Biodegradable polymer film as a source for formation of human fetal retinal pigment epithelium spheroids

PURPOSE. TO evaluate the attachment of human fetal retinal pigment epitheli al (HFRPE) cells to a biodegradable polymer film with subsequent formation of spheroids in vitro. METHODS. Ten biodegradable polymer films with different compositions were e xamined for their physical properties and ease of manipulation under a diss ecting microscope. The Nm with the most suitable handling characteristics w as chosen, and a purely isolated sheet of HFRPE cells was attached to it. T he purity of the cells was assessed by their pigmentation and expression of cytokeratin. Proliferation was assessed by incorporation of 5-bromo-2'-deo xyuridine (BrdU). Cellular structure was analyzed under light and electron microscopes, and the functional capability of the cells was evaluated by ro d outer segment (ROS) phagocytosis. RESULTS. The polymer film with composition 50:50 poly (DL-lactide) (PLA)/po ly (DL-lactide-co-glycolide) (PLG) with an inherent viscosity of 1.03 dl/g was found to be the most suitable for handling under the microscope. Sheets of HFRPE cells attached to the polymer films within 48 hours and began to form spheroids. AU the isolated cells were pigmented and expressed cytokera tin. They possessed a cuboidal morphology, numerous apical microvilli, and no sign of dedifferentiation. HFRPE cells produced extracellular matrix (co llagen filaments) on their basal side, filling the cavities of the polymer film. The cells subsequently proliferated, incorporated BrdU, migrated onto the culture plate to form monolayers, and phagocytized ROS. CONCLUSIONS. Biodegradable polymer films can be used as a scaffold for the adhesion of the HFRPE sheet and formation of spheroids. Spheroids represent a source of high density and well-differentiated HFRPE cells that are easy to transfer. Furthermore, the structure of the membrane makes it suitable for additional applications.