ObjectiveTo explore the effects of myoblast formation around the urethra of stress urinary incontinence (SUI) rats after treated with bone marrow mesenchymal stem cells(BMSCs) or musclelike cells/calcium alginate composite gel injection therapy.MethodsIsolation,cultivation and identification of Sprague-Dawley rat bone marrow mesenchymal stem cell were performed.5-azacytidine was introduced to induce muscle-like cells.Calcium alginate gel was initially prepared by 2％ sodium alginate and 1％ calcium chloride solution at a volume ratio of 5∶1.Compounds of stem cells or muscle-like cells were mixed with gel,respectively,and were prepared for microinjection.SUI was produced in 72 6-week-old female Sprague-Dawley rats.The rats were then divided into 4 groups:Gel group,stem cell-gel group,muscle-like cell-gel group and mock control group.Each group was further divided into 3 groups.Submucosal injection of gel was performed at urethra and bladder neck.After preparation of cross sections of rat urinary tract at 4 weeks and 8 weeks after injection,HE staining,fluorescent tracing,staining of Desmin and α-skeletal muscle actin (α-SMA) were performed.OD values of positive rates were compared.ResultsAt 4 weeks and 8 weeks after injection in stem cell-gel group and muscle-like cell-gel group,growth of blood vessels gradually increased at gel edge,BMSCs and muscle-like cells gathered around the new blood vessels observed by fl(u)orescence tracer,muscle-like cells grew into elongated spindle-like cells.Desmin and α-SMA staining were positive in these groups,and the OD values in the stem cell-gel group and muscle-like cell-gel group was significantly higher than that from the gel only group and control group,but no difference was found between stem cell-gel group and muscle-like cell-gel group.ConclusionsCompound of BMSCs,muscle-like cells and calcium alginate composite gel has the potential to differentiate into muscle cells in the microenvironment of SUI rat model.In short term,the myoblast formation potential is the same whether the BMSCs was introduced into the micro-environment in vivo directly,or the BMSCs was implanted into microenvironment after the formation of the muscles cells induced by 5-azacytidine in vitro.