Isolation of photoreceptors in the cultured full-thickness fetal rat retina.

Purpose: To create a retina consisting mainly of photoreceptors for future use as donor tissue in retinal transplantation.

Methods: Fetal full-thickness neuroretinas from Sprague-Dawley embryonic day (E) 17 or E20 rats were placed in culture for 7 or 14 days. Explants and age-matched control retinas were examined by light microscopy and with a panel of immunohistochemical markers labeling all seven of the major retinal cell types.

Results: E17 and E20 control retinas displayed vimentin-labeled Müller cells, NF160-labeled ganglion cells, and synaptic vesicles labeled with synaptophysin. The remaining cell types were found in control specimens of postnatal age 2 days and older. After 7 or 14 days in culture, all explants were significantly thinner than their aged-matched controls and displayed multiple rows of cells organized in a single layer. Within this layer, they contained rhodopsin-labeled rod photoreceptors, presynaptic vesicles, and vertically arranged Müller cells. Transducin-labeled cone photoreceptors were found in all but the youngest explants. Scattered PKC-labeled rod bipolar cells and calbindin-labeled horizontal cells were found in the inner part of most explants, whereas beta-III-tubulin-labeled ganglion cells and parvalbumin-labeled amacrine cells were seen only sporadically. No NF160-labeled ganglion cells were found.

Conclusions: Fetal full-thickness rat retina in vitro develops into a retina consisting of predominantly synapse-containing cone and rod photoreceptors embedded in a scaffold of well-organized Müller cells. These explant retina characteristics are well adapted for use as donor tissue in future retinal transplantation experiments.