BACKGROUND: Fibrosis of the connective tissue in the vaginal wall predominates in pelvic organ prolapse (POP), which is characterized by excessive fibroblast-to-myofibroblast differentiation and abnormal deposition of the extracellular matrix (ECM). Our study aimed to investigate the effect of ECM stiffness on vaginal fibroblasts and to explore the role of methyltransferase 3 (METTL3) in the development of POP. METHODS: Polyacrylamide hydrogels were applied to create an ECM microenvironment with variable stiffness to evaluate the effects of ECM stiffness on the proliferation, differentiation, and expression of ECM components in vaginal fibroblasts. METTL3 small interfering RNA and an overexpression vector were transfected into vaginal fibroblasts to evaluate the effects of METTL3 silencing and overexpression on matrix stiffness-induced vaginal fibroblast-to-myofibroblast differentiation and abnormal modulation of the ECM. Both procedures were detected by 5-ethynyl-2'-deoxyuridine (EdU) staining, Western blotting (WB), quantitative real-time polymerase chain reaction (RT-qPCR), and immunofluorescence (IF). RESULTS: Vaginal fibroblasts from POP patients exhibited increased proliferation ability, increased expression of α-smooth muscle actin (α-SMA), decreased expression of collagen I/III, and significantly decreased expression of tissue inhibitors of matrix metalloproteinases (TIMPs) in the stiff matrix ( P <0.05). Compared with those from non-POP patients, vaginal wall tissues from POP patients demonstrated a significant increase in METTL3 content ( P <0.05). However, silencing METTL3 expression in vaginal fibroblasts with high ECM stiffness resulted in decreased proliferation ability, decreased α-SMA expression, an increased ratio of collagen I/III, and increased TIMP1 and TIMP2 expression. Conversely, METTL3 overexpression significantly promoted the process of increased proliferation ability, increased α-SMA expression, decreased ratio of collagen I/III and decreased TIMP1 and TIMP2 expression in the soft matrix ( P <0.05). CONCLUSIONS Elevated ECM stiffness can promote excessive proliferation, differentiation, and abnormal ECM modulation, and the expression of METTL3 plays an important role in alleviating or aggravating matrix stiffness-induced vaginal fibroblast-to-myofibroblast differentiation and abnormal ECM modulation.
Humans ; Female ; Extracellular Matrix/metabolism* ; Cell Differentiation/genetics* ; Methyltransferases/metabolism* ; Pelvic Organ Prolapse/pathology* ; Fibroblasts/metabolism* ; Myofibroblasts/metabolism* ; Vagina/metabolism* ; Cell Proliferation/physiology* ; Cells, Cultured ; Middle Aged

Objective:To explore the surgical method and therapeutic effect of repairing soft tissue defect of digit-tip with single subcutaneous pedicle V-Y advancing flap combined with skin grafting.Methods:From August 2013 to December 2020, 25 soft tissue defects of digit-tip were repaired by a single subcutaneous pedicle V-Y advancing flap combined with pedicle skin grafting. The area of the defects was 0.8 cm× 0.8 cm to 1.6 cm× 1.4 cm. The flaps were harvested from palm or lateral side of the wound and the area of flap was 0.5 cm×1.0 cm to 0.8 cm×2.5 cm. In order to make the flap transfer to a further distance, the subcutaneous fibre connection of the flap was cut-off during the operation. At the same time, cut off 1 side of subcutaneous pedicle. Finally, the advanced distance of the flap reached 0.5-1.2 cm. After the flap harvested, the medium thickness skin was removed for graft to close the donor site from the wrist striations. After the surgery, follow-up visits were conducted regularly by outpatient clinic, or via telephone or WeChat review or by home visit. Throughout the follow-up, the flap appearance, sensation and recovery of the function of digital joint were observed, together with the patient satisfaction. Results:After the surgery, the postoperative follow-up lasted for 4 months to 8 years. All 25 flaps and skin grafts were survived in first stage wound healing. The flaps and skin grafting areas had excellent texture. The fingerprint had been reconstructed with good appearance. The TPD was 4-9 mm, the functions of digital joint recovered well, and there was no complain about a discomfort at the donor site. According to the evaluation standard of Michigan hand function questionnaire, all 25 patients were very satisfied with the overall appearance and function of the hand. According to Total Angle of Motion (TAM) evaluation standard, finger mobility was excellent in all 25 patients.Conclusion:Subcutaneous V-Y advancing flap combined with skin grafting is an ideal method for repairing soft tissue defect of digit-tip. The surgery characterises a simple flap cutting, less traumatic damage, long advancing distance of flap and good repair effect.