneurons appears to involve both the ventral and dorsal cortex, with evidence supportive of a limited contribution by dorsal cortical progenitors. Letinic and colleagues presented the first evidence that prominent numbers of interneuron progenitors could be found within the dorsal cortex, as identified by their expression of Dlx1, Dlx2, and Mash1 . This fiInsights into the Molecular Regulation of NSCs within the Embryonic Cerebral Cortex. Over the course of embryonic cortical development, the timing of NSC proliferation and neurogenesis is guided by cell extrinsic and cell intrinsic factors. The cerebrospinal fluid (CSF) courses through the ventricular system of the neural tube to deliver numerous signalling factors that influence the proliferative potential of cortical NSCs [ Lim-homeodomain 2 (Lhx2), Forkhead Box G1 (FoxG1), Paired Box Domain 6 (Pax6), and Empty Spiracles Homologue-1 and Empty Spiracles Homologue-2 (Emx1 and Emx2) in a region-specific manner. Notably, Lhx2 is detected in the entire telencephalon except for the dorsal midline, while Foxg1, Pax6, and Emx1 are expressed in cells of the dorsal telencephalon, and Emx2 is expressed throughout the telencephalon [cal NSCs . As earlcal NSCs . Such excephalon . Lhx2 deficiency using lineage-specific cre-driver mice have revealed its role in NSC proliferation and neurogenesis. In studies of conditional (loxp) mice crossed with Nestin-cre to delete Lhx2 throughout the developing nervous system, Lhx2 was found to regulate progenitor proliferation and neurogenesis through β-catenin signalling [ Lhx2 in telencephalic progenitors using Emx1-cre mice led to the formation of olfactory cortex rather than lateral cortex in a critical developmental window (E10.5) in embryonic mouse development [ Pax6, as revealed by Shetty and coworkers, who demonstrated that loss of Lhx2 in mouse embryos from E11.5 onwards led to the loss of distinct neurocircuitry  which accompanied changes in the regional identity of the cortex and which appeared to phenocopy Pax6 deficiency [The expression patterns for these abovementioned transcription factors reflect their instructive roles for NSC proliferation and neurogenesis. For example, Lhx2 specifies cortical and hippocampal cell fates, and studies of knockout mice reveal that its absence results in the expansion of adjacent structures, including the midline structures known as the cortical hem and antihem , 70. Morgnalling . Deletioelopment . The actficiency . Foxg1 in the mouse results in repatterning of the cortical field to cortical hem and hippocampus, together with the concomitant loss of cortical plate neurons [ Foxg1 expression is critical for their migration from the IZ to the CP through a mechanism which, in part, involves modulation of Unc5D expression [ Foxg1, with its selective loss resulting in the commensurate disruption of this temporal sequence for the production of cortical glutamatergic neurons [In the case of Foxg1, its expression within the E9.5 embryo is observed as a high-rostrolateral-to-low-caudomedial gradient. Deletion of neurons . In newbpression . In addi neurons , 77. Hen versus ventral telencephalic identity [ In situ hybridisation studies reveal a regionalised pattern for Pax6 in the dorsal telencephalon, with high rostrolateral expression and low caudomedial expression. In contrast, Emx1 and Emx2 expression is detected in an opposing  gradient [ small eye that revealed that Pax6-deficiency led to ectopic expression of ventral telencephalic genes by dorsal telencephalic NSCs, including Mash1, Gsh2, and Dlx1/2 [ Emx1/2 result in a reduction in the size of the cortex [ Pax6/Emx2 double-mutant embryos reveal that both these genes are required in concert for establishing the identity of dorsal cortical NSCs, since their compound loss results in the lack of the dorsal telencephalon, and an expansion of ventral telencephalic domains across the entire cortex [In contrast to Lhx2 and Foxg1, studies of mouse corticogenesis reveal that Pax6 is critical for dorsalidentity –81. In sgradient . Pax6 wad Dlx1/2 –81. Mutae cortex , but stue cortex . Togethe Pax6 display a selective loss of cortical neurons destined for upper layers [In addition to the functions for Pax6 in cortical regionalisation, additional studies have underscored its importance in regulating the transition between APs and BPs within the embryonic cortex, as well as its role in driving neurogenesis. For example, Pax6 activates expression of the proneural basic helix-loop-helix (bHLH) transcription factor Neurog2 in APs to instruct their neuroprogenitor fate and to drive neuronal subtype specification in postmitotic neurons . Pax6 alr layers –90.Neurog2EGFPKI) mice indicate that Neurog2 is expressed in early postmitotic neurons which have exited S/G2/M-phases of the cell cycle [ Neurog1/Neurog2 double-mutant mice [ Ascl1 loss-of-function mutants there is depletion of NSCs of the ventral telencephalon and medial ganglionic eminence, as well as their neuronal progeny [ Neurog2, or both Neurog1 and 2, leads to ectopic expression of Ascl1 by dorsal telencephalic progenitors, as well as the subsequence ectopic expression of ventral telencephalic genes, including Dlx1, Dlx2, Dlx5, and the GABAergic neurotransmitter genes Gad1 and Gad2 [ Neurog2/Ascl1 double-mutant embryos [The role and interplay of intrinsic factors in cortical neuron specification and subtype identity is perhaps best exemplified in studies of Neurog2 and its related family members Neurog1 and Ascl1. Both Neurog2 and Neurog1 are specifically expressed by APs and, to a lesser extent, BPs . Furtherll cycle . On the ant mice , 92. In  progeny . Interes embryos . Thus, t embryos , 58, 94  Neurog2 and Ascl1 leads to a significant reduction in neuronal production coupled with premature initiation of gliogenesis within the embryonic cortex [ S100β and glial fibrillary acidic protein (Gfap) [ Rp58 leads to a disruption of NSCs and BPs [ Neurog2-like gene regulatory sequences, repressing candidate gene expression as well as antagonising the functions of Neurog2-type transcriptional activators [ Neurog2 [ Neurog2-target genes, such as Rnd2 [Studies of proneural bHLH transcription factors in the embryonic cortex can also provide insights into the timing of neurogenesis versus gliogenesis by NSCs. For example, loss of bothc cortex . The expc cortex . A propon (Gfap) . More re and BPs , prematu and BPs , and def and BPs , 99, 100 Neurog2  as well  nuclear factor one (NFI) family of transcriptional regulators  [ Nfia, Nfib, or Nfix led to an expansion of NSCs (marked by Pax6 expression), but without an accompanying increase in BPs (marked by Tbr2) [ Nfi deficiency resulted in a reduction in gliogenesis, marked by Gfap expression [ Gfap regulatory region (marked by dissociation of the DNA methyltransferase Dnmt1 from this locus), which was coincident with promoter occupancy by the activator Stat3 [ Ezh2 and Sox9 is directly suppressed by Nfib [ in vitro and that Ezh2 and Sox9 expression is elevated in Nfib and Nfix knockout mouse embryos. Interestingly, the expression of the two Notch-induced stem cell regulators, namely, the Hairy-Enhancer-of-Split (Hes) genes Hes1 and Hes5, is also elevated in Nfia and Nfib knockout mice, further suggesting a role for both NFIs in suppressing NSC self-renewal [ Gfap expression through an indirect mechanism. Taken together, these examples provide insight into the underlying mechanisms which regulate embryonic NSCs. Given the relatively recent discovery of the extensive cellular heterogeneity of NSCs in the developing cerebral cortex, as well as the potential differences between rodent and human NSCs [Insights into the regulation of neurogenesis versus gliogenesis by NSCs can also be gleaned from studies of thend Nfix) –104. Thend Nfix) ). Nfia, nd Nfix) , 107, anby Tbr2) –110. Curpression , 112. Toor Stat3 . While t by Nfib  and Nfix by Nfib  in vitroman NSCs   of the hippocampal dentate gyrus and the SVZ lining the lateral ventricles. In the SGZ, NSCs give rise to Intermediate Progenitors and then immature granule neurons, which integrate into existing hippocampal circuitry (reviewed by ). In theThe dogma concerning the developmental origin of SGZ and SVZ adult NSCs has been that NSCs within the SGZ arise from the dentate neuroepithelium during embryonic development and that NSCs within the SVZ represent a continuation of embryonic progenitors from the lateral wall that become specified during the early postnatal period. Recently however, both of these views have been challenged.The view that SGZ NSCs solely originate from the dentate neuroepithelium was promoted by a pioneer study of rat dentate gyrus development from Altman and Bayer . In thisTwo recent studies have also challenged the origin of Type B1 stem cells in the rodent SVZ. Because prior studies had shown that B1 cells are derived from NSCs from multiple regions of the germinal ventricular zone surrounding the lateral ventricles during development , 125 andTogether, these studies have shed a new light on the developmental origin of NSCs within the adult cerebral cortex. The most surprising and unifying element of these studies is that the NSCs within these niches are specified early during development, during mid-neurogenesis within the fetal brain. These findings emphasise the tight temporal regulation of adult NSC specification and suggest that the specification of these cells may not be solely due to stochastic processes during the early postnatal period. Indeed, the broad significance of these findings relates to enhancing our understanding of the developmental origin of adult NSCs in rodents and extending these investigations into primate brain development, which will be key to comprehending the basic biology of these cells in the human brain and so being able to harness their potential for use in regenerative medicine.Arguably just as important as studying the developmental origin of adult NSCs is to understand the niche factors and molecular signals that maintain these cellular populations throughout life. Excessive proliferation of adult NSCs (or loss of quiescence) leads to premature depletion and reduced neurogenesis in the long term , 127–129The spatially restricted nature of neurogenesis in the SGZ and SVZ of the adult brain suggests that there are important local cues that are released to maintain NSC populations. The structural organisation of the niche and the morphology of NSCs support this idea. For example, in the hippocampus, clusters of NSCs are located close to the tips of capillaries . LikewisInterestingly, the cellular source of some of the most important and canonical niche signals that regulate neurogenesis, such as Notch, Wnt, and Shh pathways, is largely unknown. Some of these signals may come from the vasculature or CSF, but they could also come from other cellular components within the niche. For example, coculture of NSCs with niche astrocytes promotes neurogenesis, but this process is not evident when NSCs are cultured with astrocytes from nonneurogenic regions , suggestThere are many molecular regulators of NSC in the adult brain. An exhaustive discussion of all the molecules and signalling pathways that regulate NSC within the adult brain is beyond the scope of this review. Rather, here we highlight major factors that play a role in this process, which are listed in In adult NSCs, similar to their embryonic counterparts, some of the most well-established signalling nodes are the Notch, Bmp, and Wnt pathways. The first of these two pathways, Notch and Bmp, promote NSC quiescence , 129, whOf increasing interest to the field is how epigenetic modifications modulate adult NSC behaviour. Chromatin modifications such as DNA methylation of proximal promoters affect the accessibility of chromatin and therefore transcription . For exa Dicer affected levels of the neuroblast marker doublecortin. Moreover, the RNA interference machinery comprising Dicer/Ago2 was enriched in the chromatin of differentiating versus undifferentiated neural progenitor cells. Similarly, the role of long noncoding RNAs (lncRNAs) has also recently implicated in adult neurogenesis. Of the few lncRNAs studied thus far, both negative regulators of neurogenesis, such as Six3os and Dlx1as [ Pnky [Looking forward, the study of noncoding RNAs will also be an important area in the adult neurogenesis field. Testament to this is a blunt experimental approach taken by Cernilogar and colleagues  where thd Dlx1as , and a ps [ Pnky , have beOverall, the many regulators of SGZ and SVZ NSCs are testament to the inherent complexity of the cell biology of these cell populations. The future challenge will be to continue to characterise the biological regulators of adult NSCs using existing reductionist approaches and, crucially, to then place these findings in their cellular context through systems biology. In doing so, we will then be well placed to identify signalling pathways and molecules that are therapeutic targets for stem cell-based therapies for degenerative conditions. Increasingly, these efforts will also be accelerated by single-cell sequencing technologies. These technologies provide unprecedented insight into the diversity of cell types in adult neurogenic niches. For example, recent studies employing this technology have revealed subpopulations of NSCs that become activated after ischemic brain injury  or expos in vivo has guided the attempts by some to generate these cells in vitro to treat epilepsies through cellular transplantation. Likewise, the dysfunction of adult NSCs is increasingly thought to underlie several major disorders including depression, anxiety, and neurodegenerative disease, although direct causal evidence is lacking. Accelerating endogenous neurogenesis in these contexts may therefore improve patient outcome  of mice could reduce the incidence and duration of seizures in a genetic model of epilepsy resulting from a mutation to the potassium channel gene Kv1.1 . NotablyIn addition to fetal cortical sources of cells for transplantation, a study by Gaspard and coworkers pioneered the culture of mouse embryonic stem cells in the presence of a chemical inhibitor of the morphogen Shh to generate cortical glutamatergic neurons in a temporally specified manner . A furthRecent technological innovations in cell culture and pluripotent stem cell biology have further converged on the capacity to study the molecular and cellular basis for developmental brain disorders using a three-dimensional culture system , 154. A While an understanding of fetal neurogenesis can guide our development of cell-based methods to model cortical neurogenesis and developmental brain disorders, a better understanding of the fetal NSC compartment will enable us to identify sources of repair cells which could be mobilized in times of injury or stress. Looking to vertebrates such as zebrafish, a recent excellent study by Barbosa and colleagues described the maintenance of MZ-like stem cells in the periphery of the forebrain from birth to adulthood, and these stem cells can be activated to restore lost brain tissue upon injury . Given t NeuroD4 [Knowledge of the molecular mechanisms that drive fetal NSC neurogenesis could also lead to the development of novel cellular substrates for cell transplantation therapy. Guided by insights into the neurogenic programming potential for proneural bHLH factors, Masserdotti and colleagues have recently reported that forced expression of Ascl1 or Neurog2 in postnatal astrocytes and mouse embryonic fibroblasts led to their reprogramming into neurons . However NeuroD4 . Such stHarnessing existing endogenous populations of adult NSCs could likewise have numerous therapeutic applications in disease and for improving brain function in healthy individuals . For exaIn support of the second claim of the neurogenic theory of depression, electroconvulsive therapy (ECT), which is a well-established tool for treating depression, increases hippocampal neurogenesis in adult rodents , 176. FuDespite these unresolved issues, designing drugs that selectively increase hippocampal neurogenesis stands out as a logical therapeutic strategy in the treatment of depression, particularly since there have been few new antidepressant drugs with novel modes of action in the last decade . ImportaAnother potential therapeutic intervention of NSCs is to apply them to ameliorate the age-related cognitive decline of the brain. Ageing is associated with a decline in neurogenesis (–201; pluAre these age-related changes in neurogenesis associated with compromised cognitive capacity? Studies report conflicting results. Aged rats that perform better in the Morris water maze test of spatial learning and memory have more proliferating cells and newborn neurons than age-matched controls , 214. OtSeveral mechanisms have been put forward to explain the age-related decline in neurogenesis. Ageing has been associated with changes in the hippocampal NSC niche vasculature . MoreoveIn this paper, we have highlighted the cellular and molecular diversity of NSCs in the fetal and adult cerebral cortex. This research is critical as a basis for our understanding of the dynamic properties of embryonic and adult NSCs and how we might be able to manipulate them at the cellular and molecular level. This work has been facilitated by rapid advances in molecular and cellular techniques, as well as sequencing modalities and lineage tracing paradigms. Indeed, this suite of basic research has served as a springboard to drive the therapeutic applications of NSCs towards the treatment of brain injury and disease. While many of these therapeutic approaches are in the early, preclinical stage, it is likely that the knowledge gleaned from the ongoing study of embryonic and adult NSCs will enable the continual refinement of cellular replacement techniques and the identification of therapeutic targets that will lead to real treatments for brain injury and disease in the clinic. Such achievements will realise the promise of NSC research, which has for a long time held the imagination and fuelled the hope for researchers, clinicians, patients, and the broader community.


Multiple sclerosis (MS) is an immune-mediated disorder of the central nervous system that results in destruction of the myelin sheath that surrounds axons and eventual neurodegeneration. Current treatments approved for the treatment of relapsing forms of MS target the aberrant immune response and successfully reduce the severity of attacks and frequency of relapses. Therapies are still needed that can repair damage particularly for the treatment of progressive forms of MS for which current therapies are relatively ineffective. Remyelination can restore neuronal function and prevent further neuronal loss and clinical disability. Recent advancements in our understanding of the molecular and cellular mechanisms regulating myelination, as well as the development of high-throughput screens to identify agents that enhance myelination, have lead to the identification of many potential remyelination therapies currently in preclinical and early clinical development. One problem that has plagued the development of treatments to promote remyelination is the difficulty in assessing remyelination in patients with current imaging techniques. Powerful new imaging technologies are making it easier to discern remyelination in patients, which is critical for the assessment of these new therapeutic strategies during clinical trials. This review will summarize what is currently known about remyelination failure in MS, strategies to overcome this failure, new therapeutic treatments in the pipeline for promoting remyelination in MS patients, and new imaging technologies for measuring remyelination in patients. However, despite the development of increasingly effective therapies, a cure for MS has not been found and MS patients continue to suffer from chronic progressive disability. Currently, approved treatments for MS work by reducing immune system activity or blocking entry of immune cells into the central nervous system (CNS). Although these treatments can reduce relapse rates and severity of attacks, they do not repair immune-mediated damage to the myelin sheaths surrounding axons. Chronic demyelination leads to degeneration of axons and eventually loss of neurons. Neuronal loss correlates highly with clinical disability, highlighting the need for treatments that promote neuronal survival in both relapsing and progressive forms of MS. Experimental models of MS  persist in the adult CNS. Unlike neurons, which fail to regenerate after CNS insult, adult OPCs are capable of proliferating and differentiating into mature oligodendrocytes that myelinate axons in response to injury or damage –5. DespiOne hypothesis for remyelination failure is that the number of adult OPCs available for remyelination is depleted over time , 2, 4, hNTR, TROY, and LINGO-1 (leucine-rich repeat- and Ig domain-containing Nogo receptor-interacting protein 1) to inhibit both axonal regeneration as well as oligodendrocyte differentiation and remyelination  3A and 3F have been shown to be upregulated in active demyelinating but not chronic lesions in MS patients . These mAs lesions develop, astrogliosis, a hallmark of MS pathology, occurs in and around lesions, resulting in both structural and biochemical changes. Astrocyte secretion of cytokines can influence lymphocyte infiltration , 40 whilDisruptions in the glial–neuronal network between astrocytes, oligodendrocytes, and neurons also lead to metabolic deficiencies across cell types that cause cellular dysfunction and death –56. As nSeveral non-disease-related factors such as age, sex, diet, and individual genetic background can also impact the efficiency of remyelination –61. For There are several potential strategies to enhance the remyelination capacity of endogenous OPCs, such as manipulating intrinsic signaling pathways within oligodendrocytes to override the inhibition of remyelination or altering the lesion environment to be more permissive of OPC differentiation and remyelination. Transplantation to increase OPC numbers is probably not necessary in MS given the large numbers of OPCs present in adult brain tissue. Likewise, if endogenous OPCs sense injury and enter lesions, but cannot differentiate there, then enhancing the overall proliferation/migration of OPCs is unlikely to dramatically alter their capacity to remyelinate axons. Therefore, after dampening inflammation, it is crucial to support the survival and differentiation of endogenous adult OPCs in order to stimulate remyelination within the altered microenvironment of MS lesions, while also prolonging survival of denuded axons so that they may be effectively remyelinated.An important approach to myelin preservation and repair is the pharmacological manipulation of intrinsic signaling pathways. Small molecules that can target specific components of the signaling pathways that underlie myelination will need to be developed and tested. Fortunately, much has been learned about the many signaling pathways that govern oligodendrocyte differentiation and myelination over the last three decades , to be more permissive to endogenous OPCs. As mentioned above, the addition of enzymes, such as chondroitinase and hyaluronidase, is not very practical in a multifocal demyelinating disease such as MS. Therefore, an alternative approach is to change cellular responses to hostile environments. One promising target is the Nogo-A co-receptor LINGO-1, which is expressed by both neurons and oligodendrocytes. LINGO-1 acts as a negative regulator of oligodendrocyte differentiation and myelination. LINGO-1 knockout mice have enhanced remyelination in several demyelination models, including EAE and toxin-induced demyelinated lesions , 130. FuPreclinical studies of a recombinant human IgM antibody (rHIgM22) indicate that it may protect oligodendrocytes and stimulate myelin repair , 124. rHOligodendrocytes have very high metabolic demands due to production of extensive amounts of lipid-rich myelin membrane. This makes oligodendrocytes particularly sensitive to disruptions in metabolic homeostasis. Hypoxia/ischemia, oxygen–glucose deprivation, viral infections, and high rates of protein synthesis in the endoplasmic reticulum (ER) can all lead to ER stress, which activates pancreatic ER kinase (PERK) phosphorylation of eukaryotic translation initiation factor 2α (eIF2α) and the integrated stress response (ISR) . The ISRGuanabenz is an α2 adrenergic receptor agonist that has been previously approved by the FDA for the treatment of hypertension . Guanabein vitro and in vivo without affecting oligodendrocyte survival or proliferation  and Ca(2+) and is over-expressed in acute MS lesions. Blockade of ASIC1 through amiloride, a potassium-sparing diuretic that is currently licensed for hypertension and congestive cardiac failure, showed neuroprotective and myeloprotective effects in experimental models of MS , 106. A Promising results have been achieved with laquinimod, a small molecule that in addition to its effects on lymphocytes can also reduce glial reactivity , 140. AlOne of the biggest difficulties in the development of remyelination therapies for MS is the demonstration of remyelination in living patients. Indirect measures, such as improvements in neurophysiological outcomes, such as electroencephalography, evoked potentials, optical coherence tomography, and transcranial magnetic stimulation may suggest, yet not confirm, remyelination –148. Funin vivo assessment of this dynamic process in both visible lesions and the putatively “normal appearing white matter (NAWM).” Candidate imaging sequences must be sensitive and specific for changes occurring in vivo, correlate with other indicators of remyelination, and crucially for quantitative MRI, must be reproducible across imaging platforms.Demyelinating lesions are readily detected by T2-weighted (T2W) and fluid attenuated inversion recovery (FLAIR) MRI –156. UnfDiffusion tensor imaging (DTI) tracks the Brownian motion of water molecules in tissue to provide quantitative data about tissue microstructure, and is particularly well-suited to highly ordered environments such as CNS white matter . For difin vivo: a “free” pool of protons that are generally unbound in an aqueous environment, and a “restricted” pool of protons that are bound to high molecular weight molecules such as lipids and proteins (Magnetization transfer (MT) imaging exploits the exchange of magnetization that occurs between two “pools” of protons proteins , 175. WhAlthough edema, inflammation, and axonal density do influence MTR, the high lipid content of myelin strongly affects the MTR , 176–178Brain tissue microstructure is complex and each tissue component displays different T2 relaxation characteristics. The differences in T2 relaxation correlate with water separated into three components: a long T2 component corresponding to CSF, an intermediate T2 component corresponding to intra/extracellular water, and a short T2 relaxation time component corresponding to water trapped with layers of myelin . Of mostEarly techniques for measuring MWF depended on 2D multi-spin echo acquisitions, which due to time considerations permitted only incomplete coverage of the brain. To improve brain coverage and further reduce MT effects, other sequences are now available, including 3D-GRASE and most recently mcDESPOT, which allow coverage of the entire brain within reasonable acquisition times , 194. Wh11C-PIB is currently used in the imaging of Alzheimer’s disease (11C-PIB uptake was less in enhancing lesions (Positron emission tomography (PET) uses radioisotopes that directly bind to different tissue substrates to enable molecular imaging. Direct binding of imaging biomarkers specific for myelin could potentially far exceed the specificity of the other modalities discussed above and allow investigators to detect changes specific for myelin content in the brain. One such biomarker is the thioflavine-T derivative 2-(4′-methylaminophenyl)-6-hydroxybenzothiazole (PIB).  disease , 201 but disease , 203. InRepair and remyelination in MS is possible, but remyelination often fails as a consequence of failure to recruit OPCs fully into the lesions, failure of OPCs to generate mature myelinating oligodendrocytes, and failure of oligodendrocytes to remyelinate axons. Several candidates to enhance remyelination are currently under investigation with a variety of mechanisms of action. One barrier to evaluating remyelination therapies in patients is the lack of methods to accurately detect myelination, demyelination, and remyelination with standard imaging technologies. Advancements in MRI technology allow better detection of myelin-specific changes but criteria that can be readily quantified using new imaging technologies will have to be established and validated to determine the success of remyelination in clinical trials.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.


Theoretical ecology predicts that heterogeneous habitats allow more species to co-exist in a given area. In the deep sea, biodiversity is positively linked with ecosystem functioning, suggesting that deep-seabed heterogeneity could influence ecosystem functions and the relationships between biodiversity and ecosystem functioning (BEF). To shed light on the BEF relationships in a heterogeneous deep seabed, we investigated variations in meiofaunal biodiversity, biomass and ecosystem efficiency within and among different seabed morphologies  in a narrow geo-morphologically articulated sector of the Adriatic Sea. We show that distinct seafloor morphologies are characterized by highly diverse nematode assemblages, whereas areas sharing similar seabed morphologies host similar nematode assemblages. BEF relationships are consistently positive across the entire region, but different seabed morphologies are characterised by different slope coefficients of the relationship. Our results suggest that seafloor heterogeneity, allowing diversified assemblages across different habitats, increases diversity and influence ecosystem processes at the regional scale, and BEF relationships at smaller spatial scales. We conclude that high-resolution seabed mapping and a detailed analysis of the species distribution at the habitat scale are crucial for improving management of goods and services delivered by deep-sea ecosystems. One of the emerging aims of marine ecology is to better understand which processes produce and maintain biodiversity in the deep sea and at which spatial scales these processes operate12345689101112The deep sea is the largest and most remote biome of the biosphere. The deep-sea floor, covering 65% of the Earth surface, has been considered for a long time to be, with few exceptions, highly spatially homogeneous; a kind of huge and flat soft-sediment desert15456171822The discovery of highly complex and diverse communities coexisting in relatively small areas34561819242526232829456153132333435363738394041424344The role of deep seafloor heterogeneity on the biodiversity turnover at small spatial scales  is largely unknown, yet. In fact, to date, most studies on the deep sea have analyzed benthic biodiversity variations assuming each habitat as a sampling unit, relatively homogeneous from an operational point of view, for instance by contrasting canyon vs. open slope sediments but ignoring the spatial effect of the sampling stations’ position within the two habitatsTheoretical ecology predicts that heterogeneous habitats allow more species to co-exist in a given area. In the deep sea, biodiversity is most often positively and exponentially linked with ecosystem functioning48In this study, we tested the null hypothesis by which biodiversity , ecosystem functioning and the relationships between biodiversity and ecosystem functioning do not vary across different seafloor morphologies occurring along the slope of the South Adriatic margin (Mediterranean Sea). This area is characterized by the co-occurrence in a relatively small area of a wide variety of different seabed morphologies including: sediment waves, erosional scours and furrows50To test our hypothesis in the deep sea, we selected the meiofauna, the numerically dominant component of deep-sea metazoan fauna, as this component provides a good proxy of the overall deep-sea benthic biodiversity52Since different seafloor morphologies, beside the different levels of habitat complexity, can offer different substrate characteristics and varying food availability to the meiofauna, we also explored the relationships between meiofauna (and nematode) abundance, biomass and biodiversity and sediment grain size and organic matter quantity and biochemical composition.−1  and the lowest in the furrows field . The vertical distribution of meiofaunal abundance and biomass varied among seabed morphologies, with an accumulation in the top first cm of the sediment in all stations, with the exception of the furrow and the sediment waves  than in all other seabed morphologies, whereas the lowest values occurred in furrow (n = 7 and SR = 52) and draped sediments (n = 6 and SR = 68). At the regional scale, 16 out of the 22 known meiofaunal taxa and a total of 250 nematodes species were found in the sediments of the study area. ANOSIM tests revealed no significant differences in the composition of meiofaunal communities and nematode assemblages among structures belonging to the same type of morphology (with the single exception for nematode species richness among two mud waves), nor among positions in selected seabed morphologies . HoweverAnoplostomatidae and Coninckiidae families were present exclusively in the scar, Bodonematidae were found only in the furrow, whereas Lauratonematidae, Rhabdodemaniidae and Symplocostomatidae were found exclusively in the sediment waves , while in the draped sediments Desmodora was dominant (14%) followed by Halomonhystera  are reported in Relationships between biodiversity and ecosystem functioning and efficiency across the investigated seabed morphologies are illustrated in During the last decade the intense exploration of the deep ocean, along with the refinement of the available technologies has revealed the presence of a wide variety of different topographic and morphological features of the sea bed1051The deep sea supports a rich and highly specialised benthic fauna that varies in composition and biodiversity across multiple spatial scales7236746181936374243We focused our study in an area off the SW Adriatic Margin selected for the presence of a large variety of seabed morphologies, which determine a marked heterogeneity at relatively small spatial scales , which makes this region ideal to test for the effects of spatial heterogeneity on deep-sea biodiversity and ecosystem functioning, and their relationships. The high seabed heterogeneity in this region is promoted by the presence of bottom currents, which have shaped the deep-sea Adriatic seafloor  and, in areas where they are particularly intense, have eroded the seafloor, leading to the formation of scours, moats or furrowsWorking in the deep-sea is extremely difficult for several reasons, including the high costs related to the use of infrastructures  and the difficulty in obtaining a highly replicated number of samples. These problems are even more evident when, as in the case of the present study, replicate samples are needed from specific habitat and seafloor morphologies of limited spatial extent. Despite these intrinsic limits, which hamper generalizations, we report here that meiofaunal abundance and biomass varied among the different seafloor morphologies investigated, whereas no significant differences were observed within the single seafloor morphology.The very low meiofaunal abundances observed in the furrow along the SW Adriatic margin, moulded by bottom currents, are analogues of deep-sea sites exposed to strong currents in the north east Atlantic583432Also the vertical distribution of meiofaunal abundance and biomass varied according to seafloor morphologies, with the presence of specific patterns in furrows and in sediment waves . These rAll of these results suggest that the importance of environmental variables in influencing meiofaunal abundance and biomass distribution depends also on the spatial scale considered. Moreover, our results suggest that different factors play a prominent role in control of meiofaunal variables at increasing spatial scales of observation . At the microscale, the distribution of meiofaunal variables is controlled by the physical-chemical characteristics of the sediment, whereas the seabed morphology, at larger spatial scales, and the availability of resources (i.e. productivity)7We show here that also meiofaunal taxa and nematode species richness vary among different seafloor morphologies, but not among different sampling units belonging to the same seafloor morphology nor among different positions within a single topographic structure. Furrows, scars, sand and draped sediments showed lower values of biodiversity  than all other seafloor morphologies. Firstly, this result suggests that the environmental factors that discriminate different seabed morphologies (including the distance from the coast/water depth) can influence in similar ways the α biodiversity both at species level and at the level of higher taxa. Moreover, our results also suggest that the environmental conditions characterizing clusters of different seabed morphologies are relatively invariant, so that richness of higher taxa, likewise nematode species richness, do not vary among different positions within each cluster , whereas they vary considerably among different seabed morphologies.Comesomatidae, Chromadoridae, Sphaerolaimidae and Desmodoridae, previously reported in deep-sea sediments of the South-Western Adriatic MarginSabatieria sp1). We also observed that Metasphaerolaimus sp2 and Wieseria sp3 were encountered only in the sand waves, while Pareurystomina sp1 and Platycoma sp1 were found exclusively in the sediments inside and outside the trough. Twenty-five species were exclusively found in mud wave sediments, 20 in the sand waves, 15 in the trough and in the other depositional structures and 4 in the scar. These results suggest that in the region under scrutiny the presence of different seabed morphology have allowed the establishment of highly diversified nematode communities, even in a relatively small area.Nematode species richness is influenced by a variety of processes, only in part operating across spatial scales56Recent developments of meta-community theory have investigated the interplay between regional and local processes in communities at the mesoscale636566674561819A large consensus about the importance of biodiversity in regulating the ecosystem functions that are responsible for the production of natural goods and services has been achieved and consolidated from both field and theoretical studies707374757648487348Seafloor integrity and its heterogeneity are important factors for maintaining a high deep-sea biodiversity8182The south-western Adriatic Margin  is marke550512, 20 cm depth). For the analyses of the organic components, the first cm of three sediment cores from independent box-corer deployments was frozen at −20 °C until analysis (within two weeks). One sediment corer was dedicated to sediment analyses. For meiofaunal analyses, at each site, three sediment cores from independent box-corer deployments were collected and sectioned into five layers . Since the analysis of the vertical distribution of meiofaunal assemblages generally showed the greatest abundance in the top first centimetre  and the cruise BARCA_07 . At each area, undisturbed sediment samples were collected using a NIOZ-type box-corer, with three independent deployments of the box-corer per area. From each box-corer sediment samples were collected using Plexiglas corer . Porosity (β) of sediments was calculated using the formula β  = 0.3105 + 0.0552ϕ −1. Since chlorophylls’ degradation products are typically dominant in deep-sea sedimentsChlorophyll-a and phaeopigment sedimentary contents were determined fluorometrically according to Lorenzen and Jeffrey−1, respectively, their sum reported as the biopolymeric carbon and assumed to represent the semi-labile fraction of sedimentary organic matter (OM)Protein, carbohydrate and lipid sedimentary contents were determined following spectrophotometric protocols−3). All meiofaunal animals were counted and classified under a stereomicroscope at the phylum level. Soft-bodied organisms were mounted on slides and viewed at 1,000× magnification. The abundance of the meiofauna is reported as individuals 10 cm−2. Meiofaunal biomass was calculated from the biovolume using the Andrassy formula 2 × C, where C is the approximate conversion factor for each meiofaunal taxon−3) to obtain the biomass (μg DW: μg WW = 0.25)Sediments were sieved through a 1,000-μm mesh, and a 20-μm mesh was used to retain the organisms. These were re-suspended and centrifuged three times with Ludox HS40  were randomly picked up from each of the three independent samples at each site and mounted on slides after formalin-ethanol-glycerol treatment. Nematodes were identified at the genus level and, whenever possible, at the species level, according to Platt and Warwick94e) and evenness as J2, where Pi = percent of species “ι“ in the total abundance). For each site, the expected number of species for a theoretical sample of 51 specimens, ES(51), was calculatedNematode diversity was measured by Shannon-Wiener diversity index  no buccal cavity or a fine tubular one -selective  feeders; (1B) large but unarmed buccal cavity-non-selective deposit feeders; (2A) buccal-cavity with scraping tooth or teeth-epistrate or epigrowth (diatom) feeders; (2B) buccal cavity with large jaws-predators/omnivoreset al.Five groups of ecosystem functions were proposed by Strong Mean, sorting, skewness and kurtosis sediment statistics were calculated arithmetically and geometrically (in metric units) and logarithmically (in phi units) using moment and Folk and Ward graphical methods, under the GRADISTAT v 4.0 software.ANOSIM and SIMPER tests were carried out to measure the similarities in the nematode and higher taxa compositions, separately, between different seafloor morphologies  and between distinct physical structures belonging to a single type of morphology . Variations in the composition of meiofauna and nematode communities were estimated as the percentage of dissimilarity, based on a Bray-Curtis similarity matrixTo evaluate the fraction of variance in meiofaunal abundance, biomass, taxa and species richness, and meiofaunal phylum and nematode species compositions explained by environmental covariates a non-parametric multivariate multiple regression analysis was carried outHow to cite this article: Zeppilli, D. et al. Seafloor heterogeneity influences the biodiversity–ecosystem functioning relationships in the deep sea. Sci. Rep.6, 26352; doi: 10.1038/srep26352 (2016).


Radiotherapy has been used to treat cancer and is required to treat many cancer patients. Although radiotherapy effectively inhibits the growth of cancer cells by inducing cell death, it is necessary to investigate its adverse effects such as promotion of cancer metastasis. It has been known that matrix metalloproteinases (MMPs), which play an important role in invasion of cancer cells, were induced by irradiation and are associated with the prognosis of some cancer patients. Recently, this induction of MMPs increased the shedding of natural killer group 2 member D ligands (NKG2DLs) and decreased surface expression of NKG2DLs on cancer cells. As a consequence, the cancer cells escape NK-mediated anti-cancer immunity. Irradiation induced the expression of MMPs. Previously, despite significant induction of NKG2DLs mRNA after irradiation, discordance appeared between mRNA and surface protein levels and the cytotoxic lysis of cancer cells. It was known that NK cells in cancer patients were inhibited by soluble NKG2DLs(sNKG2DLs), and MMPs had an important role in increasing sNKG2DLs. Therefore, it may be necessary to reduce the sNKG2DLs for NK cell-mediated immunotherapy. We inhibited the activity of MMPs using GM6001 or MMP inhibitor III after irradiation. We investigated whether the inhibition of MMPs affects the expression of NKG2DLs after irradiation in cancer cells. The expressions of MMP2 and ADAM10, which might promote invasion of cancer cells and evade NK-mediated anti-cancer immunity through reduction of surface protein levels of NKG2DLs, were increased by irradiation. It was suggested that treatment with MMP inhibitors might minimize the adverse effect of radiotherapy.


The design of three-dimensional (3D) in vitro models which ideally are supposed to mimic the in vivo stem cells microenvironment is potentially useful for inducing stem cell derived tissue formation. Biodegradable scaffolds play an important role in creating a 3D environment to induce tissue formation. The application of scaffolding materials together with stem cell technologies are believed to hold enormous potential for tissue regeneration. In this review, we provide an overview of application of tissue engineered scaffolds and stem cells for the development of stem cell-based engineered tissue replacements. In particular, we focus on bone marrow stem cells (BMSCs) and mesenchymal stem cell (MSCs) due to their extensive clinical applications.Stem cells are self-renewing cells that can be differentiated into other cell types. Conventional  Self-renewal is that characteristic of stem cells that maintains them in numerous cell cycle divisions, while potency defines the differentiation capability of stem cells into mature cell types. Mammalian stem cells are categorized based on the source they are derived from: embryonic stem (ES) cells, derived from blastocysts, and adult stem cells, found in adult tissues.2,6-8 Because of their ability to differentiate into all the cell types of an adult organism, ES cells are useful for cell-replacement therapies for a number of diseases including Alzheimer’s disease, Parkinson’s disease, spinal cord injury, diabetes and infarcted heart.9-12Embryonic Stem cells (ES) have the potential to differentiate into a number of different cell types. ES cell differentiation can be induced from cell aggregates, called embryonic bodies (EBs), which initiate many developmental processes and generate derivatives of the three primary germ layers .13-17 Bone marrow contains at least two kinds of stem cells. One population, called hematopoietic stem cells, form all types of blood cells in the body. A second population, called bone marrow stromal cells, was discovered a few years later. Bone marrow stromal cells  give rise to a variety of cell types: bone cells (osteocytes), cartilage cells (chondrocytes), fat cells (adipocytes), and other kinds of connective tissue cells such as those in tendons.2,3 The primary roles of adult stem cells in a living organism are to maintain and repair the tissue in which they are found and exhibit the ability to form specialized cell types of other tissues, which is known as transdifferentiation or plasticity.13,18Adult stem cells are a class of stem cells comprised of undifferentiated cells found in many tissues of an adult organism and have an extensive self-renewal capability and the ability to differentiate into various specialized cell types .19 Considering the usage of cells in the body, it is no doubt that a sufficient supply of nutrients and oxygen to the transplanted cells is vital for their survival and functional maintenance.20,21 Also without a sufficient supply, only a small number of cells pre-seeded in the scaffold or migrated into the scaffold from the surrounding tissue would survive. In conventional cell culture such as static tissue culture dish (2D), the initial rate of cell growth is higher, but the proliferation stops once the cells reach confluence. In order to overcome supply limitations, porous materials with (3D) structures have been generated because of their larger surface for cell attachment and proliferation relative to 2D materials. They are also preferable in assisting with the formation of 3D cell constructs which may resemble the structure and function of body tissues. Moreover, diffusion of nutrients, oxygen and bioactive factors through 3D constructs is sufficient for survival of large numbers of cells for extended periods of time.22,23Because functional tissues require certain mechanical and structural properties; tissue engineering has aimed at performing specific biochemical functions using cells in artificial support systems. One should consider the fact that generating cell-laden tissue engineered constructs has the capability of maintaining the proliferation and differentiation activity. Therefore, design of engineered tissues from cell proliferation and differentiation is one of the key objectives of tissue engineering.22 Previous reports indicated basic fibroblast growth factor (bFGF) promoting angiogenesis process.22,24 The growth factors stimulate the appropriate cells , already present in the body, to migrate from the surrounding tissue, proliferate, and finally differentiate into blood vessels. However, bFGF has a very short half-life when injected and is unstable in solution. To overcome these problems, bFGF was encapsulated within alginate, gelatin, agarose/heparin, collagen, and poly (etyhylene-co-vinyl acetate) carriers.25,26 One possible way for enhancing the in vivo efficacy is to achieve its controlled release over an extended time period by incorporating the growth factor in a polymer carrier. If this carrier is biodegraded, harmonized with tissue growth, it will work as a scaffold for tissue regeneration in addition to a carrier matrix for the growth factor release. Also presence of extracellular matrix (ECM) and soluble factors (that induce vascuarization and differentiation of stem cells embedded into these constructs) addresses some of the limitations for application of tissue engineering constructs. Rapid formation of a vascular network at the transplanted site of cells seems promising for providing stem cells with the vital supplies. This process of generating new microvasculature, termed neovascularization, is a process observed physiologically in development and wound healing.27 Ideally, a polymeric scaffold in tissue engineering should have the following characteristics: i) Holding appropriate surface properties promoting cell adhesion, proliferation and differentiation; ii) Biocompatiblity; iii) High porosity, and a high surface-area to volume ratio, with an interconnected pore network for cell growth and flow transport of nutrients and metabolic waste, iv) Sufficient mechanical properties and any in vivo stresses.27-31 Xie et al. reported that the initial rate of cell growth is higher for the 2D culture, but once the cells reach confluence, their proliferation stops.32 Other reports have also demonstrated that cell proliferation in the 3D scaffolds is superior to the 2D scaffolds. Therefore, the cell growth in the 3D scaffolds continues for longer time periods than that of 2D scaffolds.33,34Synthetic materials demonstrate interesting characteristics since their chemical and physical properties  can be specifically optimized for a particular application. The Structure of polymeric scaffolds are endowed with a complex internal architecture and porosity that provide sites for cell attachment and maintenance of differentiation function without hindering proliferation.et al.35 Therefore, the scaffold materials used in tissue engineering need to be chemically functional in order to promote tissue regeneration as ECM does. ECM proteins such as Collagen and Elastin are made from fibers in dimensions smaller than micrometers.35 It seems that artificial nanoscale fibers have great potential application in the field of biomaterials and tissue engineering. The initial report showed that nanoscale features influence cell behaviors.36 Nanoscale surface topography has been found to promote osteoblast adhesions.37 It has been demonstrated that osteoblast adhesion, proliferation, alkaline phosphatase activity, and ECM secretion on carbon nanofibers increases with decreasing fiber diameter in the range of 60-200 nm, whereas the adhesion of other kinds of cells such as chondorocytes, fibroblasts, and smooth muscle cells remains non-influenced.38,39 It has been believed that the nanoscale surfaces affect the conformation of adsorbed adhesion proteins such as vitronectin, thus affecting the cell behaviors. In addition, the nanoscale dimensions of cell membrane receptors such as integrins should also be considered.40The design of materials that can regulate cell behavior such as proliferation and differentiation is a key component for the fabrication of tissue engineering scaffolds. From the view point of immune system response of the body, the implanted biomaterials should mimic the structure and biological functionality of native extracellular matrix (ECM), both in terms of chemical composition and physical structure as reported by Ma 26Cell proliferation in 3-D scaffold, needs oxygen and nutrition supply. Therefore, the 3-D scaffold materials should provide such an environment for cells. The artificial scaffolds formed by self-assembling molecules not only provide suitable support for cell proliferation but also serve as a medium through which diffusion of soluble factors and migration of cells can occur. The result of the cell attachment and proliferation revealed that diffusion of nutrients, bioactive factors, and oxygen through these highly hydrated networks is sufficient for survival of large numbers of cells for extended periods of time.26The 3D scaffolds are capable of differentiating a single progenitor cell population into particular lineage either due to bulk incorporation of soluble factors within the scaffolds or due to exogenous delivery of chemicals, hormones, and growth factors in culture medium. Therefore, design of patterned scaffolds with the ability to develop multiple lineages and hybrid organ structures could provide promising alternatives.41-43Metal scaffolds like titanium are bio-compatible and suitable for hard-tissue applications, such as the growth and differentiation of rat dental pulp progenitor cells into odontoblast-like cells. In order to improve their efficacy, metal scaffolds can be covered with biological compounds, like titanium fibers pre-coated with ECM components that support the osteogenic differentiation of rats’ BMSCs.44,45Another type of scaffolds is made of organic materials that provide a bio-mimetic environment for stem cells. Human BMSCs regenerate bone in marine sponge skeletons, cartilage in silk fibroin scaffolds, and adipose tissue in gelatin. To provide mechanical strength, biological agents influencing stem cell fate could be added to the scaffold’s compounds. Marine sponge skeletons, for example, contain these cell adhesion proteins: fibronectin, collagen and gelatin.26 It has been reported that the attachment, proliferation and ECM production of human and rat BMSC, are promoted while copolymers of poly (e-caprolactone) and poly (ethylene glycol) are blocked. Ligand binding and controlled release of regulatory factors can improve the degree of control over spatial organization and differentiation of stem cells within scaffolds. Osteogenic differentiation of rat BMSCs was enhanced into an oligo (polyethylene glycol) scaffold that incorporated peptides containing the cell-binding sequence arginine-glycine-aspartate in the absence of soluble factors like dexamethasone. Moreover, controlling the release of regulatory molecules from porous poly  scaffold inducing rabbit BMSCs within the scaffold to mineralize in vitro into bone.42,44Synthetic polymers provide greater control over the mechanical and degradation properties of the tissue scaffold. For example, self-assembling peptide scaffolds contain highly flexible nano-fibers that support the differentiation of rat liver progenitor cells into functional hepatocyte-like spheroinods.The application of scaffolding materials together with stem cell technologies are believed to hold enormous potential for tissue regeneration. In this review, we provide an overview of application of tissue engineered scaffolds and stem cells for the development of stem cell-based engineered tissue replacements. In particular, we focus on bone marrow stem cells (BMSCs) and mesenchymal stem cell (MSCs) due to their extensive clinical applications.