Abstract
Purpose :
Visual dysfunction in age-related macular degeneration (AMD) is associated with the degeneration of retinal pigmental epithelial cells (RPEs). Several ongoing clinical trials are testing cell replacement therapy as means to halt AMD progression, using human pluripotent stem cell (hPSC)-derived RPEs. Although grafted cells pre-transplantation are routinely characterized, it is unknown how these cells respond transcriptionally post-transplantation. In this study, we dissected the single cell transcriptomic changes in hPSC-RPEs after transplantation.
Methods :
Two sources of hPSCs, embryonic (ESCs) and induced (iPSCs), were differentiated to generate RPEs, which were characterized at the mRNA, protein, and functional level to confirm their resemblance to native counterparts. 1-month-old hPSC-RPEs were then either grown further for a month in vitro or subretinally implanted into immunocompetent Dutch Belted rabbits and followed-up for an additional month. At 2 months, both in vitro and in vivo transplanted cells were harvested for single cell RNA sequencing (scRNA-seq).
Results :
The in vitro 1-month-old hPSC-RPE cells expressed RPE signature markers, secreted cytokines in a polarized fashion, and demonstrated barrier function and phagocytosis. These 1-month-old cells were successfully xenografted subretinally into immunocompetent hosts and displayed maintenance of overlying retinal structure, and retinal function. There was absence of adverse reactions against both sources of RPEs. ScRNA-seq of in vitro RPEs from both sources revealed a similar heterogenous population consisting of a spectrum of varying maturity states, from progenitor to late RPE. Profiling of RPE after subretinal transplantation unravelled robust in vivo maturation towards late RPE state.
Conclusions :
In this work, we generated high quality, functional RPEs from two different hPSC sources. Subretinal transplantation of these cells into an immunocompetent host did not elicit an adverse reaction, highlighting hPSCs as a promising cell source to treat AMD. Furthermore, scRNA-seq performed on subretinally transplanted hPSC-RPEs uncovered the favorable maturation of a heterogenous in vitro RPE population towards a homogenous adult state. Overall, our findings provide a high-resolution perspective on a stem cell-based product intended for future clinical use.
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This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.