Objective        To investigate regenerative and functional reconstruction effect of human cord blood mononuclear cells (HCMNCs) transplantation into the urethral sphincter of rats with stress urinary incontinence (SUI).       Methods        A female SD rat model of SUI was established by repeative vaginal distention  to simulate birth trauma. According to random number table method

forty virgin female SD rats were randomly divided into 2 groups

the sham-operation group (n=10) and experimental group (n=30). The rats in the experimental group were further divided 2 subgrou

ps (n=15)

that is

the transplantation group and the SUI group. HCMNCs were isolated by density gradient centrifugation

and labeled by 4

6-diamidine-2-pheny-lindole dihydrochloride (DAPI). After 7 days of second vaginal expansion

the transplatation group was injected into HCMNCs (approximately 2×10

6

cells) at proximal urethra

whereas the SUI group was injected into the same volume of PBS. The urodynamic indicators

retrograde urethral perfusion pressure (RUPP) and maximum bladder capacity (MBC) were measured and recorded in 7 and 14 d after transplantation. The proximal urethral tissues were collected in 7 d after transplantation

the cell shape and morphology

and fluorescent distribution were observed by HE staining

Masson staining and laser scanning confocal microscopy.       Results        A rat model of female SUI was established successfully through repeated vaginal distention. HCMNCs remained alive and distributed in the damaged urethral sphincter. Consequently

the transplantation group showed better repair compared to the SUI group in damaged urethral sphincter

and the continence function of urethral sphincter in SUI rat models was significantly improved.       Conclusion        HCMNCs can be successfully transplanted into urethral sphincter to improve urinary capacity of SUI rats

and the transplantation promotes the repair of urethral sphincter. Our results suggest HCMNCs transplantation may be an effective method to treat female stress urinary incontinence.