Induction of vascular endothelial growth factor after application of mechanical stress to retinal pigment epithelium of the rat in vitro

PURPOSE. To investigate the response to mechanical stress of vascular endot helial growth factor (VEGF) production by cultured retinal pigment epitheli al (RPE) cells. METHODS. A pulsatile stretch device was used in vitro. RPE cells of the sec ond passage were seeded onto flexible-bottomed culture plates; then, at sub confluent culture, the plates were subjected to pulsatile stretch. Culture plates prepared in the same way but not subjected to stretch were used as c ontrols. After stretching for 1 hour or 24 hours, conditioned medium for me asurement of VEGF production by RPE cells was collected using a mouse VEGF immunoassay. To Study the expression of VEGF in RPE cells, passaged-culture d RPE cells were exposed to pulsatile stretch for 0, 1, 3, or 14 hours. Tot al cytoplasmic RNA was then prepared from the RPE cells. Northern blot anal ysis was performed for VEGF, with G3PDH used as an internal control. RESULTS. The expression and secretion of VEGF in RPE cells were increased b y pulsatile stretching. CONCLUSIONS. Results indicate that stretching of the RPE could result in in creased production of VEGF, with associated risk for neovascularization and changes in the blood-retinal barrier.