Investigation of Retinal Ganglion Cell Diversity and Subtype Specification from Human Pluripotent Stem Cells

Abstract

Purpose : Retinal ganglion cells (RGCs) provide a vital connection between the eye and the brain, and damage to these cells is associated with a number of blinding disorders. While this function is shared among nearly all RGCs, this class of cells is comprised of multiple subtypes which have been recently identified by their expression of specific molecular markers. The ability to derive RGCs from human pluripotent stem cells (hPSCs) would allow for the in vitro analysis of these cells as well as how they may be adversely affected in developmental and degenerative disorders of the visual system. Thus, efforts were undertaken to examine the ability to direct the differentiation of hPSCs to each of the major classes of RGC subtypes.

Methods : hPSCs were differentiated following a predicted, stepwise protocol that closely mimics the major stages of human retinogenesis. At selected time points over a period of eighty days, immunocytochemistry analyses were performed to characterize the derivation of retinal ganglion cell types based on specific molecular markers. Further characterization of these cells was performed by qPCR analysis to test the combinatorial expression of molecular markers associated with the major classes of RGC subtypes.

Results : RGCs were initially identified within the first 40 days of differentiation based on the expression of the BRN3 transcription factor. Prolonged growth and differentiation of these cells yielded elaborate and lengthy neurite extensions, characteristic of RGCs. Retinal ganglion cell subtypes were molecularly characterized by expression of transcription factors and proteins using immunocytochemistry, including direction selective RGCs, alpha RGCs, and intrinsically photosensitive RGCs. Additionally, qPCR analysis verified the differentiation of these RGC subtypes through the combinatorial expression of cell type-specific molecular markers.

Conclusions : The results of this study demonstrate the ability of hPSCs to effectively differentiate into a variety of RGC subtypes. As such, these cells will facilitate a more comprehensive study of human retinal ganglion cell development. Furthermore, when derived from patient-specific cell lines, these results will enable a more detailed analysis of the effects of neurodegenerative disorders upon each of these classes of RGC subtypes.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.