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BACKGROUND: Studies on substitute cells of bladder smooth muscle cells are in the early period at present. Mesenchymal stem cell transplantation is an ideal method. Human amniotic mesenchymal cells can differentiate into cardiomyocytes and nerve growth factor and promote local structure repair.
OBJECTIVE: To investigate the differentiation of human amniotic mesenchymal cells into smooth muscle cells following transplantation, and the effects on bladder muscle layer.
DESIGN, TIME AND SETTING: The cytology in vitro study was performed at the Japan Xinzhou University from October 2006 to April 2007.
MATERIALS: Human amnion was obtained from healthy full-term puerperal. A total of 18 clean female Sprague Dawley rats were randomly and equally assigned into normal bladder cell transplantation group, frostbite bladder control group, and frostbite bladder cell transplantation group.
METHODS: Amnion was cut and mixed in DMEM containing trypsin. Epithelial cells were removed prior to tissues were incubated in DMEM, supplemented with collagenase and DNA enzyme. Human amniotic mesenchymal cells were harvested for use. Posterior vertex of urinary bladder was frozen using a -70 ℃ iron rod in rats of the frostbite bladder control group and frostbite bladder cell transplantation group. Hematoma appeared at the frostbite region of the bladder three days later. 100 μL DMEM was injected into the hematoma of the rats of the frostbite bladder control group, while an equal volume of human amniotic mesenchymal cell suspension (105 cells) was injected into the hematoma of the rats of the frostbite bladder cell transplantation group. Human amniotic mesenchymal cell suspension was implanted into the normal rat bladder in the normal bladder cell transplantation group. After three weeks, the bladder tissue including partial urethra was used for bladder sample preparation.
MAIN OUTCOME MEASURES: Bladder smooth muscle repair was observed using hematoxylin-eosin staining. The differentiation of human amniotic mesenchymal cells in the wall of urinary bladder was detected using fluorescence immunohistochemistry.
RESULTS: Compared with the normal bladder cell transplantation group, normal wall structure of urinary bladder, few fibrosis and good proliferation of smooth muscle cells were detected in the frostbite bladder cell transplantation group, while the wall of urinary bladder was slowly repaired, and disorder muscle structure, fibrosis, scar-like shape, and inflammatory cells were found in the frostbite bladder control group. Three weeks later, human amniotic mesenchymal cells were not seen in the normal bladder tissue. A large number of human amniotic mesenchymal cells was lived and some of them had differentiated into the smooth muscle cells in the frostbite bladder cell transplantation group.
CONCLUSION: Human amniotic mesenchymal cells had the potential to differentiate into bladder smooth muscle cells and promoted self-repair of the wall of urinary bladder. |