Development of a biodegradable smooth-surface microcarrier for retinal pigment epithelial cell expansion and maturation

The retinal pigment epithelium (RPE) is essential for the health and function of the retina and, more specifically, the photoreceptors. Hence, the dysfunction of RPE leads to various retinal degeneration diseases. The rising prevalence of these disorders highlights the need for effective, large-scale cell-based therapies, particularly those utilizing stem cell-derived RPE cells. This study presents the development of a biodegradable, smooth surface microcarrier designed to facilitate the expansion and maturation of RPE cells derived from induced pluripotent stem cells (iPSCs). Using a three-dimensional (3D) culture system with polycaprolactone (PCL) porous microcarriers, we demonstrate that RPE cells exhibit comparable adhesion and growth on microcarriers as they do on traditional two-dimensional (2D) culture plates. The microcarrier system facilitates efficient maturation and yields higher quantities of functional RPE cells, highlighting its potential for large-scale production to meet both clinical demands and in vitro large-scale screening studies. Moreover, RPE cells cultured on this microcarrier can be directly frozen and recovered, maintaining their phenotypic and functional integrity upon thawing. This research showcases the scalability and practicality of RPE cell production, providing a robust solution for the storage and delivery of RPE cells. While our results establish the feasibility of direct cryopreservation and recovery of monolayer RPE cells on microcarriers, the designation of a 'ready-to-use' product format is preliminary and will require expanded assessment of long-term functionality, safety, and direct translational outcomes in future studies.