Treatment of stress urinary incontinence with low-intensity extracorporeal shock wave therapy in a vaginal balloon dilation induced rat model

BACKGROUND: To investigate the outcomes and mechanisms of low-intensity extracorporeal shock wave therapy (Li-ESWT) on stress urinary incontinence (SUI) in a vaginal balloon dilation (VBD) rat model. METHODS: Thirty Sprague-Dawley rats were randomly grouped into normal controls, VBD only, and VBD with Li-ESWT. Li-ESWT was administered twice per week for 3 weeks. Afterward, all 30 rats were assessed with functional and histological studies. To explore the acute effect of Li-ESWT, another 25 rats, given intraperitoneal 5-ethynyl-2-deoxyuridine (EdU) at birth, were treated with Li-ESWT followed by assessment of vascular endothelial growth factor (VEGF) expression and endogenous progenitor cells distribution at 24 hours or 1 week after the last Li-ESWT therapy. Additionally, rat myoblast L6 cells were used for myotube formation assay in vitro. RESULTS: Functional analysis with leak-point pressure (LPP) testing showed that rats treated with Li-ESWT following VBD had significantly higher LPP relative to those receiving VBD only (44.8±3.2 versus 27.0±2.9 cmH(2)O, P<0.01). Histological examinations showed increased urethral sphincter regeneration in Li-ESWT group. The rats treated with Li-ESWT also had increased vascularity, which was confirmed by immunohistochemistry of rat endothelial cell antigen, while reverse-transcriptase polymerase chain reaction (RT-PCR) showed VEGF expression was significantly enhanced. Additionally, there were significantly increased EdU+ cells in Li-ESWT treated rats at 24 hours. In vitro, Li-ESWT promoted myotube formation from L6 cells. CONCLUSIONS: Li-ESWT ameliorated SUI by promoting angiogenesis, progenitor cell recruitment, and urethral sphincter regeneration in a rat model induced by VBD. Li-ESWT represents a potential novel non-invasive therapy for SUI.