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

Abstract

Optic neuropathies are a major cause of visual impairment due to retinal ganglion cell (RGC) degeneration. Human induced-pluripotent stem cells (iPSCs) represent a powerful tool for studying both human RGC development and RGC-related pathological mechanisms. Because RGC loss can be massive before the diagnosis of visual impairment, cell replacement is one of the most encouraging strategies. The present work describes the generation of functional RGCs from iPSCs based on innovative 3D/2D stepwise differentiation protocol. We demonstrate that targeting the cell surface marker THY1 is an effective strategy to select transplantable RGCs. By generating a fluorescent GFP reporter iPSC line to follow transplanted cells, we provide evidence that THY1-positive RGCs injected into the vitreous of mice with optic neuropathy can survive up to 1 month, intermingled with the host RGC layer. These data support the usefulness of iPSC-derived RGC exploration as a potential future therapeutic strategy for optic nerve regeneration.

Retinal Ganglion Cell Transplantation: Approaches for Overcoming Challenges to Functional Integration

“…As such, most efforts to create transplantable donor cells have concentrated on human embryonic stem cell (hESC) and induced pluripotent stem cell (iPSC) derived RGCs. Differentiation methodologies to generate RGCs have been described by numerous protocols and comprehensive reviews [34][35][36][37]. Here, we will only briefly highlight the major developmental pathways and transcriptional events relevant to RGC lineage specification.…”

“…When autologous in origin, iPSCs have a low risk of host rejection, and their use is unencumbered by ethical concerns surrounding human embryo destruction. Numerous protocols exist to direct iPSCs to RPCs and RGC-like cells [34,[50][51][52]. Undifferentiated iPSCs show retinal neuron potentiality when stimulated by DKK1, Noggin, and DAPT, the same factors used in hESC differentiation [53].…”

“…For both experimental purposes and eventual clinical translation, a greater understanding of immunosuppressive requirements for RGC transplantation is needed. Xenotransplantation in rodents has typically utilized systemic immunosuppression with various combinations of cyclosporine-A, azathioprine, and/or prednisone [34,127].…”

“…Without disrupting the ILM in adult rodent recipients, only a small fraction of transplanted mouse RGCs into healthy rodent hosts are able to localize to host retina, but those that do are able to extend axons toward the optic nerve head and dendrites into the IPL [32]. In contrast, most transplanted RGCs do not exhibit distant axon extensions [34,71,74], possibly because they do not localize to the inner retinal parenchyma. Only a subset of published transplantation studies report evidence of donor cell neuritogenesis [32,33,62,70,73,74], and even fewer have described dendritic lamination into the host IPL [32,62].…”

Exploiting hiPSCs in Leber's Hereditary Optic Neuropathy (LHON): Present Achievements and Future Perspectives

“…The use of hiPSCs to obtain terminally differentiated cells of a variety of tissues is a revolutionary approach to understanding disease mechanisms, performing drug screening, and testing gene or cell therapy ( 12 – 15 ).…”