A new, simple method for isolating retinal pigment epithelial (RPE) ce
lls from rat eyeballs was developed: incubation of the eyeballs in 0.1
% proteinase K solution. This method yielded an average of 4 x 10(4) v
iable RPE cells from each Sprague-Dawley rat eyeball in 1 h. These RPE
cells were hexagonal and had cytokeratin in their cytoplasm and numer
ous microvilli on their surface, similar to RPE cells evaluated in viv
o. The results of this study thus show that our method for incubating
eyeballs in proteinase K can provide good-quality RPE cells in suffici
ent quantities for study in a short time.