TIMP-1 production by bovine retinal pigment epithelial cells increases in response to cyclic mechanical stretch

Purpose: The effect of mechanical stretch was examined on cultured retinal pigment epithelial (RPE) cells in order to observe changes in their production of tissue inhibitor of metalloproteinase-1 (TIMP-1) and vascular endothelial growth factor (VEGF) in response to physiological strain. Methods: Bovine RPE cells in near-confluent culture were exposed to mechanical stretch of the bottom of a 6-cm petri dish at the maximum magnitude of 4500 microstrain and at a cycle of 30 seconds for 72 hours. TIMP-1 and VEGF levels in the medium following 24, 48, and 72 hours of cyclic stretch were measured by enzyme immunoassay. Results: The growth of RPE cells during the 72-hour period of stretching did not show a significant difference from that of nonstretched control cells. RPE cells in the stretched group produced a significantly larger amount of TIMP-1 at 48 and 72 hours after stretch, compared with nonstretched control (P = .044 and P = .027, respectively, Student t-test). The levels of VEGF produced by RPE cells were not significantly different between the stretched group and nonstretched control group. Conclusions: The secretion of TIMP-1 by bovine RPE cells was enhanced by cyclic mechanical stretch. Mechanical strain is one factor in regulating the secretion of TIMP-1 by RPE cells.