The organization of human retinal pigment epithelium in vitro

Abstract

The in vitro growth characteristics of retinal pigment epithelium from post mortem human eyes have been described. Our studies demonstrated that only a small percentage of the RPE cells initially plated out enter the division phase 12–21 days after plating and give rise to confluent cultures. The duration of the initial lag phase and the size of the proliferative fraction are age-dependent; cultures established from younger donor eyes have a larger fraction of proliferating cells and enter the division phase earlier than those from older donor eyes. Using the melano-lipofuscin granules as cell markers, we identified two distinct cell populations in the confluent cultures. One population consisted of small, diploid, non-pigmented cells that were undergoing division; the second, larger, densely pigmented cells that appeared stationary. Electron microscopy studies confirmed that both cell populations are epithelial-like in ultrastructure and that the RPE cells in vitro retain many of their in vivo ultrastructural characteristics.