Project description:Since retinal ganglion cells (RGCs) do not regenerate after injury, RGC replacement therapy could provide an approach to vision restoration in glaucoma and other optic neuropathies. Here we developed a rapid protocol for direct induction of RGC (iRGC) differentiation from human iPSCs and ESCs in less than two weeks, by overexpression of NGN2 in RGC survival-promoting medium supplemented with a Notch inhibitor. Neuronal morphology and neurite growth were observed within one week of induction. Immunostaining and qRT-PCR for characteristic RGC-specific genes confirmed identity. Calcium imaging was used to evaluate iRGCs’ electrophysiologic maturation, and demonstrated GABA-induced excitatory calcium influx characteristic of immature RGCs. Using single cell-RNA sequencing (scRNA-seq) we further delineated iRGCs’ differentiation and compared iRGC transcriptomic profiles to fetal human and retinal organoid-derived RGCs. Unbiased clustering showed high similarities of transcriptomic profiles among iRGCs, early-stage fetal human RGCs and early-stage retinal organoid-derived RGCs. However, for some markers, including BRN3a, BRN3b and NEFL, iRGCs demonstrated expression patterns more similar to fetal RGCs than to retinal organoid RGCs. After intravitreal injection into rodent eyes, transplanted iRGCs survived and migrated into host retinas where they were detected one week and one month after transplant. Prior optic nerve trauma to the recipient host did not significantly enhance or detract from iRGC integration, but iRGCs protected host RGCs from neurodegeneration. Taken together, these data demonstrate rapid iRGC generation in vitro into an immature cell with high similarity to human fetal RGCs and capacity for retinal integration after transplant, including after optic nerve injury. The simplicity of this system may benefit translational studies on human RGCs.
Project description:The neuronal cell death results in neurodegenerative diseases. The extracellular environment plays a critical role in regulating cell viability. In this study, we explore how intercellular communication contributes to the survival of retinal ganglion cells (RGCs) following the optic nerve crush (ONC). By performing single-cell RNA-seq on whole retinal cells, we observed transcriptomic responses in non-RGC retinal cells to the injury, with astrocytes and Müller glia having the most interactions with RGCs. By comparing the RGC subclasses showing distinct resilience cell death, we identified top 47 interactions that are stronger in the high-survival RGCs, likely representing neuroprotective interactions. We performed functional assays on one of the receptors, Mu-opioid receptor (Oprm1). Although Oprm1 is preferentially expressed in intrinsically photosensitive retinal ganglion cells (ipRGCs), its neuroprotective effect could be transferred to multiple RGC subclasses by specific overexpressing Oprm1 in pan-RGCs. Our study provides an atlas of cell-cell interactions in both intact and post-ONC retina and an effective strategy to predict molecular mechanisms in neuroprotection, underlying the principal role played by extracellular environment in supporting neuron survival.
Project description:To gain a deeper insight into roles of Arid1a in injured retinal ganglion cells (RGCs), we performed ATAC-seq and RNA-seq to analyze the genome-wide changes of chromatin accessibility and transcriptome changes before and after Arid1a deletion in RGCs of the adult mouse using Cre-lox system.
Project description:Through a comparative analysis of RGC subclasses exhibiting varying levels of resilience to cell death, based on cell-cell interaction analysis, we identified the Mu-opioid receptor, encoded by the Oprm1 gene, as a novel neuroprotective factor for pan-RGCs. Functionally and with the sequencing dataset deposited here, we validated Oprm1 as a neuroprotective factor for RGCs, by demonstrating that overexpression of Oprm1 in RGCs not only led to a markedly increased survival rate of RGCs following several different types of retinal injuries, but also significantly improved visually-guided perception behaviors.
Project description:Retinal ganglion cell (RGC) replacement therapy could restore vision in glaucoma and other optic neuropathies. We developed a rapid protocol for directly induced RGC (iRGC) differentiation from human stem cells, leveraging overexpression of NGN2. Neuronal morphology and neurite growth were observed within 1 week of induction; characteristic RGC-specific gene expression confirmed identity. Calcium imaging demonstrated γ-aminobutyric acid (GABA)-induced excitation characteristic of immature RGCs. Single-cell RNA sequencing showed more similarities between iRGCs and early-stage fetal human RGCs than retinal organoid-derived RGCs. Intravitreally transplanted iRGCs survived and migrated into host retinas independent of prior optic nerve trauma, but iRGCs protected host RGCs from neurodegeneration. These data demonstrate rapid iRGC generation in vitro into an immature cell with high similarity to human fetal RGCs and capacity for retinal integration after transplantation and neuroprotective function after optic nerve injury. The simplicity of this system may benefit translational studies on human RGCs.
Project description:Analysis of retinal ganglion cells (RGCs) by scRNA-seq is emerging as a state-of-the-art method for studying RGC biology and subtypes, as well as for studying the mechanisms of neuroprotection and axon regeneration in the central nervous system (CNS). Rbpms has been established as a pan-RGC marker, and Spp1 has been established as an αRGC type and macrophage marker. Here, we analyzed by scRNA-seq retinal microglia and macrophages, and found Rbpms+ subpopulations of retinal microglia/macrophages, which pose a potential pitfall in scRNA-seq studies involving RGCs. We performed comparative analysis of cellular identity of the presumed RGC cells isolated in recent scRNA-seq studies, and found that Rbpms+ microglia/macrophages confounded identification of RGCs. We also showed using immunohistological analysis that, Rbpms protein localizes to stress granules in a subpopulation of retinal microglia after optic nerve injury, which was further supported by bioinformatics analysis identifying stress granule-associated genes enriched in the Rbpms+ microglia/macrophages. Our findings suggest that the identification of Rbpms+ RGCs by immunostaining after optic nerve injury should exclude cells in which Rbpms signal is restricted to a subcellular granule, and include only those cells in which the Rbpms signal is labeling cell soma diffusely. Finally, we provide solutions for circumventing this potential pitfall of Rbpm-expressing microglia/macrophages in scRNA-seq studies, by including in RGC and αRGC selection criteria other pan-RGC and αRGC markers.
Project description:We report the genome-wide RNA sequencing changes to isolated retinal ganglion cells (RGCs) from immunopanned embryonic day 18 (E18) and early postnatal (P5) wildtype mouse retinas. We report the transcriptomic change associated with RGCs in a survival and regenerative state, and use gene-set enrichment analysis (GSEA) to predict the upstream transcription factors likely regulating these observed changes.
Project description:Chrdl1 treatment promotes formation of synapses and GluA2-AMPAR recruitment in Retinal ganglion cell (RGC) cultures. Analysis of the transcriptome of RGCs with or without Chrdl1 treatment let us determine potential alterations in the expression of genes related to BMP signaling, or genes involved in excitatory synaptogenesis and AMPAR trafficking.
Project description:To investigate the neuroprotective role of TGFβR1 in retinal ganglion cells (RGCs), we isolated adult RGCs from TGFβR1flx/flxvglut2-Cre+/- and TGFβR1flx/flxvglut2-Cre-/- mice. We then performed gene expression profiling analysis using data obtained from RNA-seq of 2 different cells.
Project description:Neuronal types in the central nervous system differ dramatically in their resilience to injury or insults. Here we studied selective resilience in mouse retinal ganglion cells (RGCs) following optic nerve crush (ONC), which severs their axons and leads to death of ~80% of RGCs in 2 weeks. To identify expression programs associated with differential resilience, we first used single-cell RNA-seq (scRNA-seq) to generate a comprehensive molecular atlas of 45 RGC types in adult retina. We tracked their survival after ONC, characterized transcriptomic, morphological, and physiological changes that preceded degeneration, and identified genes selectively expressed by each type. Finally, loss- and gain-of-function assays in vivo showed that manipulating some of these genes improved neuronal survival and axon regeneration following ONC. This study provides a systematic framework for parsing type-specific responses to injury, and demonstrates that these responses can be used to reveal molecular targets for intervention.