Tissue Engineering the Retina: Soft Lithography-Patterned Microchannel PLGA Scaffolds Guide the Morphogenesis of Dissociated Newborn Mouse Retinal Cells and Human Embryonic Stem Cell-Derived Retinal Cultures

While embryonic stem cell-derived photoreceptors promise a cell source for enhanced in vitro models of retinal degenerative diseases, the more differentiated characteristics of retinal cells do not develop in the dissociated cultures typical of ES cells. Therefore, we have attempted to reconstruct organized retinal tissue from dissociated retinal cells into an array of aligned units that more faithfully mimics the retina. We report the first attempt to solvent-process poly(lactic-co-glycolic acid) 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 and with low serum significantly increased infiltrated cell viability compared to submerged cultures, resulting in 12.3 +/- 1.70 cells per channel after three days and 10.7 +/- 0.80 cells per channel after seven days. Rod photoreceptors and Müller glia aligned processes parallel to the microchannel walls. Otx2+ and Pax6+ subpopulations recapitulated lamination behavior. We constructed scaffold/retinal pigment epithelium explants and observed rods extending rhodopsin-positive processes toward RPE cells. Finally, human embryonic stem cell-derived photoreceptors exhibited infiltration and morphological characteristics similar to mouse retinal cells inside the scaffolds. These findings further efforts to generate tissue-level retinal models from dissociated cells for use in a variety of applications.