Mechanical stretch upregulates IGFBP-1 secretion from decidualized endometrial stromal cells

Decidualization is an essential process of endometrial differentiation for embryo implantation and maintenance of pregnancy. Recently, uterine movement-induced mechanical stress was noticed to have possible effects on endometrial functions. In this study, we addressed the possible effect of mechanical stress on the process of decidualization of endometrial stromal cells (ESC). ESC were cultured on flexible-bottomed culture plates. After decidualization was achieved with estradiol and progesterone for 12 days, cultures were continued for 24 h with or without cyclic stretch (25% elongation) in serum-free conditions at a rate of 2 cycles/min using a computer-operated cell tension system. Concentrations of insulin-like growth factor-binding protein-1 (IGFBP-1), a marker of decidualization, in the conditioned medium were measured by specific ELISA, and IGFBP-1 mRNA expression in the ESC was measured by RT-PCR. Cyclic stretch remarkably increased IGFBP-1 secretion from decidualized ESC. It also increased IGFBP-1 mRNA in decidualized ESC. The increase in IGFBP-1 secretion was inhibited by actinomycin D but not by indomethacin, PD-98059, or H-89. Conditioned medium of decidualized ESC cultured with cyclic stretch increased IGFBP-1 secretion from decidualized ESC cultured under stationary conditions. These findings imply that uterine movement modulates decidualization of the endometrium and has a regulatory effect on reproduction.