Xeno-free generation of human embryonic stem cells into retinal pigment epithelial cells and their integration as a polarized monolayer in a preclinical model

Abstract

Purpose: Transplantation of human embryonic stem cell (hESC) derived retinal pigment epithelial (RPE) cells could be used to replace the tissue lost in the degenerative form of macular degeneration. The production of functional RPE cells have however not been generated in a xeno-free and defined manner which is critical for clinical compliance and to reduce immunogenicity.

Methods: Building on our recently developed methodology for xeno-free derivation of hESC, we now present in vitro differentiation into RPE cells by using a human recombinant laminin-based matrix and a xeno-free, chemically defined medium. Briefly, hESC are differentiated as embryoid bodies in suspension. Optic vesicle-like structures containing pigmented cells emerge following three weeks of differentiation and are manually isolated two weeks later. Enzymatically dissociated single cells are subsequently cultured in 2D cultures on laminin. Suspensions of differentiated cells were transplanted into albino rabbits and cell fate was analyzed by real-time high-resolution imaging and immunohistochemistry.

Results: This approach yields highly homogeneous populations of mature hESC-derived RPE cells that exhibit characteristics of native RPE cells such as morphology, pigmentation, expression and polarization of specific markers and phagocytic activity. Furthermore, upon subretinal transplantation into immunosuppressed albino rabbits, these cells form an organized, polarized and pigmented epithelial layer with maintained expression of RPE markers.

Conclusions: ​Altogether, these findings prove that our xeno-free and chemically defined differentiation method could serve as a potential source of clinically compliant RPE cells for the development of a safe and efficient cell replacement therapy for age-related macular degeneration.