Cell viability assay on cultured retinas of rats and mice.

Mouse retina (A and B) and rat retina (C and D) after 4-day culture were stained with YO-PRO-1 (undergoing apoptotic cell marker). YO-PRO-1 positive cells were clustered along with the edge of cultured retinas of mice and rats (surrounded by arrow heads in A and C). The clusters formed area with bright fluorescence so that we defined a clustered area as a YO-PRO-1 positive area (black areas in B and D). Note: panels (C and D) show most severely damaged rat retina after 4-day culture (12.0% area was positive for YO-PRO-1). Scale bars for (A and B), 500 µm. Scale bars for (C and D), 1 mm. (E) Quantification of YO-PRO-1 positive area on rat and mouse retinas. In the rat retinas, 7.4±3.2% (mean ± standard deviation, n = 4) of the whole retinal area was YO-PRO-1 positive, while 3.7±1.2% (n = 5) of retinal area were also YO-PRO-1 positive even in acutely isolated retina (no significant difference). In the mouse retinas, 17.3±6.9% (n = 4) of the whole retinal area was YO-PRO-1 positive, significantly larger than that of acutely isolated mouse retinas (2.7±0.4%, n = 4). Significant difference was detected in mouse retinas by Student's t-test.