Abstract
Embryonic stem (ES) cell-derived photoreceptors are a promising cell source for enhanced in vitro models of retinal degenerative diseases, but the more differentiated characteristics of retinal cells do not typically develop in dissociated cell cultures. Therefore, we have reconstructed organized retinal tissue by seeding dissociated cells into an array of aligned units that more faithfully mimics the retina. We solvent-processed poly(lactic-co-glycolic acid) (PLGA) into a microchannel scaffold format to achieve this geometric constraint. We compared the effect of PLGA concentration on channel morphology and, along with other culture conditions, on the infiltration of dissociated newborn mouse retinal cells into the channels. Culturing scaffolds at the gas-liquid interface with low serum media increased infiltrated rod photoreceptor viability 18-fold over submerged, high serum cultures when evaluated after seven days. Rod photoreceptors and Müller glia aligned processes parallel to the microchannel walls. Otx2+ and Pax6+ subpopulations recapitulated lamination behavior. Further, we constructed scaffold/retinal pigment epithelium (RPE) co-cultures and observed rods extending rhodopsin-positive processes toward RPE cells, mimicking normal rod polarization and morphology. Finally, human embryonic stem cell-derived photoreceptors exhibited infiltration and morphological characteristics similar to mouse retinal cells inside the scaffolds. These findings constitute an important advance in generating tissue-level retinal models from dissociated cells for use as drug screening platforms and in regenerative medicine.