Project description:We engineered a novel human iPSC-derived organoid system enriched with mature, myelinating oligodendrocytes and functionally reactive microglia. This model enables the study of human CNS remyelination following a demyelinating insult, encapsulating: myelin fragmentation, microglial clearance of myelin debris and oligodendrocyte genesis, differentiation, and axon ensheathment. This system provides a powerful and unparalleled capacity to interrogate complex human cell behaviour, relevant to those studying glial biology and neurological disease mechanisms.
Project description:Transcriptomic profiles of 6 commercially-available human patient-derived gastrointestinal organoid lines were obtained and compared to transcriptomic profile of a commercially available human iPSC-induced colon organoid line. Transcriptomic profile of iPSC-derived human colon organoid line was compared after culture in either Corning growth-factor-reduced Matrigel (Corning 356231) or MilliporeSigma growth-factor-reduced ECMGel (E6909)
Project description:Failure of oligodendrocytes to remyelinate underlies diseases such as multiple sclerosis (MS). We found that epigenetic silencing prevents oligodendrocytes from producing myelin sheaths in demyelinating MS lesions. Here, we developed a transgenic reporter system to identify a small-molecule epigenetic modulator that stimulates oligodendrocyte maturation and myelin ensheathment in vitro. This compound promoted remyelination in animal models of MS and myelination of regenerated axons and increased myelin sheath lengths in human iPSC-derived organoids. Multi-omics analyses revealed that the compound induced an enhancer/super-enhancer landscape that upregulates crucial myelinogenesis-associated pathways, including RRAS2-AKT signaling, driving actin depolymerization necessary for myelin ensheathment. Strikingly, the compound also induced phase-separated nuclear condensates of SREBP1/2, which concentrate transcriptional co-activators to drive lipid and cholesterol biosynthesis. Silencing expression of a potential target of the small molecule, HDAC3, facilitated robust myelination and remyelination. Our findings suggest that small-molecule-modulated epigenome rejuvenation relieves epigenetic silencing barriers and promotes myelin repair.
Project description:Failure of oligodendrocytes to remyelinate underlies diseases such as multiple sclerosis (MS). We found that epigenetic silencing prevents oligodendrocytes from producing myelin sheaths in demyelinating MS lesions. Here, we developed a transgenic reporter system to identify a small-molecule epigenetic modulator that stimulates oligodendrocyte maturation and myelin ensheathment in vitro. This compound promoted remyelination in animal models of MS and myelination of regenerated axons and increased myelin sheath lengths in human iPSC-derived organoids. Multi-omics analyses revealed that the compound induced an enhancer/super-enhancer landscape that upregulates crucial myelinogenesis-associated pathways, including RRAS2-AKT signaling, driving actin depolymerization necessary for myelin ensheathment. Strikingly, the compound also induced phase-separated nuclear condensates of SREBP1/2, which concentrate transcriptional co-activators to drive lipid and cholesterol biosynthesis. Silencing expression of a potential target of the small molecule, HDAC3, facilitated robust myelination and remyelination. Our findings suggest that small-molecule-modulated epigenome rejuvenation relieves epigenetic silencing barriers and promotes myelin repair.
Project description:Failure of oligodendrocytes to remyelinate underlies diseases such as multiple sclerosis (MS). We found that epigenetic silencing prevents oligodendrocytes from producing myelin sheaths in demyelinating MS lesions. Here, we developed a transgenic reporter system to identify a small-molecule epigenetic modulator that stimulates oligodendrocyte maturation and myelin ensheathment in vitro. This compound promoted remyelination in animal models of MS and myelination of regenerated axons and increased myelin sheath lengths in human iPSC-derived organoids. Multi-omics analyses revealed that the compound induced an enhancer/super-enhancer landscape that upregulates crucial myelinogenesis-associated pathways, including RRAS2-AKT signaling, driving actin depolymerization necessary for myelin ensheathment. Strikingly, the compound also induced phase-separated nuclear condensates of SREBP1/2, which concentrate transcriptional co-activators to drive lipid and cholesterol biosynthesis. Silencing expression of a potential target of the small molecule, HDAC3, facilitated robust myelination and remyelination. Our findings suggest that small-molecule-modulated epigenome rejuvenation relieves epigenetic silencing barriers and promotes myelin repair.
Project description:Understanding the regulation of oligodendrocyte development and myelination in the central nervous system (CNS) is essential, not only to facilitate myelin repair but also to define the role of oligodendrocytes in maintaining axonal integrity. In vitro studies have implicated astrocytes in influencing multiple aspects of oligodendrocytes and their precursors, however the in vivo role of astrocytes in myelination and myelin repair remain poorly defined. We show that astrocyte ablation during postnatal spinal cord development resulted in a concomitant delay in myelination, demonstrating a critical role for astrocytes in promoting developmental myelination. By contrast, in the adult CNS, localized ablation of astrocytes 2 days after a demyelinating insult resulted in increased numbers of oligodendrocytes and accelerated remyelination in both the spinal cord and the corpus callosum. Microarray analysis reveals astrocytic NF-kB signaling pathway as a major contributor to pathological events occurring after demyelination. We suggest that the localized functions of astrocytes are fundamentally different during developmental myelination and myelin repair. Astrocytes are critical for developmental myelination, however in a demyelinating environment they are detrimental to myelin repair.
Project description:Human induced pluripotent stem cell (hiPSC)-derived cardiovascular cells are promising cell source for cell therapy to repair the heart. Cardiac microtissue consisted of cardiomyocytes and fibroblast cells exhibited much better physiological functions. How different cardiovascular cell types interact and evolve in 3D microenvironment is unknown. In this study, we performed single-cell transcriptome profiling of hiPSC-derived mini-cardiac organoid consisted of cardiomyocytes, endothelial cells and smooth muscle cells. Our analysis showed that cardiac fibroblasts emerged spontaneously in 3D microenvironment which in turn facilitated the maturation of cardiomyocytes. HiPSC-derived cardiomyocytes, endothelial cells and smooth muscle cells assembled into mini-cardiac organoid in collagen-matrigel after 2 weeks. Single-cell study uncovered significant cell fate shift and improvement in cardiomyocyte maturation status upon-multilineage co-culture. Ligand-receptor analysis identified DLK1-Notch signaling to be one of the most upregulated pathways in the fibroblast population. Modulate the activity of DLK1-Notch signaling affected the assembly of the mini-cardiac organoid and the expression of immune regulatory genes. Interestingly, transplantation of trilineage mini-cardiac organoid into a rat model of myocardial infarction leads to significant improvement of cardiac function. Collectively, our single-cell analysis of mini-cardiac organoid provided rich information about cell fate dynamics and multilineage cross-talks occurred in the 3D microenvironment, which bring new insight on the molecular mechanism that promotes cardiomyocyte maturation and heart repair.