TIMP-1 production by human scleral fibroblast decreases in response to cyclic mechanical stretching

Purpose: The effect of mechanical stretching was examined on cultured scleral fibroblasts of the human eye in order to observe changes in their production of TIMP (tissue inhibitor of metalloproteinase)-1, MMP (matrix metalloproteinase)-1 and -2 in response to physiological strain. Methods: Human scleral fibroblasts were cultured from scleral tissue resected during foveal translocation surgery. The fibroblasts in near confluency were exposed to mechanical stretching of the bottom of a 6-cm Petri dish at the maximum magnitude of 4500 microstrain and at a cycle of 30 s for 72 h. TIMP-1, MMP-1 and MMP-2 levels in the medium following 24, 48 and 72 h of cyclic stretching were measured by enzyme immunoassay. Results: The growth of scleral fibroblasts during the 72-hour period of stretching did not show a significant difference from that of non-stretched control fibroblasts. Scleral fibroblasts in the stretched group produced a significantly smaller amount of TIMP-1 at 72 h after stretching, compared with nonstretched control (p = 0.0353, Student t-test). The levels of MMP-1 and MMP-2 produced by scleral fibroblasts were not significantly different between the stretched group and nonstretched group. Conclusion: The production of TIMP-1 by human scleral fibroblasts was suppressed by cyclic mechanical stretching. Mechanical strain would be one factor to regulate the homeostasis of extracellular matrix in the sclera.