Feasibility of repairing urethral defects using human acellular amniotic membrane in rabbits / 中国组织工程研究

ABSTRACT

BACKGROUND: Acellular amniotic membrane used widely in treating ocular surface disease as well as extensive burn wounds due to its low antigenicity and excellent histocompatibility. However, it is poorly understood whether it can be used in repairing urethral defects.OBJECTIVE: To evaluate role and the feasibility of human acellular amniotic membrane (HAAM) in the rabbit urethral reconstruction.DESIGN, TIME AND SETTING: The randomized control experiment of animals was performed at the Laboratory Center of Guangxi Medical University between April and June 2007.MATERIALS: Thirty-two New Zealand rabbits were supplied by animal center of Guangxi Medical University. The human HAAM was obtained from Department of Obstetrics, First Affiliated Hospital of Guangxi Medical University.METHODS: HAAM was prepared by detergent-enzymatic approach. Firstly, the fresh amniotic membrane was protected with cross linking of 1% formaldehyde- 0.2% glutaral, digested with 0.125% trypsogen- 0.05 mol/L EDTA, followed by washing with 0.5% Triton X-100. Totally 32 New Zealand male rabbits were assigned into 3 groups: experimental group (n=12), control group (n=12) and sham operation group (n=8). Rabbits were prepared for urethral defects models in the experimental and control groups, which were repaired with HAAM or anastomosised directly. There was no urethral operation in the sham operation group.MAIN OUTCOME MEASURES: The growth of epithelial cells and smooth muscle cells, as well as inflammatory cell infiltration was observed by histopathologic examination at days 10, 21 and 42 after operation. The urethral pressure changes and urinary bladder was examined by retrograde urethrography at day 42 after operation.RESULTS: ①The prepared HAAM was translucent, there was no residual cells or fragments. ②The pathological section examination showed that in the experimental group, some epithelial cells has grown without acute rejection at day 10 after operation, and several layers of urothelium covered HAAM at day 21 with reduced inflammatory cell infiltration. At day 42, a sprinkle of smooth muscle grew in HAAM with few inflammatory cells. Urodynamic studies indicated that there were no significant difference among 3 groups in the bladder volume, maximum urethral pressure and minimum urethral pressure (P > 0.05). The weight of bladder had obvious difference between the sham operation and control groups (P < 0.05).CONCLUSION: HAAM is an ideal biomaterial with well histocompatibility, biocompatibility and low antigenicity. HAAM is a good choice for urethral reconstruction.