Oxidative damage to human parametrial ligament fibroblasts induced by mechanical stress

The aim of the present study was to explore the underlying mechanisms of the roles of mechanical factors in the pathogenesis of pelvic organ prolapse (POP). The experiments were performed on fibroblasts derived from uterosacral ligaments and cardinal ligaments of patients who received total hysterectomy due to benign disease excluding POP. Fibroblasts were cultured after collagenase digestion and identified by morphological observation and immunocytochemical methods. A four-point bending device was used to subject fibroblasts at passage 4-6 to strains of 0, 1,333 mu (1 mm), 2,666 mu (2 mm) or 5,333 mu (4 mm) at a frequency of 0.1 Hz for 4 h. Intracellular reactive oxygen species (ROS) were quantified using the fluorescent probe 2',7'-dichlorodihydrofluorescein diacetate. Changes in the mitochondrial membrane potential were verified using the fluorescent dye JC-1, and apoptosis was detected using Annexin V/propidium iodide staining and flow cytometric analysis. Mechanical strain changed the morphology and adherence ability of parametrial ligament fibroblasts. Furthermore, the production of ROS was significantly increased and the mitochondrial membrane potential obviously declined with the enhancement of mechanical stress loading. In addition, the apoptotic rate of fibroblasts subjected to high mechanical strain was significantly increased compared with that in fibroblast under low-intensity strain. In conclusion, the present study showed that mechanical strain enhanced intracellular ROS levels, decreased the mitochondrial membrane potential and increased the apoptotic rate in human parametrial ligament fibroblasts, which may contribute to POP.