The Impact Of Bone Marrow Mesenchymal Stem Cells On Human Retinal Pigment Epithelialium Cells Apoptosis Induced By Light Damage

Objective To investigate human retinal pigment epithelium(h RPE) cells apoptosis after intensive light exposure and potential therapeutic effect of bone marrow mesenchymal stem cells(MSCs) against light-induced damage in h RPE cells.Method Immunocytochemistry was conducted to identify h RPE cells specific marker CK-18 expression. Cells were seeded at a density of 1.5*105 cells/well in 6-well plates. Upon attachment, the cells were exposed to 12600±500 lx illumination for 2 hours to establish light damage model. After light exposure, h RPE cells were followed by MSCs-conditioned medium or MSCs-h RPE coculture for 24 hours and 48 hours. Morphological changes in h RPE cells were observe under microscope. Apoptosis of h RPE cells were detected via TUNEL and flowcytometry. The supernatant of h RPE cells was assayed for LDH concentration using ELISA.Result 1. The cell count significantly reduced after intensive light exposure for 24 hours and 48 hours. The Morphological changes were observed as cytoplasma shrinking together with nuclea gathering. Reduced attachment and cell fragment were also identified. Light exposed cells were detected increased in TUNEL positive rate in comparison with normal group(P< 0.05). Significant difference in TUNEL positive rate also existed between 24-hour and 48-hour light exposure(P< 0.05). The results were confirmed using flowcytometry. 2. In contrast to h RPE cells that were grouped in merely light exposure, the conditioned medium group and cocultured group were identified decreased LDH level in the supernatants and reduced apoptosis rate in both 24-hour and 48-hour duration(all P< 0.05).3. Compared intervention 24-hour to 48-hour, we found that the reduction of LDH concentration levels of h RPE cells supernatant and TUNEL positive cells rate in co-culture group is higher than that of conditioned medium group, with statistical significance(P < 0.05).Flowcytometry technology testing shows that the volume of cell apoptosis reduced.Conclusion Light exposure induced apoptosis in h RPE cells. Both MSCs-conditioned medium and MSCs coculture were able to reduce apoptosis in h RPE cells after light exposure. Among which, MSCs coculture revealed a superior effect against apoptosis in intensive light-exposed h RPE cells.