Self-renewing Progenitor Cells Research Articles

MiR-6216 regulates neural stem cell proliferation by targeting RAB6B

Neural stem cells (NSCs) are a class of self-renewing, multipotent and undifferentiated progenitor cells that retain the capacity to both glial and neuronal lineages. MicroRNAs (miRNAs) are small non-coding RNAs that play an important role in stem cell fate determination and self-renewal. Our previous RNA-seq data indicated that the expression of miR-6216 was decreased in denervated hippocampal exosomes compared with normal. However, whether miR-6216 participates in regulating NSC function remains to be elucidated. In this study, we demonstrated that miR-6216 negatively regulates RAB6B expression. Forced overexpression of miR-6216 inhibited NSC proliferation, and overexpression of RAB6B promoted NSC proliferation. These findings suggest that miR-6216 played an important role in regulating NSC proliferation via targeting RAB6B, and improve the understanding of the miRNA-mRNA regulatory network that affects NSC proliferation.

An Update on Mesenchymal Stem Cell-Centered Therapies in Temporomandibular Joint Osteoarthritis.

Temporomandibular joint osteoarthritis (TMJOA) is a degenerative disease characterized by cartilage degeneration, disrupted subchondral bone remodeling, and synovitis, seriously affecting the quality of life of patients with chronic pain and functional disabilities. Current treatments for TMJOA are mainly symptomatic therapies without reliable long-term efficacy, due to the limited self-renewal capability of the condyle and the poorly elucidated pathogenesis of TMJOA. Recently, there has been increased interest in cellular therapies for osteoarthritis and TMJ regeneration. Mesenchymal stem cells (MSCs), self-renewing and multipotent progenitor cells, play a promising role in TMJOA treatment. Derived from a variety of tissues, MSCs exert therapeutic effects through diverse mechanisms, including chondrogenic differentiation; fibrocartilage regeneration; and trophic, immunomodulatory, and anti-inflammatory effects. Here, we provide an overview of the therapeutic roles of various tissue-specific MSCs in osteoarthritic TMJ or TMJ regenerative tissue engineering, with an additional focus on joint-resident stem cells and other cellular therapies, such as exosomes and adipose-derived stromal vascular fraction (SVF). Additionally, we summarized the updated pathogenesis of TMJOA to provide a better understanding of the pathological mechanisms of cellular therapies. Although limitations exist, MSC-centered therapies still provide novel, innovative approaches for TMJOA treatment.

Lipid Mediated Regulation of Adult Stem Cell Behavior.

Adult stem cells constitute an important reservoir of self-renewing progenitor cells and are crucial for maintaining tissue and organ homeostasis. The capacity of stem cells to self-renew or differentiate can be attributed to distinct metabolic states, and it is now becoming apparent that metabolism plays instructive roles in stem cell fate decisions. Lipids are an extremely vast class of biomolecules, with essential roles in energy homeostasis, membrane structure and signaling. Imbalances in lipid homeostasis can result in lipotoxicity, cell death and diseases, such as cardiovascular disease, insulin resistance and diabetes, autoimmune disorders and cancer. Therefore, understanding how lipid metabolism affects stem cell behavior offers promising perspectives for the development of novel approaches to control stem cell behavior either in vitro or in patients, by modulating lipid metabolic pathways pharmacologically or through diet. In this review, we will first address how recent progress in lipidomics has created new opportunities to uncover stem-cell specific lipidomes. In addition, genetic and/or pharmacological modulation of lipid metabolism have shown the involvement of specific pathways, such as fatty acid oxidation (FAO), in regulating adult stem cell behavior. We will describe and compare findings obtained in multiple stem cell models in order to provide an assessment on whether unique lipid metabolic pathways may commonly regulate stem cell behavior. We will then review characterized and potential molecular mechanisms through which lipids can affect stem cell-specific properties, including self-renewal, differentiation potential or interaction with the niche. Finally, we aim to summarize the current knowledge of how alterations in lipid homeostasis that occur as a consequence of changes in diet, aging or disease can impact stem cells and, consequently, tissue homeostasis and repair.

Single Cell Profiling of DNMT3A-Mutant Progenitors Reveals LY86 As a Novel Pre-Leukemia Marker and Potential Therapeutic Target

Acute Myeloid Leukemia (AML) is a clonal disease of the hematopoietic system that initiated and sustained by self-renewing hematopoietic stem and progenitor cells (HSPC). Mutations in the de novo DNA methyltransferase 3A (DNMT3A) gene occur in approximately 25% of adult acute myeloid leukemias (AML). Although the mechanisms through which such mutations promote leukemogenesis remain unclear, we have previously shown that loss of the DNMT3A can inhibit normal hematopoietic differentiation (Challen, Nature Genetics, 2011), accounting for the emergence of DNMT3A-HSC clones as a predisposition to hematological malignancies (Yang, Cancer Cell, 2015). Therapies that selectively eliminate the initiating pre-leukemic population would greatly improve outcomes for affected patients. However, the identification as well as selective elimination of such a distinct population has been problematic because of the considerable overlap in gene expression profiles with bulk normal hematopoietic stem cells. Molecular targets during leukemia development have not been well elucidated due to lack of the real definitive markers, which is a significant knowledge gap and barrier for understanding clonal leukemogenesis and therapeutic applications. Single-cell RNA sequencing has emerged as a powerful tool to analyze new cell types, cellular heterogeneity and cell differentiation routes. This technique made important contributions to our understanding of hematopoietic stem and cancer cell heterogeneity and selective resistance of cancer cell subpopulations to molecularly targeted cancer therapies. To identify early events involved in pre-leukemic transformation, we have performed single-cell RNA-sequencing (scRNA-seq) in WT and Dnmt3a KO mice. Flow cytometry sorted wild-type and pre-leukemic Dnmt3a KO HSPC cells were captured using 10X genomics chromium platform. After genome mapping, dimensional reduction, and clustering using Cell ranger pipeline, we generated transcriptome data and integrated the data sets using Seurat. Approximately 8,000 cells from each group were sequenced, and each cell expressed 1800-4500 genes. Graph-based clustering analysis revealed 16 unique cell clusters in both WT and DNMT3A KO mice. Interestingly, when compared with WT mice, we observed a 10-fold expansion of a single cell cluster in Dnmt3a KO cells before the advent of overt leukemia. This cluster co-expresses several stem cell genes including well-known leukemic stem cell surface markers such as CD47, as well as several novel genes. Some of these novel genes, encode cell surface proteins such as Ly6c2 and Ly86. We further validated protein expressions in AML cell lines and primary AML blast. In conclusion, the discovery of novel cluster in DNMT3A KO mice, and the relative abundance of this cluster in pre-leukemic stage of DNMT3A KO mice indicates that they promote leukemogenesis and offers an opportunity to specifically target DNMT3A mutant pre-leukemic cells using T cell immunotherapy. Disclosures No relevant conflicts of interest to declare.

Fli-1 Transcriptionally Integrates Microenvironmental Cues Sensing By Self-Renewing Hematopoietic Stem and Progenitor Cells

During adulthood and embryogenesis, fate decisions of hematopoietic stem and progenitor cells (HSPCs), such as specification, self-renewal, and differentiation are tightly regulated by their neighboring niche cells. Moreover, distinct types of niches supply differential cues to direct alternative cell fates for HSPCs. Yet, currently the intrinsic mechanisms balancing HSPC response obliqueness to microenvironmental signals are unknown. Friend Leukemia integration-1 (Fli-1), is an ETS transcription factor expressed by vascular beds and hematopoietic lineages. Fli-1 belongs to the "heptad factors" which are hypothesized to specify and sustain a hematopoietic cell fate. While Fli-1 overexpression is linked to leukemia, the functional role Fli-1 plays in HSPC specification and maintenance remains undefined. We show that inducible deletion of Fli-1 using a Rosa-CreERT2 transgenic adult mice (Fli-1ROSAΔ), results in a rapid thrombocytopenia-associated mortality. Transplantation of Fli-1ROSAΔ bone marrow (BM) cells into WT recipients, to exclude vascular-mediated defects, followed by induction of Fli-1 deletion, resulted with the same phenotype. In a set of modulated competitive transplantation experiments (differential induction time points pre- or post-transplant), we observed defective ability of Fli-1ROSAΔ HSPCs to lodge, engraft, and to sustain hematopoiesis post repopulation. Fli-1 deficient HSPCs exhibited reduced quiescent cell cycling status, a hallmark of stemness, and displayed enhanced apoptosis. Thus, Fli-1 is essential for previously unrecognized cell-autonomous HSPC functions. To determine whether Fli-1 modulates HSPC specification, Fli-1 was conditionally deleted using a developmental VE-cadherin (CDH5)-Cre transgenic model (Fli-1CDH5Δ). This resulted with premature mortality of Fli-1CDH5Δ embryos, accompanied with a hemorrhagic phenotype. Reduced numbers of hematopoietic cells were still detected in the AGM of e10.5 Fli-1CDH5Δ embryos. Conditional Fli-1 deletion using a developmental hematopoietic Vav-1 Cre transgenic model (Fli-1Vav-1Δ) resulted again with premature mortality. Reduced presence of embryonic Fli-1Vav-1Δ liver HSPCs was observed at e12.5. We also applied two in vitro co-culture systems, to study Fli-1 in endothelial to hematopoietic transition (EHT). First, isolated hemogenic endothelial cells (HEC) from WT and Fli-1ROSAΔ embryos were co-cultured with AGM-derived vascular niche. HECs isolated from Fli-1ROSAΔ AGM were still able to convert to CD45+ cells, however these cells did not expand on a vascular niche. Secondly, we have applied an endothelial to hematopoietic reprogramming system in which isolated lung ECs are virally introduced with DOX inducible FosB, Gfi1, Runx1, and Spi1 (FGRS) factors and co-cultured with vascular niche cells. Both WT and Fli-1ROSAΔ ECs were able to acquire a hemogenic like state resulting with a final capacity to convert into hematopoietic cells. Again, Fli-1ROSAΔ cells displayed lesser numbers of CD45+ cells at the end point, presumably due to impaired interaction with the vascular niche. Indeed, reduced expansion capacity was observed both for mature CD45+ and for HSPC derived from Fli-1CDH5Δ AGM region. Adult Fli-1ROSAΔ HSPCs exhibited the same niche-dependent expansion defect. Induction of Fli-1 deletion in vitro in adult HSPCs revealed loss of dependency on vascular niche inductive signals, as no additive expansion effect was observed for Fli-1ROSAΔ HSPCs in the presence of a vascular niche. Hence, Fli-1 is essential for HSPC expansion rather than hematopoietic specification. Differential RNA-seq analysis combined with epigenetic studies of expanding WT and Fli-1ROSAΔ HSPCs, revealed dysregulation of Fli-1-controlled pathways involved in transduction of microenvironmental signals for self-renewal. Unexpectedly, H3K27Ac analysis, a marker for transcriptional priming, revealed increased global acetylation of Fli-1ROSAΔ HSPCs' chromatin. Therefor, Fli-1 may not only perform as transcription activator, but foremostly as a genomic suppressor via modulation of histone acetylation status. Decrypting the mechanism(s) by which Fli-1 orchestrates HSPC self-renewal, may promote an improved expansion protocol of human HSPC pre-transplantation, and provide additional insights for microenvironmental sensing by Fli-1-dependent leukemic cells. Disclosures No relevant conflicts of interest to declare.

Tannic acid inhibits electrogenic Na+/HCO3- co-transporter activity in embryonic neural stem cell-derived radial glial-like cells.

Self-renewing neural stem cells and progenitor cells are cell populations that generate radial glial cells and neurons through asymmetric division. Regulation of intracellular pH in stem cells with high metabolic activity is critical for both cell signaling and proliferation. We have recently found that a S0859-inhibitable electrogenic Na+/HCO3− co-transporter (NBCe1, Slc4a4), is the primary pHi regulatory mechanism in stem cell-derived radial glial-like cells. Here we show, by using the voltage-sensitive fluorescent dye DiBAC4(3) and BCECF, a pH-sensitive dye, that an antioxidant, tannic acid (100 µM), can inhibit potassium- and calcium-dependent rapid changes in membrane potential and NBCe1 mediated pHi regulation in brain-derived glial-like cells in vitro. Furthermore, neural stem cell differentiation and neurosphere formation (proliferation) were completely inhibited by tannic acid. The present study provides evidence that tannic acid is a natural inhibitor of NBCe1. It is tempting to speculate that tannic acid or related compounds that inhibits NBCe1-mediated pHi regulation in glial-like cells may also have bearing on the treatment of glial neoplasms.

Single-cell transcriptome analysis reveals diverse islet-infiltrating T cell subsets and a role for BATF in promoting the diabetogenic activity of CD8 T cells

Abstract T cells infiltrate pancreatic islets and directly mediate the destruction of insulin-producing β cells during the development of type 1 diabetes (T1D). However, islet-infiltrating T cell differentiation states and functional diversity have not been completely defined. We used unbiased single-cell RNA sequencing analyses to define the phenotypic complexity of islet-infiltrating T cells in non-obese diabetic (NOD) mice. In the CD4 T cell compartment, we identified naïve, memory, and regulatory T cells, as well as multiple Il21 expressing effector subsets positive for markers indicative of Th1 and Tfh cells. In the CD8 T cell compartment, we identified naïve cells and two activated subsets defined by Slamf6 or Cxcr6 expression, respectively resembling the self-renewing progenitor cells and terminally differentiated effectors found during chronic lymphocytic choriomeningitis virus (LCMV) infection. Single-cell regulatory network inference and clustering (SCENIC) analysis revealed that regulon activity of several transcription factors with known roles in effector CD8 T cell function including Batf were turned on in the Slamf6+ and Cxcr6+ cells. Previous studies have shown that IL-21 induced BATF expression in CD8 T cells is critical to sustain their effector function against chronic LCMV infection. Similarly, we found lower BATF expression in activated islet CD8 T cells from NOD. Il21+/− compared to NOD mice. We further demonstrated that overexpression of BATF in β cell autoreactive CD8 T cells eliminated their need for IL-21 to cause T1D. Our results reveal phenotypically diverse and novel islet-infiltrating T cell subsets and suggest a model in which the IL-21-BATF pathway is critical for the diabetogenic activity of CD8 T cells.

Feedforward regulation of Myc coordinates lineage-specific with housekeeping gene expression during B cell progenitor cell differentiation.

The differentiation of self-renewing progenitor cells requires not only the regulation of lineage- and developmental stage–specific genes but also the coordinated adaptation of housekeeping functions from a metabolically active, proliferative state toward quiescence. How metabolic and cell-cycle states are coordinated with the regulation of cell type–specific genes is an important question, because dissociation between differentiation, cell cycle, and metabolic states is a hallmark of cancer. Here, we use a model system to systematically identify key transcriptional regulators of Ikaros-dependent B cell–progenitor differentiation. We find that the coordinated regulation of housekeeping functions and tissue-specific gene expression requires a feedforward circuit whereby Ikaros down-regulates the expression of Myc. Our findings show how coordination between differentiation and housekeeping states can be achieved by interconnected regulators. Similar principles likely coordinate differentiation and housekeeping functions during progenitor cell differentiation in other cell lineages.

Clonal derivation of white and brown adipocyte progenitor cell lines from human pluripotent stem cells

BackgroundThe role of brown fat in non-shivering thermogenesis and the discovery of brown fat depots in adult humans has made it the subject of intense research interest. A renewable source of brown adipocyte (BA) progenitors would be highly valuable for research and therapy. Directed differentiation of human pluripotent stem (hPS) cells to white or brown adipocytes is limited by lack of cell purity and scalability. Here we describe an alternative approach involving the identification of clonal self-renewing human embryonic progenitor (hEP) cell lines following partial hPS cell differentiation and selection of scalable clones.MethodsWe screened a diverse panel of hPS cell-derived clonal hEP cell lines for adipocyte markers following growth in adipocyte differentiation medium. The transcriptome of the human hES-derived clonal embryonic progenitor cell lines E3, C4ELS5.1, NP88, and NP110 representing three class of definitive adipocyte progenitors were compared to the relatively non-adipogenic line E85 and adult-derived BAT and SAT-derived cells using gene expression microarrays, RT-qPCR, metabolic analysis and immunocytochemistry. Differentiation conditions were optimized for maximal UCP1 expression.ResultsMany of the differentiated hEP cell lines expressed the adipocyte marker, FAPB4, but only a small subset expressed definitive adipocyte markers including brown adipocyte marker, UCP1. Class I cells (i.e., E3) expressed CITED1, ADIPOQ, and C19orf80 but little to no UCP1. Class II (i.e., C4ELS5.1) expressed CITED1 and UCP1 but little ADIPOQ and LIPASIN. Class III (i.e., NP88, NP110) expressed CITED1, ADIPOQ, C19orf80, and UCP1 in a similar manner as fetal BAT-derived (fBAT) cells. Differentiated NP88 and NP110 lines were closest to fBAT cells morphologically in adiponectin and uncoupling protein expression. But they were more metabolically active than fBAT cells, had higher levels of 3-hydroxybutyrate, and lacked expression of fetal/adult marker, COX7A1. The hEP BA progenitor lines were scalable to 17 passages without loss of differentiation capacity and could be readily rederived.ConclusionsTaken together, these data demonstrate that self-renewing adipocyte progenitor cells can be derived from hES cells and that they are functionally like BAT cells but with unique properties that might be advantageous for basic research and for development of cell-based treatments for metabolic diseases.

Tissue nonspecific alkaline phosphatase promotes calvarial progenitor cell cycle progression and cytokinesis via Erk1,2.

Bone growth is dependent upon the presence of self-renewing progenitor cell populations. While the contribution of Tissue Nonspecific Alkaline Phosphatase (TNAP) enzyme activity in promoting bone mineralization when expressed in differentiated bone forming cells is well understood, little is known regarding the role of TNAP in bone progenitor cells. We previously found diminished proliferation in the calvarial MC3T3E1 cell line upon suppression of TNAP by shRNA, and in calvarial cells and tissues of TNAP-/- mice. These findings indicate that TNAP promotes cell proliferation. Here we investigate how TNAP mediates this effect. Results show that TNAP is essential for calvarial progenitor cell cycle progression and cytokinesis, and that these effects are mediated by inorganic phosphate and Erk1/2. Levels of active Erk1/2 are significantly diminished in TNAP deficient cranial cells and tissues even in the presence of inorganic phosphate. Moreover, in the absence of TNAP, FGFR2 expression levels are high and FGF2 rescues phospho-Erk1/2 levels and cell cycle abnormalities to a significantly greater extent than inorganic phosphate. Based upon the data we propose a model in which TNAP stimulates Erk1/2 activity via both phosphate dependent and independent mechanisms to promote cell cycle progression and cytokinesis in calvarial bone progenitor cells. Concomitantly, TNAP feeds back to inhibit FGFR2 expression. These results identify a novel mechanism by which TNAP promotes calvarial progenitor cell renewal and indicate that converging pathways exist downstream of FGF signaling and TNAP activity to control craniofacial skeletal development.

Immune Checkpoints Acting as Gate-keepers of T Lymphocyte Self-renewal

Abstract Immune checkpoint inhibition represents a promising therapeutic modality for several previously incurable cancer syndromes. Why successful T cell responses are achieved in some patients but not others is incompletely understood. Because blockade of more than one inhibitory signal is now being investigated as approach to increase the chances of therapeutic success, we investigated how combined loss of PD-1 and LAG-3 signaling in CD8+ T cells would influence a well-characterized immune response. After challenge with Vaccinia virus, T cells from mice lacking both inhibitory pathways underwent a more vigorous primary effector cell response but were severely defective during a secondary challenge. During modeled T cell activation, immune checkpoint inhibition resulted in greater production of irreversibly differentiated effector cell progeny, but this came at the expense of accelerated depletion of self-renewing progenitor cells. Pharmacological interventions that impede anabolism-associated signaling were able to correct progenitor cells loss in the face of checkpoint inhibition. Unleashing greater and greater T cell activation may result in regenerative failure of critical clones. By fostering the expansion of self-renewing progenitors, reversible agents that dampen T cell signal strength might paradoxically improve durability of immune checkpoint inhibition.

Stem cells….Rejuvenate, Resuscitate, Revitalise the dead tooth - a review

Stem cells are defined as clonogenic self-renewing progenitor cells that can generate into one or more specialized cell types. Stem cells are biological cells found in all multi-cellular organisms that can divide through mitosis and differentiate into diverse specialized cell types and can self renew to produce more stem cells. Self renewal and totipotency are characteristic of stem cells. Though totipotency is shown by very early embryonic stem cells the adult stem cells possess multi-potency and differential plasticity which can be exploited for future generation of therapeutic options. Thus they represent an important building block for regenerative medicine and tissue engineering.Teeth are the most natural non-invasive source of stem cells. Dental stem cells which are easy convenient and affordable to collect hold promise for a range of very potential therapeutic applications. The search for more accessible mesenchymal stem cells MSCs than those found in bone marrow has propelled interest in dental tissues which are rich sources of stem cells. This article provides an overview of stems cells and then focuses on dental stem cells DSCs and how recent developments have the potential to greatly impact the way DSCs might be used in future regenerative medicine applications that include regenerative endodontic therapies.

Identification of gene expression signatures across different types of neural stem cells with the Monte-Carlo feature selection method.

Adult neural stem cells (NSCs) are a group of multi-potent, self-renewing progenitor cells that contribute to the generation of new neurons and oligodendrocytes. Three subtypes of NSCs can be isolated based on the stages of the NSC lineage, including quiescent neural stem cells (qNSCs), activated neural stem cells (aNSCs) and neural progenitor cells (NPCs). Although it is widely accepted that these three groups of NSCs play different roles in the development of the nervous system, their molecular signatures are poorly understood. In this study, we applied the Monte-Carlo Feature Selection (MCFS) method to identify the gene expression signatures, which can yield a Matthews correlation coefficient (MCC) value of 0.918 with a support vector machine evaluated by ten-fold cross-validation. In addition, some classification rules yielded by the MCFS program for distinguishing above three subtypes were reported. Our results not only demonstrate a high classification capacity and subtype-specific gene expression patterns but also quantitatively reflect the pattern of the gene expression levels across the NSC lineage, providing insight into deciphering the molecular basis of NSC differentiation.

Long-Term Culture of Self-Renewing Pancreatic Progenitor Cells Derived from Human Pluripotent Stem Cells

Long-Term Culture of Self-Renewing Pancreatic Progenitor Cells Derived from Human Pluripotent Stem Cells

Genetic Modulation Therapy Through Stem Cell Transplantation for Human Immunodeficiency Virus 1 Infection

Highly active anti-retroviral treatment has changed the dimensions of the outcomes for patients suffering from human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS). However, HIV infection is still an ailment which is spreading throughout the world extensively. Given the confinements of the present restorative methodologies and the non-availability of any strategic vaccination against HIV, there is a squeezing need to build a therapeutic treatment.Viral tropism for HIV includes CD4+ cells, macrophages, and microglial cells, and it is through binding with co-receptors C-C chemokine receptor type 5 (CCR5) and C-X-C chemokine receptor type 4 (CXCR4). While these cell types are present in all individuals, there are rare cases that stayed uninfected even after getting exposed to an overwhelming load of HIV. Research revealed a homozygous 32-base pair deletion (Δ32/Δ32) in CCR5. After careful consideration, a hypothesis was proposed a few years back that a cure for HIV disease is possible, through hematopoietic stem cells transplantation from a donor homozygous for the CCR5-Δ32 deletion.Hematopoietic stem cell (HSC) based quality treatment may serve as a promising tool as these perpetual, self-renewing progenitor cells could be modified to oppose HIV infection. If done properly, the changed HSCs would offer the permanent creation of genetically modified cells that are resistant to HIV infection and/or have improved hostility to viral action which will eventually clear the contaminated cells.The purpose of this review is to concentrate on two facets of HSC genetic treatment for potentially life-threatening HIV infection: building HIV-resistant cells and designing cells that can target HIV disease. These two strategic approaches can be the frontline of a quality treatment plan against HIV infection and, as an individual treatment or a combination thereof, has been proposed to possibly destroy HIV altogether.

MTORC1 signaling and primary cilia are required for brain ventricle morphogenesis

Radial glial cells (RCGs) are self-renewing progenitor cells that give rise to neurons and glia during embryonic development. Throughout neurogenesis, these cells contact the cerebral ventricles and bear a primary cilium. Although the role of the primary cilium in embryonic patterning has been studied, its role in brain ventricular morphogenesis is poorly characterized. Using conditional mutants, we show that the primary cilia of radial glia determine the size of the surface of their ventricular apical domain through regulation of the mTORC1 pathway. In cilium-less mutants, the orientation of the mitotic spindle in radial glia is also significantly perturbed and associated with an increased number of basal progenitors. The enlarged apical domain of RGCs leads to dilatation of the brain ventricles during late embryonic stages (ventriculomegaly), which initiates hydrocephalus during postnatal stages. These phenotypes can all be significantly rescued by treatment with the mTORC1 inhibitor rapamycin. These results suggest that primary cilia regulate ventricle morphogenesis by acting as a brake on the mTORC1 pathway. This opens new avenues for the diagnosis and treatment of hydrocephalus.

Overexpression of Glutamate Decarboxylase in Mesenchymal Stem Cells Enhances Their Immunosuppressive Properties and Increases GABA and Nitric Oxide Levels.

The neurotransmitter GABA has been recently identified as a potent immunosuppressive agent that targets both innate and adaptive immune systems and prevents disease progression of several autoimmunity models. Mesenchymal stem cells (MSCs) are self-renewing progenitor cells that differentiate into various cell types under specific conditions, including neurons. In addition, MSC possess strong immunosuppressive capabilities. Upon cytokine priming, undifferentiated MSC suppress T-cell proliferation via cell-to-cell contact mechanisms and the secretion of soluble factors like nitric oxide, prostaglandin E2 and IDO. Although MSC and MSC-derived neuron-like cells express some GABAergic markers in vitro, the role for GABAergic signaling in MSC-mediated immunosuppression remains completely unexplored. Here, we demonstrate that pro-inflammatory cytokines selectively regulate GAD-67 expression in murine bone marrow-MSC. However, expression of GAD-65 is required for maximal GABA release by MSC. Gain of function experiments using GAD-67 and GAD-65 co-expression demonstrates that GAD increases immunosuppressive function in the absence of pro-inflammatory licensing. Moreover, GAD expression in MSC evokes an increase in both GABA and NO levels in the supernatants of co-cultured MSC with activated splenocytes. Notably, the increase in NO levels by GAD expression was not observed in cultures of isolated MSC expressing GAD, suggesting crosstalk between these two pathways in the setting of immunosuppression. These results indicate that GAD expression increases MSC-mediated immunosuppression via secretion of immunosuppressive agents. Our findings may help reconsider GABAergic activation in MSC for immunological disorders.

Cell-cycle-independent transitions in temporal identity of mammalian neural progenitor cells.

During cerebral development, many types of neurons are sequentially generated by self-renewing progenitor cells called apical progenitors (APs). Temporal changes in AP identity are thought to be responsible for neuronal diversity; however, the mechanisms underlying such changes remain largely unknown. Here we perform single-cell transcriptome analysis of individual progenitors at different developmental stages, and identify a subset of genes whose expression changes over time but is independent of differentiation status. Surprisingly, the pattern of changes in the expression of such temporal-axis genes in APs is unaffected by cell-cycle arrest. Consistent with this, transient cell-cycle arrest of APs in vivo does not prevent descendant neurons from acquiring their correct laminar fates. Analysis of cultured APs reveals that transitions in AP gene expression are driven by both cell-intrinsic and -extrinsic mechanisms. These results suggest that the timing mechanisms controlling AP temporal identity function independently of cell-cycle progression and Notch activation mode.

A novel lineage restricted, pericyte-like cell line isolated from human embryonic stem cells.

Pericytes (PCs) are endothelium-associated cells that play an important role in normal vascular function and maintenance. We developed a method comparable to GMP quality protocols for deriving self-renewing perivascular progenitors from the human embryonic stem cell (hESC), line ESI-017. We identified a highly scalable, perivascular progenitor cell line that we termed PC-A, which expressed surface markers common to mesenchymal stromal cells. PC-A cells were not osteogenic or adipogenic under standard differentiation conditions and showed minimal angiogenic support function in vitro. PC-A cells were capable of further differentiation to perivascular progenitors with limited differentiation capacity, having osteogenic potential (PC-O) or angiogenic support function (PC-M), while lacking adipogenic potential. Importantly, PC-M cells expressed surface markers associated with pericytes. Moreover, PC-M cells had pericyte-like functionality being capable of co-localizing with human umbilical vein endothelial cells (HUVECs) and enhancing tube stability up to 6 days in vitro. We have thus identified a self-renewing perivascular progenitor cell line that lacks osteogenic, adipogenic and angiogenic potential but is capable of differentiation toward progenitor cell lines with either osteogenic potential or pericyte-like angiogenic function. The hESC-derived perivascular progenitors described here have potential applications in vascular research, drug development and cell therapy.

Isolation and Functional Characterization of Equine Adipos Tissue Derived Mesenchymal Stem Cells

Abstract Mesenchymal stem cells (MSCs) isolated from different sources are self-renewing progenitor cells with multipotent differentiation capacity. MSCs posed the capacity to proliferate extensively in vitro in optimal culture conditions, and represents the key factors in regenerative medicine. Our objective was to isolate and characterize equine MSCs from adipose tissue. Samples were obtained during castration. The adipose tissue samples were enzymatically digested and the isolated cells were cultured in DMEM/F12 medium. MSCs were characterized by morphology, multilineage differentiation capacity and expression of specific markers. Equine adipose tissue derived stem cells displayed mostly fibroblastic–like morphology, capable of trilineage diffentiation capacity and showed significant expression of CD105, CD44, CD90, CD49 while were negative for CD43 and CD73. This study demonstrated the characteristics of equine adipose tissue derived stem cells, ideal candidate for veterinary regenerative medicine .