Hypothesis. Overflow urinary incontinence (OUI) often occurs as a complication after pelvic surgery. Our previous experiment found that bone marrow-derived stem cell lysate (BMSCL) improves neurogenic erectile dysfunction. In this study, we investigated the effectiveness of BMSCL in a model of OUI by bilateral accessory nerve injury (ACNI). 
Methods. Rat bone marrow-derived stem cells were collected, and BMSCL (lysate of 1×10⁶ cells/PBS) was prepared. Eight-week-old male Wistar-ST rats were divided into sham+PBS (sham, n=7), ACNI+PBS (ACNI, n=10), and ACNI+BMSCL (BMSCL, n=10) groups. Following surgery, PBS or BMSCL (100μl/body) was administered intravenously. Bladder function, bladder weight, and morphology were evaluated after one week. In addition, the response of carbachol (CCh) was assessed.
Results. While 7 of 10 rats in the ACNI group showed symptoms of OUI, only 3 of 10 rats in the BMSCL group presented symptoms of OUI. Bladder weight in the ACNI group was significantly larger than in the sham group (P<0.01), while bladder weight in the BMSCL group was significantly lower than in the ACNI group (P<0.01). Fibrotic area in the ACNI group was larger than in the sham group, while that in the BMSCL group was smaller than in the ACNI group. The maximum response to CCh in bladder specimens in the ACNI group was higher than that of sham group, while this was lower in the BMSCL group than in the ACNI group.
Conclusion.  BMSCL improved bladder function and morphology, suggesting that intravenous injection of BMSCL may be a useful treatment for neurogenic bladder dysfunction.