Construction of bladder tissue-engineered grafts by urothelium-induced bone marrow mesenchymal stem cells and bladder acellular matrix / 中国组织工程研究

ABSTRACT

BACKGROUND:Urothelial cells are important seeding cells for urinary tissue engineering, but they are difficult to proliferate in vitro. Several studies have shown that bone marrow mesenchymal stem cells can differentiate into urothelial cells, but how these cells functions in vivo in epithelium generation after implantation, and the application of these cells in tissue engineering, are rarely studied. OBJECTIVE:To explore the isolation and proliferation of rabbit bone marrow mesenchymal stem cells that are induced into urothelial cells in combination with rabbit bladder acellular matrix to construct tissue-engineered grafts, and to assess the effect of the induced cells as seeding cells. METHODS:Twelve 8-week-old male New Zealand white rabbits were chosen to obtain bone marrow samples through tibia puncture, and to isolate bone marrow mesenchymal stem cells by density gradient centrifugation. Then the fourth or fifth generation of bone marrow mesenchymal stem cells were cultured in conditioned medium for 2 weeks, and then identified by PCR and immunofluorescence. After that, the induced cells were seeded on rabbit bladder acellular matrix to construct tissue-engineered grafts for bladder repairing. Another 12 rabbits served as control group, and urothelial cells combined with bladder acellular matrix was used for bladder repairing. RESULTS AND CONCLUSION:Bone marrow mesenchymal stem cells were successful y cultured and proliferated in vitro. After induction, PCR detection suggested that stem cellmarker (CD44) expression decreased, and epithelial cellmarker (UP1a) expression increased in the induced cells. Immunofluorescence staining demonstrated that the induced cells rather than bone marrow mesenchymal stem cells were positive for specific urothelial marker, UP1a. A stable continuous epithelial layer was observed on tissue-engineered grafts constructed by induced cells after 2 weeks, similar to the grafts built by urothelial cells. Induced bone marrow mesenchymal stem cells can differentiate into urothelial cells that can be used as seeding cells for urinary tissue engineering, which may be another choice out of urothelial cells.