Abstract： Objective To investigate the effects of mechanical stretch on the pelvic floor dysfunction and study the regulation of mechanical stretch on the morphology and extracellular matrix mRNA expression of fibroblasts derived from human uterosacral ligament.Methods 13 patients who underwent hysterectomy surgery due to uterine benign diseases in the Obstetric and Gynecological Department of the Second Hospital of Hebei Medical University from October 2009 to September 2010 and had no pelvic organ prolapse were recruited in this study.Fibroblasts of uterosacral ligament were cultured by collagenase digestion and identified by morphology and immunocytochemical methods.Fibroblasts of 3 ～ 4 generations were stretched by flexcell-4000 tension system for 0,4,15,24 hours.Total RNA was extracted from the fibroblasts and mRNA of Collagen Ⅰ,Collagen Ⅲ,matrix metalloproteinase-1 and tissue inhibitor of metalloprot einase-1were measured with real-time fluorescence quantitative PCR.Results In response to mechanical stretch,the morphology and orientation of the uterosacral ligament fibroblasts were changed as well as their synthetic function.Collagen Ⅰ mRNA for 4 or 15 hours' stretch (0.777 ± 0.251,0.730 ± 0.248)were statistically down regulated compared with 0 hour ( 1.000 ±0.284),( q =4.5786,4.6458,p ＜0.05).But for 24 hours'stretch,the mRNA expression ( 1.102 ±0.308) of collagen Ⅰ restored to the level of 0 hours.The expressions of collagen Ⅲ mRNA for 4,15,24 hours' stretch (4.771 ± 0.879,6.146 ± 1.109,5.022 ± 0.907 )were statistically up regulated compared with 0 hour (1.001 ± 0.284),(q =15.9481,21.7647,17.0099,P ＜ 0.01 ).MMP-1mRNA for 4,15,24 hours' stretch (6.420 ± 2.143,23.695 ± 2.221,20.169 ±2.794) were statistically up regulated compared with 0 hour ( 1.000 ±0.414),( q =9.3421,39.1178,33.0403,P ＜ 0.01 ).TIMP-1 mRNA for 4,15 hours' stretch (0.455 ± 0.370,0.481 ± 0.386)were statistically down regulated compared with 0 hour( 1.000 ± 0.425 ),( q =6.5265,6.3106,P ＜0.05).But for 24 hours'stretch,the mRNA expression( 0.883 ± 0.538 ) restored to the level of 0 hours.Conclusions The morphology,orientation and the synthesis function of the uterosacral ligament fibroblasts can be regulated by mechanical stress.Extracellular matrix remodeling may be adaptive changes due to the mechanical stress.