Hypertrophic cardiomyopathy (HCM) is a common myocardial disease characterized by otherwise unexplained left ventricular hypertrophy. The main cause of disabling symptoms in patients with HCM is left ventricular outflow tract (LVOT) obstruction. This phenomenon is multifactorial, determined both by anatomical and functional abnormalities: myocardial hypercontractility is believed to represent one of its major determinants. The anatomical anomalies are targeted by surgical interventions, whereas attenuating hypercontractility is the objective of old and new drugs including the novel class of allosteric myosin inhibitors. This review summarizes the current treatment modalities and discusses the emerging therapeutical opportunities focusing on the recently developed cardiac myosin ATPase inhibitors Mavacamten and CK-274. Novel surgical and interventional approaches are also discussed. Hypertrophic cardiomyopathy (HCM) is a global genetic heart disease with 1:500 prevalence in the general population, defined by left ventricular hypertrophy in the absence of abnormal loading conditions . It showAlthough the LV anatomical and functional characteristics may be diverse, a recurrent scenario may be delineated. In obstructive HCM, the protruding leaflets of the mitral valve are caught by the outgoing LV flow misdirected by septal hypertrophy and, due to the consequent systolic anterior movement (SAM), make contact with the septum very early in systole, starting a vicious circle in which the creation of a gradient pushes the valve further into the outflow, increasing the gradient, and so on. Loss of mitral leaflet coaptation due to SAM leads to mitral regurgitation. Several morphological and functional abnormalities conjure to determine LVOTO including: elongated mitral valve leaflets, anterior mitral tenting by displaced, hypertrophied papillary muscles and retracted secondary chordae, reduced LVOT size, accessory LV muscle bundles, reduced LV cavity size and hyperdynamic LV . RecentlBased on this rationale, current medical therapy for symptomatic obstructive HCM is based on the use of drugs with negative inotropic and chronotropic effects. Beta blockers have been the mainstay for five decades . Beta bDisopyramide is a class Ia antiarrhythmic drug with negative inotropic properties, more powerful than beta blockers and verapamil in controlling LVOTO . The bioMyosins are molecular propellers converting the chemical energy of ATP hydrolysis into the mechanical force necessary for muscle contraction . In a sip = 0.0005). This result was associated with marked reduction in post exercise LVOT gradient over the 30 weeks of treatment, compared to no change in the placebo group  and improvement in functional capacity expressed by a greater increase in both pVO2  and NYHA functional class . Furthermore, treatment with Mavacamten was associated with an amelioration in patient-reported outcomes including quality of life  and HCM core symptoms, evaluated through the newly developed, disease-specific Hypertrophic Cardiomyopathy Symptom Questionnaire Shortness-of-Breath (HCMSQ-SoB) subscore . Nearly three-fourths of the patients on Mavacamten showed an LVOT gradient reduction below the guideline-defined threshold for invasive therapy , nearly 60% experienced a complete relief from obstruction  and about 30% reached a complete relief from both symptoms and obstruction . Clinical improvement was associated with marked reduction in serum levels of N-terminal pro-brain natriuretic peptide (NTproBNP) and troponin I, two predictors of long-term outcome in HCM [In the proof-of-concept phase 2 PIONEER-HCM trial, treatment with Mavacamten in oHCM led to improvements in post-exercise LVOT gradients, exercise capacity and symptoms, and was generally well tolerated, with most adverse effects being mild or moderate, self-limiting and judged to be unrelated to the study drug . Followie in HCM .These results were achieved at the expense of a small average reduction in ejection fraction  and only five patients underwent protocol-driven temporary treatment discontinuation for left ventricular ejection fraction (LVEF) <50%; the latter normalized in all following wash-out, allowing study completion on a lower dose.Mavacamten showed a favorable safety profile, overall comparable to placebo. Notably, the number of patients with severe adverse events and the absolute number of severe adverse events were actually lower in the active treatment arm compared with placebo. Two patients on Mavacamten developed stress cardiomyopathy , for reasons currently unknown and requiring further investigation.Overall, EXPLORER-HCM represents a pivotal trial, in that it demonstrated for the first time the potential of a targeted molecular approach based on a solid pre-clinical rationale in HCM. Although the study was necessarily designed on surrogate end-points, due to the low rate of “hard” cardiovascular endpoints  in this disease, its implications suggest a profound effect on several aspects of the disease, allowing hopes for long term efficacy and impact on natural history. Study limitations included the lack of information regarding disopyramide co-administration and the exclusion of severely symptomatic (NYHA class IV) patients, both areas currently under investigation .Very recently, in the EXPLORER-HCM cardiac magnetic resonance substudy, Mavacamten treatment was shown to induce reverse cardiac remodeling, reducing LV mass index and maximum LV wall thickness. Moreover, patients on Mavacamten presented a greater reduction in LV atrial volume index, reflecting hemodynamic improvement and a decrease in LV filling pressure. These structural changes paralleled the favorable reduction in circulating biomarkers .Finally, preliminary data suggest a beneficial effect of Mavacamten also in non-obstructive HCM patients, as seen in the phase 2 MAVERICK-HCM trial. In this study, exploratory analyses showed a significative reduction in NT-proBNP, although only one-third of patients with a more severe phenotype improved in terms of NYHA class and pVO2 . Main stAnother cardiac myosin ATPase inhibitor, CK-3773274 (CK-274), is currently under investigation in the ongoing phase 2 REDWOOD-HCM trial. CK-274 has a similar mechanism of action to Mavacamten, stabilizing myosin in a weak actin-binding conformation , but preTargeted therapies are being developed for the broader spectrum of “sarcomeric” disease, beyond the borders of HCM and involving its “opposite” dilated cardiomyopathy. The selective cardiac myosin activator Omecamtiv mecarbil acts by stabilizing the myosin head in the open state , increasFinally, the same molecular development pipeline is bringing hopes to patients with neuromuscular diseases, particularly with amyotrophic lateral sclerosis (ALS). Fast skeletal muscle troponin activators (FSTAs) have been shown to increase muscle force by slowing the off rate of calcium from troponin, thus increasing calcium sensitivity . After tSeptal myectomy is the gold-standard strategy for the treatment of drug-refractory symptoms in oHCM patients . The inThe timing of intervention is an important and still unresolved issue. We have recently shown that a prolonged exposure to LVOTO is detrimental, even in the absence of severe symptoms. Specifically, a delay of more than five years from first gradient detection to septal reduction therapy (SRT) was associated with doubling of the risk of cardiovascular mortality and disease progression . In a reThe cardiovascular risk factors control in patients with HCM should be strict in order to avoid the development of a double, ischemic and inherited, cardiomyopathy . In factThe stepped management proposed by the recent AHA/ACC guidelines defines the best of possible worlds in HCM, balancing risks and benefit in a long-term perspective . In the ASA is the first option in patients not eligible for surgery . This aAV sequential pacing was considered an obsolete technique until long term studies reported a sustained effect on LVOT gradient reduction ,61. In tIn patients with refractory HF with reduced ejection fraction and chronic severe secondary mitral regurgitation, edge to edge mitral valve repair with the use of the MitraClip system  is a reasonable approach . This tLVOT obstruction is the most prevalent cause of heart failure in patients with HCM, and its relief is a fundamental therapeutic aim requiring a concerted effort by physicians and surgeons, fulfilling the “HCM Heart Team” concept . Ground-Hypertrophic cardiomyopathy (HCM) is a genetic heart disease characterized by various degrees of left ventricular hypertrophy, hyperdynamic contractility and mitral valve abnormalities that may lead to left ventricular outflow tract obstruction (LVOTO).LVOTO is the main cause of disabling symptoms and heart failure in HCM patients and its relief is a fundamental therapeutic aim requiring a concerted effort by physicians and surgeons.From a solid pre-clinical rationale, a targeted therapy for LVOTO represented by allosteric cardiac myosin inhibitors has been developed. The new drugs have been studied in recent clinical trials that showed an improvement in functional capacity, a reduction in LVOT gradient and related symptoms evaluated by both physicians and patients.The progress in medical therapy parallels the advance towards a tailored surgical approach that remains the gold-standard for the treatment of drug-refractory symptoms in obstructive HCM patients.The new targeted medical therapies in HCM might have set the basis for the emergence of precision medicine in cardiomyopathies.


Aging is the primary risk factor for progressive loss of function, onset of disease, and increased vulnerability to negative health-related outcomes. These clinical manifestations arise from a decline in mitochondrial and metabolic processes considered the hallmarks of aging. Collectively, these changes can be defined as age associated cellular decline (AACD) and are often associated with signs and symptoms such as fatigue, reduced strength and low physical activity. This symposium will explore mechanisms, clinical signs, and emerging nutritional interventions for AACD. Dr. Feige’s presentation will serve as an introduction by highlighting mechanisms underlying functional declines in skeletal muscle with aging. He will discuss the Multi-Ethnic Molecular determinants of Sarcopenia (MEMOSA) study, which found impaired mitochondrial bioenergetic capacity in skeletal muscle of older adults with sarcopenia compared to age-matched controls, and identified mitochondrial function as a key target for intervention. Dr. Guralnik will discuss the connection between cellular changes and clinical manifestations of AACD. He will report on an expert consensus study group which developed an initial framework to identify self-reported symptoms and observable signs of AACD in adults over50 years. Lastly, Dr. Singh will discuss the evidence for nutritional interventions to address sources of AACD, focusing on those targeting mitochondrial dysfunction. Recent research on dietary interventions with urolithin A (an activator of mitophagy) and nicotinamide riboside (an NAD+ booster) will be reviewed. Overall, this symposium will highlight key mechanisms and clinical signs of AACD, and the potential for novel nutrition interventions to support cellular function and healthy aging.


Osteoarthritis (OA) is a prevalent musculoskeletal disease resulting in progressive degeneration of the hyaline articular cartilage within synovial joints. Current repair treatments for OA often result in poor quality tissue that is functionally ineffective compared to the hyaline cartilage and demonstrates increased failure rates post-treatment. Complicating efforts to improve clinical outcomes, animal models used in pre-clinical research show significant heterogeneity in their regenerative and degenerative responses associated with their species, age, genetic/epigenetic traits, and context of cartilage injury or disease. These can lead to variable outcomes when testing and validating novel therapeutic approaches for OA. Furthermore, it remains unclear whether protection against OA among different model systems is driven by inhibition of cartilage degeneration, enhancement of cartilage regeneration, or any combination thereof.Understanding the mechanistic basis underlying this context-dependent duality is essential for the rational design of targeted cartilage repair and OA therapies. Here, we discuss some of the critical variables related to the cross-species paradigm of degenerative and regenerative abilities found in pre-clinical animal models, to highlight that a gradient of regenerative competence within cartilage may exist across species and even in the greater human population, and likely influences clinical outcomes.A more complete understanding of the endogenous regenerative potential of cartilage in a species specific context may facilitate the development of effective therapeutic approaches for cartilage injury and/or OA. As a leading cause of disability and morbidity worldwide, osteoarthritis (OA) is a degenerative joint pathology associated with significant health and economic burden to patients and society , 2. The The articular cartilage is an intricate and remarkable tissue that provides the biomechanical properties and a low friction surface necessary for the proper function of synovial joints , 4. WhilAttempts have been made to circumvent this poor intrinsic regenerative ability of cartilage and protect it from further degradation after damage or disease, by promoting an environment that is chondroprotective (preventing cartilage breakdown) and/or chondro-inductive (restoring cartilage) . These iThe therapeutic potential of cell-, drug- or surgical-based interventions focused on cartilage injury and OA is commonly assessed using pre-clinical animal models. Notably, not only different species but also strains at various ages and contexts of joint damage  are employed. All these variables can influence the regenerative and degenerative responses, create a spectrum of outcomes Fig.  and haveMoreover, previous studies have reported that the rate of progression and severity of cartilage degeneration and OA-related changes in the joint differ among commonly used trauma-induced models , 20, sucTherefore, in this review, we provide an overarching view of some of the key variables and their impact on cartilage tissue regeneration and degeneration. Also, we discuss how understanding the baseline of the endogenous regenerative capacity within pre-clinical models, and its modulation within a conducive environment is essential and should be integrated into the assessment of therapeutic approaches for cartilage injury and OA, in a context-specific manner.While most tissues in mammals often fail to regenerate, as opposed to more primitive organisms such as amphibians, a certain inherent capacity to respond to injury is present. Regenerative competence after distal digit tip amputation, for instance, has been reported in mice , 24 and Various animal models have been employed in cartilage injury and OA-related studies, including mice, rats, guinea pigs, rabbits, dogs, and larger animals such as goats and horses –36. EachRabbits have been shown to possess robust intrinsic healing compared to humans, with previously reported wound regeneration of ear biopsy punch , 38 and While a comprehensive genome screening of the greater human population remains elusive, mouse studies can provide some insights into how genetic variations might be associated with OA resistance or vulnerability . Murine Overall, few mammalian model systems demonstrate robust cartilage regeneration in vivo. In mice, it has been observed in the Murphy Roths Large (MRL/MpJ) strain, whose superior ability to regenerate cartilaginous tissue was first demonstrated in the ear pinnae after through-and-through punch wound  and late. Of note, disturbance of the cell cycle machinery including increased DNA damage and decreased levels of p21 protein, known as a critical cell cycle regulator, were identified in cells derived from MRL/MpJ mice. Later, the enhanced healing potential of through-and-through ear injuries was observed in p21 knockout (p21−/−) mice, suggesting the lack of p21 is at least partially responsible for the enhanced regenerative phenotype seen in MRL/MpJ mice [Subsequent studies showed that MRL/MpJ regenerative abilities extend to other tissues , 47, andMpJ mice . This haMpJ mice . HoweverMpJ mice  and inflMpJ mice , in addiMpJ mice . OverallAcomys), including scar-free healing of auricular cartilage after ear biopsy punch [Acomys from scarring in wild-type controls [More recently, multi-tissue regeneration has been identified in the African spiny mice  , the comThe age of the animal is always an essential consideration, as it is generally agreed that younger animals have increased intrinsic cartilage regenerative potential compared to adults. Pre-clinical studies to date have demonstrated correlations between aging and regenerative decline within mammals , 40. YetAs for disease development, studies investigating correlations between spontaneous OA and aging have pinpointed the increase in senescent chondrocytes with age as an essential contributing factor to cartilage degeneration –60. AddiHuang et al. described age-dependent structural changes post-trauma in the articular cartilage and subchondral bone of mice, with OA features appearing earlier and being more pronounced in the aged groups [Loeser et al. have previously reported that age also alters gene expressions in the whole joint, even in the absence of injury, highlighting this likely affects the tissue response after a traumatic event [When comparing age paradigms in different strains of mice, it has been shown that OA severity in aged mice is greater than young mice following injury , 67, 68.ic event , 60. ForSimilarly, Usmani et al. explored the therapeutic potential of inhibiting TGFα, a growth factor previously implicated in OA pathogenesis, within the context of spontaneous and post-traumatic OA. The latter employed a DMM surgery model to induce cartilage injury in young (10-week old), as well as aged (6-month old) mice. The authors found that TGF-α deficiency did not protect mice from the development of spontaneous OA and that its effect in trauma-induced OA is age-dependent, whereby only young mice were protected from OA progression . UltimatResearch focusing on cartilage degeneration typically employs animal models of spontaneous or post-traumatic OA to elucidate the mechanisms of onset and progression of the disease Table . As prevHaase et al. have recently compared two surgically induced PTOA models in C57BL/6 mice, specifically DMM and transection of the medial collateral ligament (MCL-MM) . Mice thOf note, surgical models of PTOA are invasive, with the surgery itself inducing inflammation, and possibly degenerative changes in the joint environment, thereby diminishing our ability to understand the mechanisms underlying the disease phenotype. Therefore, non-invasive approaches mimicking PTOA have been developed, which involve mechanical overloading of the joint to induce cartilage lesions Table . Some exOther examples of induced OA models, yet non-traumatic in nature, include chemically and diet-induced models Table . ChemicaWhile it is broadly assumed that articular cartilage has little to no intrinsic repair at a population level, what if cartilage regeneration can outplace cartilage degeneration in some proportion of the population. This hypothesis is supported by results from previous clinical studies, wherein only about 50% of human patients that undergo cartilage or joint injury develop OA over time , 87. In −/− mice seem to be vulnerable to cartilage damage following DMM surgery [Despite their genetic predisposition to the development of spontaneous OA, STR/ort mice are less prone to cartilage lesion formation after joint compressive overloading than CBA mice , suggest surgery , despite surgery .Direct cartilage injury is commonly used to study the tissue regenerative potential by producing a partial or a FTCD, focally or longitudinally in the trochlear groove, that can reach into the subchondral bone Table  18, 44,,44, 90. As alluded to, models of direct cartilage injury and PTOA reflect the duality of cartilage regeneration and degeneration Fig. . In the However, to elucidate the biological mechanisms promoting a protective phenotype in the latter, it is necessary to understand whether the intervention inhibited degeneration and/or promoted regeneration of the cartilage. In which case, the causative role associated with an intrinsic healing potential and the chosen therapeutic intervention should also be investigated. Intra-articular injection of kartogenin, for instance, has been shown to protect mice against the development of OA following surgically-induced trauma . Such ou−/− mice from cartilage degeneration [−/− mice showing decreased pain and comparable histopathological scores to CCR2−/− and wild-type controls after induced-PTOA [−/− mice, associated with less severe cartilage degeneration compared to the other mouse groups [Recent studies investigating the involvement of chemokines and correlated inflammatory component in OA pathogenesis have linked the CCL2/CCR2 signaling axis, mainly known for its role in monocyte recruitment, to trauma-induced and age-associated OA phenotypes in humans and rodents –95. Inteneration . Expandiced-PTOA . Yet, ste groups .−/−, but not CCL2−/− nor CCL2−/−CCR2−/− mice display enhanced cartilage regeneration following FTCD [Likewise, Raghu et al. demonstrated that CCL2 deficiency was protective of cartilage degeneration, and promoted a significant decrease in macrophage infiltration, inflammation and expression of matrix-degrading molecules . Howevering FTCD . CollectOverall, studies providing a comprehensive view of how specific treatments contribute to the prevention of cartilage degeneration, as well as to the enhancement of its regeneration are scarce , 22; howIt is widely accepted that several risk factors can alter the progression of OA such as obesity, joint trauma, improper mechanical loading, and aging. A recent review by Mimpen and Snelling has suggested that heterogeneities in endotypes that predispose to OA onset and progression should be considered in patient selection and outcome assessment in clinical trials . We suggWe are encouraged by recent findings on the topic, suggesting that the regenerative capacity of cartilage is variable and depends on where it resides in the human body, being more robust in the ankle joints . We beli


Cognitive impairment is one of the major symptoms in most neurodegenerative disorders such as Alzheimer’s (AD), Parkinson (PD), and Huntington diseases (HD), affecting millions of people worldwide. Unfortunately, there is no treatment to cure or prevent the progression of those diseases. Cognitive impairment has been related to neuronal cell death and/or synaptic plasticity alteration in important brain regions, such as the cerebral cortex, substantia nigra, striatum, and hippocampus. Therefore, compounds that can act to protect the neuronal loss and/or to reestablish the synaptic activity are needed to prevent cognitive decline in neurodegenerative diseases. Pituitary adenylate cyclase-activating polypeptide (PACAP) and vasoactive intestinal peptide (VIP) are two highly related multifunctional neuropeptides widely distributed in the central nervous system (CNS). PACAP and VIP exert their action through two common receptors, VPAC1 and VPAC2, while PACAP has an additional specific receptor, PAC1. In this review article, we first presented evidence showing the therapeutic potential of PACAP and VIP to fight the cognitive decline observed in models of AD, PD, and HD. We also reviewed the main transduction pathways activated by PACAP and VIP receptors to reduce cognitive dysfunction. Furthermore, we identified the therapeutic targets of PACAP and VIP, and finally, we evaluated different novel synthetic PACAP and VIP analogs as promising pharmacological tools. Cognition is the result of the formation of functional neuronal circuits in many cerebral areas governed by a dynamic phenomenon named synaptic plasticity. People suffering from neurodegenerative diseases commonly present cognitive impairment, such as dementia, deficits in learning and attention, or incomplete executive function among others, affecting the daily life of patients and their families. This impairment is mediated by the extracellular or intracellular accumulation of protein aggregates that disrupt synaptic plasticity leading to neuronal dysfunction and/or neuronal death. Several mechanisms have been involved in neuronal plasticity disturbance and neuronal cell death, such as inflammation, excitotoxicity, oxidative stress, and neurotrophic deprivation. These mechanisms affect genetic expression through the activation/inhibition of some pathways and transcription factors. The result of altered genetic expression is the disruption of structural and functional synaptic plasticity and/or the viability of neurons. Thus, molecules able to promote synaptic plasticity or neuronal viability by the interaction and inhibition of these mechanisms in brain areas related to learning and memory could be interesting therapeutic compounds to stop the cognitive decline in neurodegenerative diseases.Pituitary adenylate cyclase-activating polypeptide (PACAP) and vasoactive intestinal polypeptide (VIP) are well-known neuropeptides that exert a potent neuroprotective effect through the activation of different signaling pathways and transcriptional-genetic activity  and multiple sclerosis (MS) are two diseases that affect both the brain and spinal cord nervous tissue. ALS is marked by progressive degeneration of upper and lower motor neurons while MS is characterized by demyelination due to an autoimmune response. Although ALS and MS have been traditionally viewed as diseases of the motor system, cognitive impairment also occurs in these pathologies  than VPAC1R and VPAC2R transcripts /protein kinase A (PKA), phospholipase (PLC)/protein kinase C (PKC), mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3 kinase (PI3K)/Akt transduction pathways  receptor. NMDA receptors play an essential role in synaptic plasticity and synaptogenesis 6, Nle17] PACAP (1–27) analog on cognitive deficits in neurodegenerative models has not been evaluated yet. Shorter fragments such as the amidated PACAP23 have shown their neuroprotective action in vitro (Lamine et al., in vivo, in particular after intranasal injection. Indeed, the C terminal part of PACAP seems to be important for its transportation across the blood-brain barrier (Banks et al., PACAP is metabolized mainly by dipeptidyl peptidase IV (DPP IV; Zhu et al., in vivo. Using two rat models of developmental retardation, water maze experiments showed that SNV improves cognitive functions (Gozes et al., Regarding VIP, its susceptibility to endopeptidases is also well known (Deng and Jin, Altogether, several analogues more stable and selective than PACAP and VIP have been designed to increase the therapeutic activity and applicability. However, their role in cognitive dysfunction in neurodegenerative diseases is poorly known. Therefore, further research and some clinical trials are needed to ensure the therapeutic potential of these promising analogs.IS-T, NC-L, and XX wrote the manuscript. IS-T, DV, and XX revised the literature. Supervision and conceptualization was performed by DV and XX. Editing was performed by XX.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.


Characteristics  of young adults with COVID-19 during March 1–July 18, 2020, and within Winnebago County, were obtained from Wisconsin’s Electronic Disease Surveillance System.By mid-June, after the Safer at Home Emergency Order was invalidated, Winnebago County experienced an increase in COVID-19 cases, with the largest increase among young adults . During Among the 13 young adults interviewed, nine were women, all were employed, and all were either enrolled in college or had graduated from college within the last year. Common themes that emerged during interviews as drivers of behavior were social or peer pressure, social interactions, attitudes regarding public health guidance, perceived severity of disease outcome, perceived responsibility to others, workplace COVID-19 mitigation measures, absence of countywide measures, identifying a trusted source for COVID-19 information, and exposure to misinformation, conflicting messages, or opposing views regarding masks . In the Among interviewed business owners (nine) and community leaders (eight), all business owners identified local health officials as trusted sources for COVID-19 information, yet a few community leaders did not. Further, many business owners and community leaders reported exposure to misinformation, conflicting messages, or opposing views regarding the need for or effectiveness of masks. Business owners indicated they had implemented some control measures ; however, many reported discontinuing mask-wearing requirements for reasons such as not wanting to offend customers or perceived competition with similar establishments. Business owners perceived the absence of a countywide mask ordinance as a barrier to reimplementing mask-wearing requirements within their establishments and some spontaneously indicated that if a mask ordinance was implemented, they would comply.Wisconsin’s Electronic Disease Surveillance System data indicated social interactions and workplace and community transmission likely contributed to the spread of COVID-19 among young adults in Winnebago County. Nearly three quarters (72%) of young adults with COVID-19 were employed, and over one half (58%) worked outside of the home while contagious, increasing the risk for transmitting SARS-CoV-2 to the broader community. Among young adult interviewees with jobs that entailed interaction with the public, many voiced concerns about workplace exposure, underscoring the importance of businesses implementing control measures  consistent with published guidance,Some young adults admitted to not wearing a mask when socializing with friends, which might indicate a sense of security when interacting with friends. Moreover, the expectation that they would likely be fine if they contracted COVID-19, coupled with social or peer pressure, might help explain transmission patterns among young adults. Although young adults perceived a low severity of disease outcome for themselves, many expressed concerns about transmitting SARS-CoV-2 to loved ones at risk and to the broader community. Having a sense of responsibility to others might explain why young adults reported wearing masks when shopping and why most held positive views of masks. However, when not in physical contact with loved ones at risk, young adults might choose to not wear a mask or to attend larger gatherings with peers who might also perceive a low severity of disease outcome for themselves. Exposure to misinformation and conflicting messages regarding masks might make it difficult to know what information to trust, underscoring the importance of providing clear and consistent messages during an outbreak  that prevent the spread of COVID-19. Masks are an effective tool to prevent the spread of COVID-19 (Young adults represent an increasingly large proportion of U.S. COVID-19 cases.In Winnebago County, Wisconsin, perceived low severity of disease outcome; perceived responsibility to others; peer pressure; and exposure to misinformation, conflicting messages, or opposing views regarding masks were identified as drivers of behaviors that might influence risk for COVID-19 exposure among young adults.Identifying factors that influence risk for COVID-19 exposure and framing messaging to target those factors could help persuade young adults to adhere to public health guidelines that prevent the spread of COVID-19. Providing clear and consistent messages regarding the need for and effectiveness of masks could help increase widespread adoption of evidence-based guidance.


In this review, we discuss current state-of-the-art strategies for generating hPSC-derived endodermal organoids including stomach, liver, pancreatic, small intestine, and colonic organoids. We also review the advantages of using this system to model various human diseases and evaluate the shortcomings of this technology. Finally, we emphasize how other technologies, such as genome editing and bioengineering, can be incorporated into the 3D hPSC-organoid models to generate even more robust and powerful platforms for understanding human organ development and disease modeling.Recent advances in development of protocols for directed differentiation from human pluripotent stem cells (hPSCs) to defined lineages, in combination with 3D organoid technology, have facilitated the generation of various endoderm-derived organoids for  An organoid is a mini-organ formed in vitro in 3D culture from a single cell or group of cells that possesses the capability to self-organize, self-renew, and differentiate to different cell types associated with its corresponding organ, in response to appropriate signals. In the 1950s and 1960s, some studies referred to organoids as ‘intracellular organelles’, a term that is now obsolete  components that enabled investigators to culture differentiated cells in 3D. Compared to 2D culture, 3D culture plays an important role in supporting cell growth, patterned cell differentiation, and development of more complex organ-like structures ed in 2D . Neverthed in 2D  or mammaed in 2D  were allBetween 1963 and 1977, three scientists isolated a gelatinous basement membrane while studying a chrondrosarcoma tumor that produced excessive ECM, and that was subsequently named after them as the Engrelbreth‒Horm‒Swarm (EHS) sarcoma. The ECM generated from the EHS sarcoma is now known as Matrigel, which is enriched in laminin, collagen IV, and fibronectin. With the discovery of these distinct ECM components, numerous groups independently demonstrated the importance of ECM in regulating gene expression in various primary cell types and therefore controlling the differentiation states and functions of these primary cells. In 1991, + intestinal stem cell isolated from the adult mouse intestinal crypt is capable of forming a complex in vivo-like structure comprised of different intestinal cell types. In less than a decade, scientists have successfully generated organoids that mimic the brain, retina, kidney, liver, stomach, pancreas, intestine, and several other organs. For detailed information on the history of organoid development and use, readers can refer to a comprehensive review written by With progressive understanding of the importance for interplay between growth factors, morphogens, and ECM in morphogenesis combined with advances in stem cell isolation and differentiation strategies, different methods have been devised for 3D culture of cells from different organs. First reported in 2008, Sasai and colleagues demonstrated self-organized and polarized cortical tissues derived from directed differentiation of either mouse or human ESCs using a 3D aggregation culture protocol called SFEBq (serum-free culture of embryoid body-like quick aggregates) . The folThe isolation of hESCs and generation of hiPSCs, collectively known as hPSCs, have fueled the interest for advancing cellular regenerative therapies. Over the past two decades, robust protocols have been described for directed differentiation of hESCs and hiPSCs into different cell types in 2D monolayer cell culture systems. However, a 2D culture system has several limitations. First, this system fails to accurately mimic the natural structure of tissues or tumors, and thus is incapable of precisely recapitulating complex morphogenetic processes underlying embryonic development, cellular differentiation, tissue regeneration, and tumor formation. Moreover, the patterning, polarity, and mode of cell division are also altered in 2D culture, resulting in changes in gene expression and cell function .in vivo conditions. The organoid system has indeed been shown to be superior in several ways compared to 2D culture, because organoids have the ability to self-organize into remarkable tissue-like architecture and undergo multi-lineage differentiation containing heterogeneous populations of cells. The 3D organoid culture system also enables fundamental processes such as cellular migration and segregation, spatially restricted lineage commitment, and cellular organization to occur in a more physiologically relevant microenvironment. With the tractability and scalability in culturing methods, there has been significant progress in the generation of 3D organoids in vitro from hPSCs using knowledge gained over the years from many developmental biology studies in mouse and human.The search for a better model system has driven the development of 3D organoid culture for more accurate recapitulation of After the directed differentiation of hPSCs into defined germ layers—ectoderm, mesoderm, or endoderm—progenitors of diverse lineages representing a specific germ layer can arise in 3D aggregates to allow further differentiation into different tissues of interest. Such methods have led to the generation of a myriad of organoid types that model different tissues/organs derived from hPSCs including small intestine , colon , retina During development, the stomach epithelium forms invaginations into the lamina propria known as gastric units, which are subdivided into the pit and the gland . The matThe knowledge obtained from studies of anterior endoderm patterning and stomach development in animal models including the mouse has been instrumental in generating the first human gastric organoids through directed differentiation of hESCs as pioneered by the Wells laboratory ; Table 1in vivo mouse studies, they discovered that canonical Wnt signaling is required for fundus stomach specification. Thus, prolonged activation of Wnt signaling after the posterior foregut endoderm stage is able to produce fundus gastric organoids with different fundus-specific gastric cell types including chief cells, surface and neck mucous cells, and enteroendocrine cells  mice, the vasculature of hiPSC-derived liver bud organoids connected efficiently with host vessels forming a functional vasculature capable of inducing further functional maturation of hiPSC-derived hepatocytes. The hiPSC-derived liver organoids rescued and improved survival of the acute liver failure (ALF) mouse model. This co-culture method stresses the importance of multicellular interactions during liver development and provides a highly successful proof-of-principle approach likely applicable to other organ systems. Nonetheless, a major caveat of this study is that HUVECs and hMSCs are established cell lines that were not derived from the same hiPSCs, and without further modifications, this type of construct could trigger graft rejection upon transplantation.Early morphogenesis and specification of the formative liver bud depend highly on the interplay of signaling between hepatic endoderm cells with adjacent mesenchymal and endothelial progenitors . Based oTo overcome this major issue, An alternative approach reported by Steatohepatitis is a type of fatty liver disease characterized by inflammation of the liver with concurrent fat accumulation (steatosis). Based on the successful generation of intestinal organoids containing both endodermal and mesodermal lineages , Takebe’The liver is the target organ of many viruses including hepatitis B (HBV) and C (HCV). Evidence suggests that host genetic background might explain the heterogeneous outcome of these infections . Since rCholangiocytes are epithelial cells that form the adult biliary ductal system that regulates bile homeostasis and modulate inflammatory responses, as well as participates in repair of liver injuries. Several protocols have been reported for differentiating cholangiocytes from hPSCs; each used similar initial differentiation steps in order to generate hepatoblasts, and then used variations in order to specify and mature cholangiocytes , 2017. DWith successful generation of functionally mature cholangiocyte organoids, these platforms were used to model the pediatric biliary disorder Alagille syndrome, which is characterized by bile duct paucity caused by mutations in JAG1 or NOTCH2 . By bloccystic fibrosis transmembrane conductance regulator (CFTR) gene, which encodes a sodium chloride transporter. Loss or dysfunction of CFTR protein in cholangiocytes results in reduced intraluminal chloride secretion, increased bile viscosity, and biliary obstruction causing biliary fibrosis and cirrhosis   lesions both in vitro and in vivo. It is noteworthy that these PanIN organoids were not able to expand to form larger PanIN lesions or progress to the PDAC tumor stage upon in vivo transplantation into the mouse fat pad. It remains unknown how these organoids would behave if orthotopically transplanted in their natural environment. An interesting approach would be to generate hPSC-derived pancreatic organoids containing combinations of different driver mutations to model PDAC progression and metastasis.a (PDAC) . The halin vitro without a need for in vivo maturation  and stem cells, enteroendocrine cells, Paneth cells, and goblet cells. in vitro can largely recapitulate in vivo human intestinal development, allowing this system to be used for studying genetic diseases related to human intestinal development  gene is the main driver of colorectal cancer, found in ∼85% of cases. Recent advances in gene-editing technology coupled with protocols for hPSC-derived intestinal organoids have allowed modeling of colorectal cancer with individual driver mutations, with a particular focus on the initiation events of this disease. APC gene, in order to model FAP pathogenesis in vitro (Colorectal cancer is the second leading cause of cancer death worldwide. Mutation of the in vitro . The FAPin vitro ; Table 1in vitro, particularly for enteric viruses. Human intestinal organoids, derived from either hPSCs or adult stem cells, have recently been used to study the pathogenesis of some of the infectious pathogens that had been difficult to grow in 2D cell lines. The first report using hPSC-derived intestinal organoids to model viral gastrointestinal infections came from the Estes group (Gastrointestinal infections from bacteria, viruses, and parasites cause gastroenteritis leading to symptoms such as diarrhea, vomiting, and abdominal pain. The ability to fully understand how these pathogens interact with human intestinal cells in order to cause disease has been hampered by the inability to efficiently isolate, culture, and propagate the pathogens es group ; Table 1es group .Salmonella species are responsible for >90 million cases of gastroenteritis and 20 million cases of typhoid per year (Salmonella-related gastroenteritis but the disease and symptoms differ in mouse and human, prompting the need for a better model of this infection (Salmonella enterica serovar Typhimurium into the lumen of hPSC-intestinal organoids, Salmonella-containing vacuoles, and induce cytokine gene expression (in vitro, growing anaerobic bacteria in cell lines has been a challenge, since growing intestinal cells require oxygen. Clostridium difficle, an anaerobe and common cause of infectious nocosomial diarrhea, can survive up to 12 h when injected into the lumen of the hPSC-derived intestinal organoids, allowing the interaction of the bacteria with host epithelium to be studied. Upon infection, this bacterium caused disruption of intestinal epithelium, resulting in loss of paracellular barrier function, which is mainly mediated by toxin TcdA. These studies highlight the promise of this platform for understanding disease mechanisms causing other bacterial and protozoan-related gastroenteritis, both aerobic and anaerobic, which have not been previously investigated in other models. This platform could also be used to search for better treatments via drug screening to target pathogens, for which there are no efficient therapeutic agents.Enteric bacterial-related gastrointestinal infection, especially those caused by pathogenic per year . Mouse mnfection . By injepression . While iin vivo development, hPSC-derived organoids provide a unique model to study mechanisms underlying embryonic defects and diseases that are associated with these defects. Together with advances in gene-editing technology, targeted mutations or correction of mutated genes can be performed relatively efficiently at the hPSC level before differentiating into different lineages and at the organoid level prior to autologous transplantation.We have highlighted some of the advantages of using the endodermal organoid platform for modeling development and disease. Here, we briefly summarize the overall advantages of this system. Clearly, hPSC-derived endodermal organoids offer several significant advantages over 2D culture systems in addressing various aspects of human gut developmental biology, including lineage fate specification and regional organ patterning. Since the hPSC-to-organoid differentiation process resembles to a large extent in vivo transplantation. Drug screening and validation of drug derivatives in animal models is not only costly but also carries uncertainty of efficacy due to fundamental differences in physiology between human and mouse models. The hPSC-derived organoids thus offer a cost-efficient and reliable approach to overcome these limitations.Furthermore, a major advantage of this system is the unlimited supply of the starting materials from which these organoids can be generated due to the ability of hPSCs to self-renew and differentiate. This subsequently allows large-scale organoid production for various assays, including drug screening and in vivo engraftment of organoids is highly enhanced by the presence of mesenchymal cells (The hPSC-organoid system is not without its limitations. While some of the described hPSC-organoid models co-develop the supporting mesenchyme during the differentiation process, the system still generally lacks several stromal components such as the vasculature, neurons, and lymphatic and immune cells that preclude it from modeling diseases in which these stromal components play an important role in disease development. In addition, al cells  or co-cual cells . Thus, ial cells .in vivo engraftment to achieve maturation of organoids (in vitro by co-culturing with Jurkat T cells (Most studies rely upon rganoids . Based o T cells . Interlein vitro. There are several drawbacks associated with using these ECM components. First, they are produced by animal cell lines, which precludes their use for any application in human clinical trial studies. In addition, there is batch-to-batch variation in growth factors and ECM concentration during manufacturing, particularly in the production of Matrigel. Although growth factor-reduced versions of Matrigel are available, the ill-defined ECM concentrations could also affect the stiffness and porosity of the polymerized Matrigel. This could lead to lack of consistency in organoid differentiation, since stem and progenitor cell formation and differentiation of various cell types require different stiffness of ECM support (Matrigel and type I collagen are two commonly used ECM components used to support the growth of 3D organoid cultures  support . Further support . Thus, aThe possibility of generating human organoid cultures that resemble specific endoderm-derived organs has opened up enormous possibilities for using organoids not only for disease modeling but as a source for cell replacement therapies or even whole organ transplantation. In the next 5‒10 years, we envision much more insight into the influence of various stromal cell types on the expansion and maturation of hPSC-derived organoids. Culturing of different stromal cell types often requires ECM composition and stiffness that are different for optimum organoid growth. Thus, finding an optimal condition for co-culturing these cell types with organoids will be challenging. More studies focusing on integrating bioengineering technology with hPSC-derived organoids might promote the discovery of such ideal co-culturing conditions. This will require the development of improved synthetic ECM, in which the mechanical features such as stiffness can be spatially and temporally modulated. A few of these regulatable synthetic ECMs have been used to study cell migration . This inin vitro would dramatically move the field toward whole organ transplantation. The ability to generate a native cell-free tissue scaffold that could support partial or even whole organ growth in vivo platform for precise engraftment that can faithfully model organ development as well as disease pathogenesis and progression. Currently, most maturation and assessment of hPSC-derived organoid function and mutant phenotype are done by in vivo transplantation into immune-deficient NSG mice, which lack a competent immune environment. This limits the use of these models to explore the interaction of epithelial cells with the immune system in certain inflammatory diseases. The recent development of humanized mouse models can overcome this limitation allowing the pathology of these diseases to be modelled more accurately. A humanized mouse model is an immune-deficient mouse engrafted with human hematopoietic stem cells that can give rise to a variety of human immune cells throughout the life of the animal (in vivo setting without putting patients at risk. In the future, the tandem use of this platform with hPSC-derived organoid technology will provide a more rigorous and holistic approach for modeling numerous types of complex human diseases such as inflammatory bowel disease, infectious diseases, and various cancers.Another area needing attention is the development of an improved e animal . Due to in vivo lineage-tracing upon engraftment or for isolation of specific cell types after in vivo transplantation for downstream analysis.Advances in genome-editing technologies such as CRISPR-Cas9 open up possibilities for performing gene correction or studying specific mutations in development and disease. Gene editing in hPSC-derived organoids can already be applied to determine whether patient-specific mutations are pathogenic and to test potential novel therapies for precision medicine. Many challenges remain before gene-edited hPSC-derived organoids can be engrafted into humans for treating diseases; these include the relatively low efficiency of single-base gene editing and off-target effects caused by Cas9. With the establishment of efficient gene editing in organoids, editing in hPSC-derived organoids now can be performed at either of two stages, the pluripotent stem cell stage or the organoid stage, which allows stage-specific gene functions to be studied at both levels. In the near future, these technologies should be leveraged to generate inducible gene knockout or overexpression models that allow dissection of spatiotemporal impacts caused by specific mutations, particularly for genes that have multiphase functions. In addition, the development of additional cell type-specific reporters will facilitate monitoring the differentiation efficiency, for Conflict of interest: none declared.


Impulse control disorders (ICDs) in Parkinson's disease (PD) are aberrant behavior such as pathological gambling, hypersexuality, binge eating, and compulsive buying, which typically occur as a result of dopaminergic therapy. Numerous studies have focused on the broad spectrum of ICDs-related behaviors and their tremendous impact on patients and their family members. Recent advances have improved our understanding of ICDs. In this review, we discuss the epidemiology, pathogenesis and treatment of ICDs in the setting of PD. ChronicPG is defined as persistent and recurrent problematic gambling behavior as indicated by features such as increasing amounts of money, restlessness or irritability when cutting down, failing to control the behavior, preoccupation with gambling, lying to others, and so on (at least four criteria required). However, based on neuropsychiatric and possibly pathophysiological features, PG is currently considered as typical example of behavioral addiction and included in the diagnostic category of “substance-related and addictive disorders” according to DSM-5 , 7. HypeIn addition to the ICD, there are also some ICD-related disorders (ICRDs), such as Dopamine dysregulation syndrome (DDS) and punding. DDS implies repeated, unnecessary, or sometimes deleterious daily intake of dopaminergic agents far more than the dosage required for treatment of objective motor impairment, leading to severe dyskinesia, euphoria, aggressivity, hallucination, confusion, or frank psychosis . PundingBesides the classic ICDs symptoms there are many other ICDs-related behavioral problems including reckless driving , impulsiThis review mainly focuses on the ICDs in PD patients from the point of epidemiology, pathogenesis and therapeutic strategies.The prevalence of ICDs in PD patients using dopamine replacement therapy (DRT) varied from 3.5 to 43% –23. DopaICD is probably much more frequent in PD than previously reported as patients often underestimate the presence and severity of ICD symptoms . This ispost-hoc analysis about PD treated with rotigotine, although no definite conclusion can be reached on any dose-response relationship between rotigotine and ICDs, the incidence of ICDs appeared to increase with the dosage increase  (The duration of disease or medicine was correlated with ICDs in PD . Then th < 0.01) , remindiThere have been studies focusing on DNA polymorphisms of impulsive and compulsive behavior and additive behaviors in decades. A larger number of SNPs in dopaminergic  glutamatergic, serotonergic and opioid neurotransmitter system have been reported as candidates that improved predictability of ICDs when compared with clinical risk factors –56. We hA multicenter case-control study showed that specific subtypes of ICDs, such as compulsive shopping, binge eating and punding, had high frequency and were more severe in PD patients with Parkin mutation compared with non-Parkin mutation . The posComparing with single genetic variants, multiple gene interactions may play a more important role. Using candidate genetic multivariable pane, Kraemmer et al. conducted an interesting study to estimate ICD heritability in PD patients, which included several transmitter systems such as dopamine, serotonin, and norepinephrine genes. They found a substantial 11–16% increase in ICD behavior predictability compared to examining clinical variables alone. In addition, in 13 candidate variants, OPRK1, HTR2A and DDC genotypes were the strongest genetic predictive factors and OPRK1 polymorphism rs702764 significantly predicted incident of ICD behavior. Hence, they suggested the potential for developing clinical-genetic models to identify PD patients at increased risk of developing ICD and further guide treatments .Although polymorphisms of dopaminergic genes are not considered as the strongest risk factor for developing ICDs in PD patients at present, further research in the genetic susceptibility will explain the reason why some patients taking low doses of dopaminergic drugs still develop ICDs. Genetic studies can enlarge the understanding of ICDs from pathogenesis to therapy.Various neuropsychological studies have found that ICDs are associated with frontal/executive dysfunctions –70. ImbaHowever, there were several studies considering no difference in frontal executive dysfunction on neuropsychological testing between ICDs and non-ICDs patients in PD –78, whicIntertemporal choices, decisions between options available at different times, are commonly applied in impulsivity-related studies. The presence of impulsivity trait in intertemporal choices is usually suggested by a strong preference for small immediate rewards over large delayed ones . TemporaThe mechanism of ICDs is not well-understood. Yet based on animal and clinical researches, the dopaminergic system has been strongly implicated. There are three main dopaminergic pathways in central nervous systems (CNS): (a)the nigrostriatal pathway consisting of cell bodies in the substantia nigra (SN) whose axons terminate in the corpus striatum; (b) the mesocorticolimbic pathway , whose cell bodies are situated in the ventral tegmental area and whose axons project to parts of the limbic system; and (c) the tuberoinfundibular pathway, whose cell bodies are found in the ventral hypothalamus and project to the median eminence and pituitary gland . Of the Dopamine, as a modulator of risk behavior along the mesocorticolimbic pathway, plays an important role in reinforcement of learning. It signals the difference between predicted and experienced reward, and is also involved in shaping behavior to maximize reward and avoid punishment . NormallThere are several observations relevant to reward system and ICDs that are worth highlighting. First, the usual pleasurable stimuli such as food can induce tonic dopamine response in the outer shell of the nucleus accumbens. Second, dopamine auto-receptors in SN provide feedback to regulate synaptic dopamine concentration. Third, the orbitofrontal and anterior cingulate cortices (ACC) are involved in the top-down control, evaluating the reward and directing a suitable reaction, thus making adjustments for optimizing future choices . FinallyPD is associated with a neurodegenerative process that involves mesocorticolimbic network, but there is paucity of data linking abnormalities of this network to ICDs. One study, using volumetric magnetic resonance imaging (MRI) technique, found that amygdala volume was greater in PD patients with ICDs than those without ICDs, but similar to health control subjects . Since aThe mesocorticolimbic reward system plays an important role in the development and maintenance of addictive behavior. The reason for male preponderance in patients exhibiting this behavior is still unclear, but some imaging studies have suggested that males have a stronger functional connectivity in the reward mesocorticolimbic system than females , 92. ThuIn addition to the reward system, ICDs are also involved in the inhibition system. One fMRI study showed impairment in response-inhibition abilities in ICDs patients . The obsDopamine agonists improve motor symptoms in PD patients through their effects on the dorsal striatum, but they also activate the ventral striatum and the mesolimbic pathway . The braIn ICDs patients with PD, caregivers suffer huge burden from mental stress specifically on spousal safety. ICDs are associated with high rate of separation and divorce, child abuse, and neglect , 105. ItAs discussed above, ICDs are considered to have strong relationship with dopamine agonists. Decreasing or even withdrawing dopamine agonists is usually the first choice for clinicians. For PD patients who have developed ICDs on account of dopamine agonist treatment, they will get remission significantly after decreasing dosages. One longitudinal study suggested that ICDs resolved after 1 year in about 50% of the patients who stopped dopamine agonists and continued to improve . PatientConsidering the benefit from reducing dose of dopamine agonists such as pramipexole or ropinirole, it is recommended that temporary replacement of pramipexole by bromocriptine instead may relieve or reverse the ICDs while the D2 stimulation needed for motor symptoms are still maintained .Subthalamic nucleus (STN) deep brain stimulation (DBS) as a treatment for ICDs is considered a controversial method according to reported literature. Compared to patients without ICDs, ICDs patients exhibited increased proportion of subthalamic neurons responsive to prospective reward and decreased proportion to prospective loss in STN but no in GPi . STN-DBSAmantadine, acting as a dopaminergic and glutamatergic modulator, was reported to have great effect on reversing ICD symptoms without aggravating motor function. Amantadine add-on therapy is considered to reduce hypersensitivity in ICDs patients therefore decrease risky choice –127. HowAs ICDs are thought to be linked to oral dopamine agonists, strategies utilizing intrajejunal levodopa which utilize continuous drug delivery may decrease the risk of developing ICDs. This therapy may become a popular treatment of ICDs not only because its positive effect on behavioral disorders but also motor complications , 130.Clozapine were reported as a potential treatment for refractory ICDs. Clozapine not only has an effect on dopamine-blocking activity in the limbic system but also has weak antagonistic D3 and high antagonistic D4 activity that makes it capable of adjusting the reward circuit. Besides, N-desmethyloclozapine, the major active plasma metabolite of clozapine, may have an important partial agonist activity on dopamine D2/D3 receptors . There hThere has been an emerging method to treat ICDs using transcranial magnetic stimulation (TMS). A study reported that low-frequency repetitive TMS was used to treat four PD patients with punding whose symptoms were reversed magically. TMS deserves more studies to explore the best pattern and more indications .To date, there have been few studies concerning the role of cognitive behavior therapy in ICDs. Okai et al. proved the efficacy of cognitive behavior treatment in ICD patients with PD through a randomized controlled trail. They found the combined treatment of cognitive behavior treatment with medical care was more effective in reducing the severity of ICDs compared with medical care alone. The severity of symptom  index) significantly reduced 75% of the experimental group compared with only 29% in the control group. The intervention seemed to be also effective in depression and anxiety. Larger and long-term follow up studies are needed to confirm the benefit of cognitive behavior treatment in each subtype of ICDs, and meanwhile assess the cost-effectiveness .In addition to those treatments discussed above, valproate, zonisamide, naloxone, apomorphine, and bromocriptine may also be beneficial in treating ICDs , 137. DoIn conclusion, present studies remind us to pay much attention to non-motor symptoms including ICDs. With rapid advance regarding to ICDs, mechanisms of ICDs will become gradually clear and specific individual treatment strategies will be applied in the future. Given that ICDs would have terrible impact and consequence on families, patients and their caregivers should be educated in clinical practice. In addition, ICDs in PD patients may also provide a model for better understanding of the neurobiology of addiction.Y-CW provided the funding support and designed the project. J-FZ, X-XW, and YF searched for literature and wrote the manuscript. Y-CW, RF, and JJ revised the paper. All authors contributed to the article and approved the submitted version.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.


Imaging is integral in the diagnosis of canine intervertebral disc disease (IVDD) and in differentiating subtypes of intervertebral disc herniation (IVDH). These include intervertebral disc extrusion (IVDE), intervertebral disc protrusion (IVDP) and more recently recognized forms such as acute non-compressive nucleus pulposus extrusion (ANNPE), hydrated nucleus pulposus extrusion (HNPE), and intradural/intramedullary intervertebral disc extrusion (IIVDE). Many imaging techniques have been described in dogs with roles for survey radiographs, myelography, computed tomography (CT), and magnetic resonance imaging (MRI). Given how common IVDH is in dogs, a thorough understanding of the indications and limitations for each imaging modality to aid in diagnosis, treatment planning and prognosis is essential to successful case management. While radiographs can provide useful information, especially for identifying intervertebral disc degeneration or calcification, there are notable limitations. Myelography addresses some of the constraints of survey radiographs but has largely been supplanted by cross-sectional imaging. Computed tomography with or without myelography and MRI is currently utilized most widely and have become the focus of most contemporary studies on this subject. Novel advanced imaging applications are being explored in dogs but are not yet routinely performed in clinical patients. The following review will provide a comprehensive overview on common imaging modalities reported to aid in the diagnosis of IVDH including IVDE, IVDP, ANNPE, HNPE, and IIVDE. The review focuses primarily on canine IVDH due to its frequency and vast literature as opposed to feline IVDH. Intervertebral disc disease (IVDD) is the most common spinal cord disease of dogs, being responsible for 2.3–3.7% of admissions to veterinary hospitals , 2. The Even though IVDD was first reported in a paraplegic Dachshund by Dexler in 1896, it was truly well-characterized by Olsson and Hansen in the early 1950s . In 1952The most commonly described clinical form of intervertebral disc herniation (IVDH) is IVDE, which leads to acute spinal pain and variable degrees of paresis up to paralysis. Radiography was the most widely used method for the diagnosis of IVDD starting in the 1950s and extending until the 1980s , 9–11.Myelography started to be used in the 1960s and 1970s , 13, butA 2016 study looked at the practice patterns of diplomates of the American College of Veterinary Internal Medicine in the specialty of Neurology and American College of Veterinary Surgeons for the diagnosis of IVDH in North America. Among the board-certified neurologists, MRI was the most commonly used technique (75%), whereas among the board-certified surgeons, CT with or without concurrent myelography was the most commonly used imaging modality (58%). Approximately 28% of board-certified surgeons used MRI. Myelography alone was chosen as the most commonly used modality by 14% of board-certified surgeons, and <1% of board-certified neurologists . The imaAs the saying goes “the best treatment is a correct diagnosis,” in order to accurately diagnose all forms of IVDD and institute appropriate treatment, correct identification of affected disc sites, extension and lateralization are crucial for treatment planning. In this manuscript, we will review all imaging modalities used to presumptively or accurately diagnose all forms of IVDD.Hansen type I intervertebral disc extrusion (IVDE) is characterized by chondroid degeneration of the gelatinous nucleus pulposus with transformation to hyaline cartilage and mineralization. Ultimately this process leads to rupture of the annulus fibrosus and herniation of calcified nucleus pulposus into the vertebral canal and/or intervertebral foramen , 20. DisOrthogonal radiographic projections, lateral and ventrodorsal, are routinely used in the diagnostic investigation of cases suspected of IVDE. The use of general anesthesia has been recommended in order to obtain diagnostic radiographs . Howeverin situ, is a controversial one. Intervertebral disc mineralization is supportive of intervertebral disc degeneration but not disc extrusion. Radiographic detection of calcification requires significant IVD mineralization to be present, since many discs documented to have mineralization on histopathology were not apparent radiographically  thinning and deviation of the contrast columns, (2) thinning of the contrast columns is mild to severe or contrast columns are discontinuous, (3) thinning of the contrast columns is diffuse and beyond the boundaries of the affected disc, and (4) asymmetrical distribution of contrast column thinning cranial or caudal to the affected disc  46). It. It46). Estimates of diagnostic accuracy of myelography for the diagnosis and site of IVDE have ranged from 72 to 99% , 52, 53.Myelography is an invasive procedure and is associated with some inherent risks, primarily temporary deterioration of neurologic status, and post-myelographic seizures , 56. EveWhile myelography has limitations and has largely been superseded by cross-sectional imaging, it remains a reasonable imaging option for diagnosing IVDE. Importantly, in a study of 107 dogs assessing the choice of myelography or MRI for diagnosis of IVDE, patient outcomes using myelography were not inferior compared to MRI .Computed tomography (CT) is a very important modality in the diagnostic work-up of dogs and cats suspected of having IVDD , 58, 59.There are 3 possible techniques to achieve a diagnosis of IVDE using CT: non-contrast CT, intravenous contrast CT (CT-angiography), and subarachnoid contrast CT (CT-myelography). CT-myelography requires ~25 to 50% of the volume of contrast medium compared to conventional myelography, and it is therefore much safer. In all of these CT modalities, transverse images can be reformatted into other imaging planes, primarily when using multidetector CTs which allow multiplanar reformatting in different spatial planes , 61, 62.Most investigations relating to IVDD have been dedicated to non-contrast CT. The normal intervertebral disc is of uniform soft tissue opacity in CT images, with no visible distinction between the nucleus pulposus and annulus fibrosus . The spiThe CT characteristics of acute IVDE include hyperattenuating material within the vertebral canal, loss of epidural fat, and distortion of the spinal cord . A case Several studies compared the sensitivity of non-contrast CT to myelography and/or CT-myelography for the identification of IVDE in the thoracolumbar spine. A large retrospective study evaluated non-contrast CT and myelography in 182 dogs of varying breeds . Both meA retrospective study suggested that CT-angiography was as diagnostic as CT-myelography in dogs with IVDE, with sensitivities of 97 and 94%, respectively . This fiA prospective study of 46 dogs with acute cervical and thoracolumbar myelopathies mimicking the diagnostic work-up of any acute spinal case, compared four modalities: non-contrast CT, CT-angiography, myelography, and CT-myelography, using as gold standard either surgery or necropsy . Almost A retrospective study of 555 dogs with thoracolumbar myelopathy investigated parameters that could be used to predict the need for additional imaging beyond non-contrast CT . The vasBased on all the available information, it is possible to conclude that non-contrast CT is as diagnostic as myelography for the localization of IVDE in chondrodystrophic dogs. It can be reliably used in the diagnostic investigation of cases suspected of having IVDD, primarily small breed, young dogs, emphasizing the point that case selection is key when electing a diagnostic work-up with non-contrast CT. The selection of non-contrast CT should also be undertaken with the acceptance that further imaging, either CT-myelography or MRI, might be required should no lesion or a lesion not matching the neurolocalization be identified , 70, 71.MRI is considered the gold standard for diagnostic imaging in IVDD in both humans and veterinary patients. Manipulation of the various imaging characteristics of tissues allows the multiple anatomical structures within the vertebral column to be distinguished, including the supporting ligamentous structures, synovial joints, bone marrow, nerve roots, spinal cord parenchyma, cerebrospinal fluid, epidural fat, and the layers of the IVD . Images There is substantial variation in MRI quality in veterinary practice with both low and high field MRIs available. Due to upfront and maintenance costs, low-field (0.2–0.4 T) units currently greatly outnumber high-field ones, primarily in private referral practices . While lAs the diagnostic quality and accuracy of MRI for the diagnosis of IVDD are dependent on several technical aspects, a brief overview of these factors is warranted. For a comprehensive review of technical aspects, the reader is referred to other sources –76.Patients are typically positioned in dorsal recumbency. It is extremely important to achieve a straight spinal alignment to allow comparison of multiple intervertebral sites on sagittal images. Sandbags and foam wedges are very useful for this purpose . The higThe sagittal plane is used initially to localize specific intervertebral regions to be investigated with transverse slices. The FOV of the sagittal plane in low field MRIs can be small, so determination of the affected intervertebral disc(s) level can be challenging in the thoracolumbar region without reliable cranial and caudal vertebral references. A strategy commonly used is the identification of celiac and mesenteric arteries. In one study the celiac artery and mesenteric arteries were ventral to the first lumbar vertebra in 71 and 97% of dogs, respectively . In anot* or fast field echo—FFE) are also routinely acquired  compared with 16% of dogs with IVDP , 111. Va*W GRE and a variable degree of contrast enhancement is seen in 45% of dogs. Paravertebral signal alterations are more commonly seen in disc extrusions caudal from L1 and in animals with a more severe neurological grade. Histopathology typically does not reveal specific abnormalities and the underlying pathomechanism might be related to ischemia, muscle spasm or denervation edema  vs. MRI (1.0 T systems) for the diagnosis of thoracolumbar IVDH, using surgery as the gold standard. The first study had 44 dogs and found that the sensitivity of MRI was 98.5%, compared with 88.6% for CT for identifying the site of IVDH . In anotWhile MRI has been reported to be more accurate than CT in discriminating IVDE from IVDP, this distinction can still be difficult based on MRI . In ordeMRI findings have been compared to actual surgical findings by assessing the cranio-caudal extent of extruded disc material using calipers intraoperatively . In two A recent prospective low-field MR study evaluated the agreement between surgeon's perception of spinal cord decompression and residual disc on postoperative MR images acquired immediately after surgery in most cases . In mostProgressive myelomalacia (PMM) is one of the worst complications seen in dogs with IVDE. It is reported to occur in ~10–17.5% of paraplegic dogs with absent pain perception , 124, anIn contrast to IVDE, the degenerative process in IVDP is much slower, with concurrent changes in the annulus fibrosus and nucleus pulposus. The annulus progressively loses its structural integrity, which allows the nucleus pulposus to move dorsally into the weakened annulus fibrosus. This will cause gradual protrusion of the dorsal annulus fibrosus into the vertebral canal, ultimately resulting in chronic progressive spinal cord compression. The pathophysiology, classification and clinical presentation of animals with IVDP is discussed in more detail in a companion article of this issue by Fenn et al.Although IVDP is a common spinal disorder , only a Similar to IVDE, spinal radiographs cannot be used to confirm a diagnosis of IVDP. Common radiographic abnormalities seen in dogs with IVDP include vertebral endplate sclerosis (67%), and spondylosis deformans (47%) with narrowing of the intervertebral disc space occurring less commonly (25%) . AlthougUntil two decades ago, myelography was probably the most commonly used imaging modality to diagnose spinal conditions in veterinary medicine . MyelogrAlthough CT is widely used to diagnose acute and chronic IVDE, there are no studies that have specifically focused on the use of CT to diagnose IVDP. The herniated material in IVDP is not mineralized and is therefore difficult to visualize on non-contrast CT. Spinal cord compression can further not be directly visualized on non-contrast CT and it is therefore likely that it cannot reliably be used to obtain a diagnosis of IVDP . AlthougMRI has become the imaging modality of choice for most spinal disorders in veterinary medicine . AlthougMidline instead of lateralized intervertebral disc herniation was associated with a diagnosis of IVDPPartial instead of complete loss of the hyperintense signal of the nucleus pulposus was associated with a diagnosis of IVDPThe presence of a single intervertebral disc herniation instead of multiple intervertebral disc herniations was associated with IVDEHerniated material dispersed beyond the boundaries of the intervertebral disc space was associated with a diagnosis of IVDE.In a later study by the same group, using these four criteria significantly improved diagnostic accuracy and interobserver agreement of MRI to differentiate thoracolumbar IVDD subtypes . It is cA common MRI finding in animals with chronic intervertebral disc herniations is focal T2W intraparenchymal intensity changes at the site of spinal cord compression . As prevIntervertebral disc protrusion can also be a prominent component of more complex and multifactorial neurological syndromes, such as degenerative lumbosacral stenosis and disc-associated cervical spondylomyelopathy , 143. AlSince MRI has become more widely available in veterinary medicine, additional types of IVDH have been recognized, which are characterized by sudden herniation of non-degenerative or minimally degenerative nucleus pulposus. The two most common types of extrusion of non-degenerative or minimally degenerative nucleus pulposus are acute non-compressive nucleus pulposus extrusion (ANNPE) and hydrated nucleus pulposus extrusion (HNPE) . AnotherAcute non-compressive nucleus pulposus extrusion is characterized by a sudden extrusion of non- or minimally degenerative nucleus pulposus without residual spinal cord compression. This condition has been reported with various terms over the years, namely Hansen Type III IVD herniation (even though Hansen did not report it), traumatic IVD extrusion, IVD explosion, missile discs, and high-velocity low-volume IVD extrusion. Affected animals typically present with a peracute onset of possibly strongly lateralized clinical signs, often during strenuous exercise or trauma. Severity of clinical signs should not progress after the initial 24 h and sustained spinal hyperesthesia should not be present.Survey radiographs can be normal or reveal a narrowed intervertebral disc space in animals with ANNPE. This radiographic finding is not specific and does not help differentiating ANNPE from other types of IVDH. Myelography can reveal a small focal extradural compressive lesion overlying an intervertebral disc space, with an adjacent intramedullary pattern caused by spinal cord swelling  149). A. A149). MRI is considered the imaging modality of choice for ANNPE. The following MRI characteristics have been proposed to make a presumptive diagnosis of ANNPE in dogs :Focal intramedullary, often well-demarcated, spinal cord T2W hyperintensity, which is typically isointense on T1W sequencesThe lesion is located over an intervertebral disc space and is often lateralizedThe nucleus pulposus has a homogenous T2W hyperintense signal and a reduced volume. This is associated with a narrowed intervertebral disc spaceThere is a small volume of extradural material dorsal to the affected intervertebral disc space, with minimal to no spinal cord compression. This can be associated with signal changes in the epidural space.Other less commonly observed MRI changes can include a cleft in the dorsal part of the annulus fibrosus. Mild local enhancement of the meninges or epidural material after IV administration of gadolinium-based contrast has been reported , though The clinical presentation of animals with ANNPE is almost identical to that of animals with ischemic myelopathy, which is most commonly caused by fibrocartilaginous embolic myelopathy. Differentiating between both conditions is important because there are indications that the long-term outcome, and especially the prevalence of fecal incontinence, might be different between dogs with ANNPE and ischemic myelopathy , 156. SiAbnormalities observed on MRI in dogs with ANNPE have also been associated with the functional outcome , 160. LaHydrated nucleus pulposus extrusion (HNPE) is characterized by sudden extrusion of minimally to non-degenerative nucleus pulposus. Well-hydrated, gelatinous, extradural material can be identified in the vertebral canal, which is associated with varying degrees of spinal cord compression . AlthougMagnetic resonance imaging is the diagnostic modality of choice and specific, almost pathognomonic, MRI abnormalities have been described  148). T. T148). A narrowed intervertebral disc space with a reduced volume of hyperintense nucleus pulposus Ventral, midline, extradural compressive material, which is homogenously hyperintense on T2W sequences and isointense in all sequences to normal, non-degenerative nucleus pulposus lying immediately dorsal to the affected intervertebral discThe extruded material can have a characteristic bilobed or “seagull appearance.” This typical shape is possibly explained by the location of the compressive material just ventral to the intact dorsal longitudinal ligament .A T2W hyperintense intraparenchymal lesion can be present in the overlying spinal cord and extruded nucleus pulposus can demonstrate a degree of contrast enhancement , 162.Similar to ANNPE, MRI findings have been linked to the likelihood of neurological recovery in dogs with HNPE. Although T2W hyperintense intraparenchymal lesions are present in less than half of dogs with HNPE , 164, thAlthough MRI is preferred, one study evaluated the usefulness of CT to diagnose cervical HNPE . Non-con*-weighted GRE images) extending from the intervertebral disc into the spinal cord parenchyma  is the least common type of herniation of nucleus pulposus. This type of disc extrusion is characterized by intradural or intramedullary extrusion of calcified and dehydrated or minimally degenerate and hydrated intervertebral disc material , 146. Threnchyma  (146). Mrenchyma .While conventional advanced imaging  are indispensable in the diagnosis of canine IVDH, there is a growing role for specialized applications of MRI including diffusion tensor imaging (DTI) in evaluating this population.Diffusion tensor imaging is a variation on diffusion weighted imaging that relies on the strength and direction of cellular diffusion of water molecules to create images –169. TheSpinal cord DTI is useful to quantify disruption of the normally highly anisotropic white matter tracts and can detect microstructural changes such as axonal damage, demyelination, Wallerian degeneration and loss of tissue architecture . In expeThe feasibility of spinal cord DTI has been established in neurologically normal dogs –189. HeaDiffusion tensor imaging has been reported in dogs with experimental injury and various naturally-occurring myelopathies , 190–196Diffusion tensor imaging has been explored in dogs as a potential non-invasive biomarker and prognostic indicator , 197. InIn spite of the potential advantages, DTI faces several technical and logistical considerations that generally impede widespread use in dogs with SCI. DTI also requires specialized software, technical expertise and extensive post-processing further limiting its utility in real-time, clinical decision making for dogs with acute IVDH. Standardizing and optimizing acquisition and processing protocols will be important in order for DTI to be incorporated into routine clinical use in SCI patients. Despite limitations, DTI is worthy of continued development to complement standard MRI studies in cases of acute and chronic IVDH in dogs.Other novel advanced imaging techniques have been evaluated in the spinal cord of people including magnetic resonance spectroscopy, magnetization transfer imaging, myelin water fraction imaging and functional MRI , 198–201This review outlined the available imaging modalities used in the diagnosis of all forms of IVDD including IVDE, IVDP, ANNPE, HNPE, and IIVDE. Radiographs remain a screening tool but have limitations, especially with regard to differentiating between IVDD subtypes and offering a definitive diagnosis. Myelography, CT, or MRI are all viable ways to diagnose IVDD, with CT and MRI largely having supplanted myelography in routine clinical practice. While there are pros and cons for both CT and MRI, patient selection is the most important factor when choosing the appropriate imaging modality to maximize the likelihood of achieving a definitive diagnosis. Non-contrast CT is a quick and economical choice that is highly likely to be successful in an acutely non-ambulatory, chondrodystrophic dog where there is high suspicion for IVDE, with CT-myelography required in selected cases. Magnetic resonance imaging is considered the gold standard imaging modality for acute and chronic spinal cases due to its ability to allow spinal cord visualization and the diagnosis of IVDE, IVDP, ANNPE, HNPE, or IIVDE. There are a growing number of studies of DTI in dogs with IVDD that offer a means to assess microstructural lesion characteristics and spinal cord integrity. It is likely that additional, novel spinal cord imaging techniques will be developed for application in dogs with IVDD. Overall, diagnostic imaging is indispensable in the diagnosis of IVDD and a keen knowledge of the advantages and limitations of the various imaging modalities is crucial to maximize the diagnostic information obtained.RC, SD, ML, and HV contributed to manuscript concept, preparation, and editing. The additional members of the CANSORT-SCI contributed to manuscript concept, editing, and review. All authors contributed to the article and approved the submitted version.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.


Saccharomyces cerevisiae Sup35p translation terminator causes the [PSI+] nonsense suppression phenotype. This fascinating biological model helped us shape our understanding of the mechanisms of formation, propagation and elimination of infectious protein aggregates. We discovered that Sup35p is exported via EV, both in its soluble and aggregated infectious states. We recently reported that high amounts of Sup35p prion particles are exported to the yeast periplasm via periplasmic vesicles (PV) in glucose-starved cells. EV and PV are different in terms of size and protein content, and their export is inversely regulated by glucose availability in the growth medium. We believe these are important observations that should make us revise our current view on the way yeast prions propagate. Hence, I propose several hypotheses as to the significance of these observations for the transmission of yeast prions. I also discuss how yeast could be used as a powerful tractable biological model to investigate the molecular mechanisms of vesicle-mediated export of pathological protein aggregates implicated in neurodegenerative diseases.Infectious proteins or prions are non-native conformations of proteins that are the causative agents of devastating neurodegenerative diseases in humans and heritable traits in filamentous fungi and yeasts. Prion proteins form highly ordered self-perpetuating fibrillar aggregates that traffic vertically and horizontally from cell to cell. The spreading of these infectious entities relies on different mechanisms, among which the extracellular vesicles (EV)-mediated traffic. The prion form of the yeast  Saccharomyces cerevisiae hosts many unrelated prion proteins that are at the origin of heritable phenotypic traits. Of particular importance, decades of investigations into the [PSI+] nonsense suppression phenotype, which originates from the prion form of the translation terminator Sup35p, allowed tremendous insights into the mechanisms of prion genesis, propagation and elimination. A common feature shared by all these prion proteins is their ability to assemble into structurally distinct and highly ordered self-replicating fibrils, most often of amyloid nature, that spread vertically or horizontally from cell to cell.“Proteinaceous infectious particles”, or prions, are transmissible conformational states of proteins described mostly in mammals, filamentous fungi and yeasts. Bacterial and plant prion-like proteins were also reported, suggesting this phenomenon is universal and widely conserved throughout evolution. The prototypic mammalian prion protein PrP is the cause of infectious diseases, such as scrapie in sheep, bovine spongiform encephalopathy (BSE) in cow, chronic wasting disease in deer and elk, as well as kuru and Creutzfeld-Jacob diseases in humans. Additionally, the prion-like behavior of proteins such as α-synuclein, Tau, amyloid-β or huntingtin is at the origin of devastating neurodegenerative diseases such as Alzheimer's, Parkinson's or Huntington's diseases. The yeast et al. (2020), Mol Microbiol. doi: 10.1111/mmi.14515). We showed significant differences between PV and EV in terms of size, protein cargo and regulation by glucose availability. However, Sup35p-containing EV and PV probably share a common subcellular origin, and packaging of prion particles within vesicles occurs in actively dividing cells. Using protein transformation assays, we showed that Sup35p prion particles retain their infectivity within EV and PV. Thus, vesicle-embedded prion particles constitute a suitable source of propagons.Yeast prions are faithfully transmitted to daughter cells and mating partners via cytosolic diffusible protein entities often referred to as ‘propagons', but these are still not documented at the molecular level. This prompted us to investigate the properties and molecular nature of propagons. We showed that the infectivity of Sup35p prion particles changes dramatically during growth, depending on the metabolic status of the cells. Importantly, we discovered that infectious Sup35p prion particles are packaged within small exosome-like vesicles (~30-100 nm in diameter) and exported in the extracellular space. These extracellular vesicles (EV) are produced by virtually all living cells including cell-walled microorganisms such as yeasts and fungi. EV are thought to play important roles for intercellular communication by acting as vehicles for the transfer of nucleic acids, proteins, signaling molecules, sugars, lipids, and toxins or other pathogenic factors. EV mediate the clearance and contribute to the cell-to-cell transfer of prion-like protein aggregates associated with neurodegenerative diseases. Building upon this initial observation, we found that in glucose limiting conditions, surprisingly high amounts of Sup35p prion particles are exported into the periplasm via periplasmic vesicles (PV) . The cytoplasmic transmission of yeast prions during cell division is well established yet the precise molecular nature of propagons is unknown. It is also not clear whether the propagons are naked, coated with associated proteins or encapsulated into vesicles. Vesicle-embedded prion particles fulfill the essential features needed to qualify as propagons. First, they are able to faithfully seed homologous monomeric prions and induce the prion state. Secondly, their small size and mobility allow them to traffic efficiently across the bud neck and reach the daughter cell, in line with the high mitotic stability observed for most prion strains. Indeed, secretory vesicles significantly contribute to the growth of the yeast bud where they provide the macromolecules and enzymes required for building the newly forming plasma membrane and cell wall. Finally, propagons are shielded from the action of protein assemblies remodeling activities within the cell, such as molecular chaperones and proteolytic machineries. By hijacking the mother-to-bud vesicular traffic, prion particles could get around spatial quality control, a mechanism of asymmetric retention that protects daughter cells from aging damage accumulated by mother cells. Periplasmic vesicles, which could be reinternalized depending on growth conditions and the metabolic state of the cells, may also efficiently transmit prion particles to daughter cells while avoiding molecular crowding and ‘check-point' controls at the bud neck.It appears that a pool of infectious Sup35p prion particles ‘hidden' within vesicles is constituted in actively dividing cells, regardless of whether these vesicles are ultimately exported as EV or PV. We still need to address whether our findings apply to other yeast prions. In the meantime, we propose a working model for the propagation of yeast prions that takes into account their packaging within vesicles, which we believe plays a prominent role  which have been proposed to act as vehicles for their prion-like spreading pattern in neurodegenerative diseases. When heterologously expressed in yeast, human prion-like proteins and their variants bearing known familial mutations often retained their aggregation and cytotoxic properties. Furthermore, known modifiers of protein aggregation such as molecular chaperones or proteolytic systems are conserved in yeast and are able to act on these prion proteins. Yeast offers a vast array of fast and cost-effective experimental possibilities, including but not limited to the availability of genome-wide deletion and mutant libraries or automated high-throughput drug screening. While the isolation of EV from yeast culture supernatant is a cumbersome process poorly suited for screening purposes, the isolation of PV is on the contrary quick, easy and compatible with high-throughput assays. We predict that developing yeast models of vesicle-mediated prion proteins export will allow us not only to gain fundamental knowledge of the underlying mechanisms but also to design alternative strategies against the propagation of neuropathological protein assemblies.