BACKGROUND:Smooth muscle cells and transitional epithelial cells were traditionally used to construct tissue-engineered bladder and to perform double-sided implantation of scaffold.However,double-sided implantation is difficult to perform,because smooth muscle cells are difficult to isolate or culture in vitro and passage is limited.OBJECTIVE:To verify the feasibility of tissue-engineered bladder reconstruction with bone marrow mesenchymal stem cells(BMSCs)and bladder acellular matrix(BAM).DESIGN:A basic empirical study.SETTING:Linbaixin Medical Research Center,Second Affiliated Hospital,Sun Yat-sen University.MATERIALS:Experiments were performed at the Linbaixin Medical Research Center,Second Affiliated Hospital,Sun Yat-sen University from March 2006 to Mav 2007.The laboratory was the Opening Laboratory of Hospital Affiliated to Health Department of China.One-month old SD rats of either sex,weighting 80-100 g were provided by Animal Experimental Center of Sun Yat-sen University.Fresh porcine bladders were offered by Animal Experimental Center of Southern Medical University.METHODS:Whole bone marrow culture and successive adherence method was used to culture rat BMSCs in vitro.Flow cytometry was employed to detect surface antigen.Eradicator washing method was applied to prepare porcine BAM and measure its purity and characteristies.Third passage of BMSCs were inoculated in BAM and cultured in a medium containing vascular endothelial growth factor(VEGF165)(25 ng/L)in vive and in vitro to test compatibility.Cells cultured alone were considered to be controls for the in vivo trial,and materials non-implanted with cells were considered to be controls for in vitro trial.Suitable microenvironment was simulated to induce the differentiation of BMSCs.Four weeks and eight weeks later,compound materials were respectively removed to perform tissue section test.Simultaneously,immunohistochemistry keratin staining was conducted to examine regeneration of epithelial cells.MAIN OUTCOME MEASURE:Biocompatibility of BMSCs and BAM.RESULTS:①BMSCs were cultured by whole bone marrow method.Flow cytometry demonstrated that third passage of cells were positive for CD29(99.43%).②BAM had good biological characteristics.Homogen matrix and byssoid collagen appeared under a microscope.Compatibility trials showed good compatibility of BMSCs and BAM and well-growth cells.③Four weeks later,histological section test confirmed inflammatory cell infiltration,closely-arranged collagen and elastic fiber.Immunohistochemistry keratin staining showed lamellar and discontinuous simple epithelium.Eight weeks later,no inflammatory cell infiltration was found,and closely-arranged collagen and elastic fiber were detected.Immunohistochemistry keratin staining showed lamellar and continuous multiple epitheliums.CONCLUSIoN:With good compatibility,BMSCs and BAM appear to be an ideal material for bladder tissue engineering.