Long-term cone and ganglion cell survival in organotypic culture of the human fovea and central retina

Abstract

Purpose: Animal models provide useful research tool for investigation of retinal function and diseases, yet the results of these experiments are often difficult to extrapolate to the human where central photopic vision is dependent on the functional integrity of the central retinal regions and the fovea. Previously, we have shown that in appropriate culture system the human retina can be kept alive with near normal morphology for several weeks. In this study we examine the long-term survival of the cone and ganglion cell populations in human organotypic retinal cultures prepared from the fovea and other central retinal regions.

Methods: Adult human eyes with very short (2-4 h) post mortem intervals were used in this study. The fovea and parts of the central retina were dissected free from the pigment epithelium and were cut into approximately 5x5 mm pieces. The pieces were placed on polycarbonate membranes and were cultured in serum-free medium for up to 7 weeks. The cultures were fixed in different time points and were analyzed by immunohistochemistry. The number and staining characteristics of cone- and ganglion cell types were studied in detail.

Results: The overall retinal morphology was well preserved even after seven weeks. All layers were maintained, all retinal cell types survived and their morphology was comparable to in vivo controls. In the central retina the number of M- and L-cones was near normal. Many M- and L-cones retained their outer segments even after six weeks. The morphology of S-cones was clearly inferior to M- or L-cones, but also they survived in decreased number for seven weeks. To our surprise, in contrast to other literature data, ganglion cells were also detectable in fairly high numbers during the entire culturing period. A significant percentage of the ganglion cells that survived for seven weeks were located in the IPL. Foveas were cultured for two weeks. The general architecture of the fovea was intact, with cone/rod ratios close to the normal values. Ganglion cells were also preserved in high numbers.

Conclusions: Even the most sensitive cell types of the human retina can be maintained in culture at least for 7 weeks. Our model allows the long-term investigation of the retina with preserved cytoarchitecture and therefore could be a preferable model in a wide variety of experiments.