摘要Objective To assess the effect of intra-sphincteric injections of human umbilical cord mesenchymal stem cells(HUMSCs) on leak point pressure (LPP) changes in an animal model of stress urinary incontinence (SUI).Meanwhile,to investigate in vivo MRI tracking HUMSCs in SUI rats using a clinically available paramagnetic contrast agent (Gd-DTPA) and commercially available effentence transfection reagents..Materials and Methods HUMSCs were dual labeled with Gd-DTPA and PKH26,the labeling efficiency and longevity of Gd-DTPA maintenance were measured and cell viability and proliferation were assessed.39 female Sprague-Dawley SUI rats.12 normal rats and 12 SUI rats received periurethral injection of PBS and 12 SUI rats were given periurethral injection of dual labeled HUMSCs.3 SUI rat sreceived periurethral injection of unlabeled HUMSCs.Six weeks after injection,LPP was undertaken in animals.All rats were sacrificed and frozen urethra sections were submitted to pathology and immunohistochemistry assessment.Results The labeling efficiency of Gd-DTPA was up to 80％,the labeling procedure did not influence cell viability and proliferation.The signal intensity on T1-weighted imaging and T1 values of labeled ceils were significantly higher than those of unlabeled cells.In vitro,differentiated HUMSCs expressed myosin heavy chain(MHC) and desmin,markers of striated muscles.In vivo,immunohistochemistry of rat urethras revealed dual labeled HUMSCs in situ and at the injection site.LPP was significantly improved in animals injected with HUMSCs.Atrophic urethras with implanted HUMSCs were positively stained for MHC and desmin.The distribution and migration of labeled cells could be tracked by MRI more than 14 days after transplantation.Conclusion HUMSCs have the ability to differentiate striated muscles,as demonstrated by MHC and desmin expression.Periurethral injection of HUMSCs in an animal model of SUI restored the damaged external urethral sphincter and significantly improved LPP.MRI can track Gd-DTPA-labled HUMSCs in an animal model of SUI in vivo.