Project description:Transplantation of GABAergic interneurons (INs) can sustain long-standing benefits in animal models of epilepsy and other neurological disorders. In a therapeutic perspective, a renewable source of functional GABAergic INs is needed. Here, we identified five factors (Foxg1, Sox2, Ascl1, Dlx5 and Lhx6) able to convert fibroblasts directly into induced GABAergic INs (iGABA-INs), displaying the molecular signature of telencephalic INs. The selected factors recapitulate in fibroblasts the activation of transcriptional networks required for the specification of GABAergic fate during telencephalon development. iGABA-INs exhibited progressively maturing firing patterns comparable to those of cortical INs, had synaptic currents and released GABA. Importantly, upon grafting in the hippocampus, iGABA-INs survived, matured and their optogenetic stimulation triggered GABAergic transmission and inhibited the activity of connected granule cells. The five factors also converted human cells into functional GABAergic neurons. These properties define iGABA-INs as a promising tool for disease modeling and cell-based therapeutic approaches. Comparison of iGABA-INs transcriptional profile with those of starting fibroblasts and GAD67-GFP+ cortical interneurons.
Project description:Direct cell reprogramming has enabled the direct conversion of skin fibroblasts into functional neurons and oligodendrocytes using a minimal set of cell lineage-specific transcription factors. This approach has substantial advantages since it is rapid and simple, generating the cell type of interest in a single step. However, it remains unknown whether this technology can be applied for directly reprogramming skin cells into astrocytes, the third neural lineage. Astrocytes play crucial roles in neuronal homeostasis and their dysfunctions contribute to the origin and progression of multiple human diseases. Herein, we carried out a screening using several transcription factors involved in defining the astroglial cell fate and identified NFIA, NFIB and SOX9 to be sufficient to convert with high efficiency embryonic and post-natal mouse fibroblasts into astrocytes (iAstrocytes). We proved both by gene expression profiling and functional tests that iAstrocytes are comparable to native brain astrocytes. This protocol can be then employed to generate functional iAstrocytes for a wide range of experimental applications. Induced astrocytes (iAstro) were compared to Fibroblasts (Fibro) as negative control and to primary astrocytes (astro) as positive control. Three biological replicates were analyzed for each experimental group.
Project description:Recent advances in direct reprogramming using cell type-specific transcription factors provide an unprecedented opportunity for rapid generation of desired human cell types from easily accessible tissues. However, due to the diversity of conversion factors that facilitate the process, an arduous screening step is inevitable to find the appropriate combination(s). Here, we show that under chemically defined conditions minimal pluripotency factors are sufficient to directly reprogram human fibroblasts into stably self-renewing neural progenitor/stem cells (NSCs), but without passing through a pluripotent intermediate stage. These NSCs can be expanded and propagated in vitro without losing their potential to differentiate into various neuronal subtypes and glia. Our direct reprogramming strategy represents a simple and advanced paradigm of direct conversion that will provide an unlimited source of human neural cells for cell therapy, disease modeling, and drug screening. We used microarray to compare the global gene expression pattern between human fibroblasts and human neural epitheliums from human ESCs or directly from fibroblasts. We cultured cells and harvested them and then extracted total RNA for microarray.
Project description:Recent reports have proposed a new paradigm for obtaining mature somatic cell types from fibroblasts without going through a pluripotent state, by briefly expressing canonical iPSC reprogramming factors Oct4, Sox2, Klf4 and c-Myc (abbreviated as OSKM), in cells expanded in lineage differentiation promoting conditions. Here we apply genetic lineage tracing for endogenous Nanog, Oct4 and X chromosome reactivation during OSKM induced trans-differentiation, as these molecular events mark final stages for acquisition of induced pluripotency. Remarkably, the vast majority of reprogrammed cardiomyocytes or neural stem cells derived from mouse fibroblasts via OSKM mediated trans-differentiation were attained after transient acquisition of pluripotency, and followed by rapid differentiation. Our findings underscore a molecular and functional coupling between inducing pluripotency and obtaining “trans-differentiated” somatic cells via OSKM induction, and have implications on defining molecular trajectories assumed during different cell reprogramming methods. poly RNA-Seq was measured before, during and after conversion of mouse embryonic fibroblasts to neural stem cells using OSKM trans-differentiation method.
Project description:Forced expression of pro-neural transcription factors was shown to mediate direct neuronal conversion of human fibroblasts. Since neurons are postmitotic, the conversion efficiency represents an important parameter. Here we present a minimalist approach combining two factor neuronal programming with small molecule-based inhibition of GSK3ß and SMAD signaling, which gives rise to functional neuron-like cells (iNs) of various neurotransmitter phenotypes with an overall yield of up to >200% and a final neuronal purity of up to >80%. Timcourse of reprogramming of fibroblasts towards an neuronal phenotype in two independent fibroblast lines
Project description:Direct cell reprogramming has enabled the direct conversion of skin fibroblasts into functional neurons and oligodendrocytes using a minimal set of cell lineage-specific transcription factors. This approach has substantial advantages since it is rapid and simple, generating the cell type of interest in a single step. However, it remains unknown whether this technology can be applied for directly reprogramming skin cells into astrocytes, the third neural lineage. Astrocytes play crucial roles in neuronal homeostasis and their dysfunctions contribute to the origin and progression of multiple human diseases. Herein, we carried out a screening using several transcription factors involved in defining the astroglial cell fate and identified NFIA, NFIB and SOX9 to be sufficient to convert with high efficiency embryonic and post-natal mouse fibroblasts into astrocytes (iAstrocytes). We proved both by gene expression profiling and functional tests that iAstrocytes are comparable to native brain astrocytes. This protocol can be then employed to generate functional iAstrocytes for a wide range of experimental applications.
Project description:Direct conversion of fibroblasts to induced cardiomyocytes (iCMs) has great potential for regenerative medicine. Recent publications have reported significant progress, but the evaluation of reprogramming has relied upon non-functional measures such as flow cytometry for cardiomyocyte markers or GFP expression driven by a cardiomyocyte-specific promoter. The issue is one of practicality: the most stringent measures - electrophysiology to detect cell excitation and the presence of spontaneously contracting myocytes - are not readily quantifiable in the large numbers of cells screened in reprogramming experiments. However, excitation and contraction are linked by a third functional characteristic of cardiomyocytes: the rhythmic oscillation of intracellular calcium levels. We set out to optimize direct conversion of fibroblasts to iCMs with a quantifiable calcium reporter to rapidly assess functional transdifferentiation. We constructed a reporter system in which the calcium indicator GCaMP is driven by the cardiomyocyte-specific Troponin T promoter. Using calcium activity as our primary outcome measure, we compared several published combinations of transcription factors along with novel combinations in mouse embryonic fibroblasts. The most effective combination consisted of Hand2, Nkx2.5, Gata4, Mef2c, and Tbx5 (HNGMT). This combination is >50-fold more efficient than GMT alone and produces iCMs with cardiomyocyte marker expression, robust calcium oscillation, and spontaneous beating that persists for weeks following inactivation of reprogramming factors. HNGMT is also significantly more effective than previously published factor combinations for the transdifferentiation of adult mouse cardiac fibroblasts to iCMs. Quantification of calcium function is a convenient and effective means for the identification and evaluation of cardiomyocytes generated by direct reprogramming. Using this stringent outcome measure, we conclude that HNGMT produces iCMs more efficiently than previously published methods. Mouse embryonic fibroblasts were treated with different combinations of transcription factors to drive transdifferentiation to induced cardiomyocytes (iCMs). Putative iCMs were enriched by zeocin selection. Zeocin resistance was conferred to iCMs via the TroponinT-GCaMP5-Zeo lentiviral reporter.
Project description:Recent reports have proposed a new paradigm for obtaining mature somatic cell types from fibroblasts without going through a pluripotent state, by briefly expressing canonical iPSC reprogramming factors Oct4, Sox2, Klf4 and c-Myc (abbreviated as OSKM), in cells expanded in lineage differentiation promoting conditions. Here we apply genetic lineage tracing for endogenous Nanog, Oct4 and X chromosome reactivation during OSKM induced trans-differentiation, as these molecular events mark final stages for acquisition of induced pluripotency. Remarkably, the vast majority of reprogrammed cardiomyocytes or neural stem cells derived from mouse fibroblasts via OSKM mediated trans-differentiation were attained after transient acquisition of pluripotency, and followed by rapid differentiation. Our findings underscore a molecular and functional coupling between inducing pluripotency and obtaining “trans-differentiated” somatic cells via OSKM induction, and have implications on defining molecular trajectories assumed during different cell reprogramming methods. poly RNA-Seq and Chromatin accesibility (ATAC-seq) were measured during conversion of mouse embryonic fibroblasts to neural stem cells using OSKM trans-differentiation method, as well as in mouse emrbyonic fibroblasts, iPSCs and mouse ESCs.
Project description:Recent reports have proposed a new paradigm for obtaining mature somatic cell types from fibroblasts without going through a pluripotent state, by briefly expressing canonical iPSC reprogramming factors Oct4, Sox2, Klf4 and c-Myc (abbreviated as OSKM), in cells expanded in lineage differentiation promoting conditions. Here we apply genetic lineage tracing for endogenous Nanog, Oct4 and X chromosome reactivation during OSKM induced trans-differentiation, as these molecular events mark final stages for acquisition of induced pluripotency. Remarkably, the vast majority of reprogrammed cardiomyocytes or neural stem cells derived from mouse fibroblasts via OSKM mediated trans-differentiation were attained after transient acquisition of pluripotency, and followed by rapid differentiation. Our findings underscore a molecular and functional coupling between inducing pluripotency and obtaining “trans-differentiated” somatic cells via OSKM induction, and have implications on defining molecular trajectories assumed during different cell reprogramming methods. WGBS (Whole-Genome-Bisulfite-sequencing) were measured during conversion of mouse embryonic fibroblasts to neural stem cells using OSKM trans-differentiation method, as well as in mouse emrbyonic fibroblasts, and mouse ESCs.
Project description:Recent advances in direct reprogramming using cell type-specific transcription factors provide an unprecedented opportunity for rapid generation of desired human cell types from easily accessible tissues. However, due to the diversity of conversion factors that facilitate the process, an arduous screening step is inevitable to find the appropriate combination(s). Here, we show that under chemically defined conditions minimal pluripotency factors are sufficient to directly reprogram human fibroblasts into stably self-renewing neural progenitor/stem cells (NSCs), but without passing through a pluripotent intermediate stage. These NSCs can be expanded and propagated in vitro without losing their potential to differentiate into various neuronal subtypes and glia. Our direct reprogramming strategy represents a simple and advanced paradigm of direct conversion that will provide an unlimited source of human neural cells for cell therapy, disease modeling, and drug screening. We used microarray to compare the global gene expression pattern between human fibroblasts and human neural epitheliums from human ESCs or directly from fibroblasts.