Pluripotent Stem Cell-Based Approaches to Explore and Treat Optic Neuropathies

Abstract

Sight is a major sense for human and visual impairment profoundly affects quality of life, especially retinal degenerative diseases which are the leading cause of irreversible blindness worldwide. As for other neurodegenerative disorders, almost all retinal dystrophies are characterized by the specific loss of one or two cell types, such as retinal ganglion cells, photoreceptor cells, or retinal pigmented epithelial cells. This feature is a critical point when dealing with cell replacement strategies considering that the preservation of other cell types and retinal circuitry is a prerequisite. Retinal ganglion cells are particularly vulnerable to degenerative process and glaucoma, the most common optic neuropathy, is a frequent retinal dystrophy. Cell replacement has been proposed as a potential approach to take on the challenge of visual restoration, but its application to optic neuropathies is particularly challenging. Many obstacles need to be overcome before any clinical application. Beyond their survival and differentiation, engrafted cells have to reconnect with both upstream synaptic retinal cell partners and specific targets in the brain. To date, reconnection of retinal ganglion cells with distal central targets appears unrealistic since central nervous system is refractory to regenerative processes. Significant progress on the understanding of molecular mechanisms that prevent central nervous system regeneration offer hope to overcome this obstacle in the future. At the same time, emergence of reprogramming of human somatic cells into pluripotent stem cells has facilitated both the generation of new source of cells with therapeutic potential and the development of innovative methods for the generation of transplantable cells. In this review, we discuss the feasibility of stem cell-based strategies applied to retinal ganglion cells and optic nerve impairment. We present the different strategies for the generation, characterization and the delivery of transplantable retinal ganglion cells derived from pluripotent stem cells. The relevance of pluripotent stem cell-derived retinal organoid and retinal ganglion cells for disease modeling or drug screening will be also introduced in the context of optic neuropathies.

Dual SMAD inhibition and Wnt inhibition enable efficient and reproducible differentiations of induced pluripotent stem cells into retinal ganglion cells

“…[63] The RGC survival in these ROs derived retinal cultures decreased in vitro as the culture time was extended as floating cultures were a hinderance to the normal RGC growth and induced apoptosis. Adherent cultures obtained by enzymatic dissociation of ROs greatly improved the survival of these RGC [64] Several protocols following this study, differentiated iPSCs to neural rosettes and embryoid bodies that were further differentiated into RGCs using chemically defined media. [28,56,64,65] These methods have several shortcomings for large scale growth and culture of RGCs as, they not only introduce bias during manual selection of desired RPCs, but also introduce variability in the total numbers or RGCs produced resulting from RPC numbers used for differentiation.…”

“…Adherent cultures obtained by enzymatic dissociation of ROs greatly improved the survival of these RGC [64] Several protocols following this study, differentiated iPSCs to neural rosettes and embryoid bodies that were further differentiated into RGCs using chemically defined media. [28,56,64,65] These methods have several shortcomings for large scale growth and culture of RGCs as, they not only introduce bias during manual selection of desired RPCs, but also introduce variability in the total numbers or RGCs produced resulting from RPC numbers used for differentiation. Hence to reduce variability and increase the efficiency of the RGC generation, we differentiate the entire iPSC culture vessel to RPCs, and use a crosshatching technique that does not need manual selection/screening to produce abundant RPC clumps that can be readily differentiated into RGCs.…”

Curcumin as a Therapeutic Option in Retinal Diseases

“…The group of ocular diseases labeled as glaucoma are subdivided in subcategories, being the most prevalent open-angle glaucoma, in which, the aqueous humor does not drain, although the trabecular meshwork is not destroyed and the less frequent closed-angle glaucoma and normal tension glaucoma [56]. Current treatments try to lower the intraocular pressure; and try to restore the RGC population transplanting stem cells, but in many cases the transplanted cells stay undifferentiated [57].…”

Generation of a Transplantable Population of Human iPSC-Derived Retinal Ganglion Cells

“…Therefore, human pluripotent stem cells (hPSCs) represent one of the most promising sources of human RGCs. Recent development of methods guiding the differentiation of hPSCs toward specific retinal lineages, including RGCs, has emerged as a powerful strategy for disease modeling, drug screening, and gene or cell therapy (Llonch et al, 2018;Rabesandratana et al, 2018;Miltner and La Torre, 2019;Ahmad et al, 2020). Previous studies have demonstrated the ability to differentiate RGCs from plated hPSC-derived embryoid bodies (Riazifar et al, 2014;Sluch et al, 2015;Gill et al, 2016;Teotia et al, 2017).…”