Rabbit Urethral Defect Repair With Human Amnion Extracellular Matrix

Background and Objective: Urethral defect,trauma and others whichcaused by congenital and acquired urethral disease still remains a challenge for most of urological surgeons. According to the past literatures, there are more than 300 operation methods for urethral repair and many materials have been used for urethral reconstruction ,such as artery ,vein ,appendix ,scrotum skin, bucca mucous coat ,blister ,uretero ,bladder mucous, cavum oris mucous and so on. But most of the methods are based on sacrificing normal tissues, so the effect is not ideal and in which there are high complications, such as fistula,stenosis and others .Besides, the source of autografts limits their clinical application.With the rapid development of life science, material science, physics and chemistry, a new intersect science named tissue engineering arises, which studies and makes biologic substitute to repair damaged tissues applying the principles of cell biology and engineering.Tissue engineering has been proposed as a strategy for urethral defect .In the study and research of urologic tissue engineering the support material is very important for tissue or organ's reconstruction.As support stuff, extracellular matrix has been paid more and more attenation recently. Extracellular matrix locate at epithele or under endothelial cells or around connective tissue , which can provide mechanical support and physical intensity for tissue even all organism.Further study showed that extracellular matrix not only can provide mechanical support for organism, but also has profound influence on cell reproduction, adhere, differentiation, development, diffuseness, migration, acesis anomaly, apoptosis etc . When the extracellular matrix was abstained, all cellular components were extracted and elastic and collagen fibers kept normal festure and structure. So extracellular matrix has ideal tissue compatibility ,but no immunity, which is the theorectical basis of this material can be used for tissue repair.As a kind of biological material, human amniotic membrane has been used in foundmental and clinical medicine for many years. With the development of modern biologic technique, human amnion extracellular matrix(HAECM) has become the focus of researching. Because of the ideal immunological compatibility, HAECM can be used as the support stuff for cell's adhere and growth.In this experiment, we want to use HAECM to repair rabbit urethral defect and seek an ideal material for urethral reconstruction.Methods: HAECM was obtained form health fresh human amniontic membraneby decellularization process. Then carefully observed it under interted microscope to confirm the cellular components were completely removed. 12 male rabbits were randomly devided into 2 groups. A, study group, including 9 rabbits ;B, control group, including 3 rabbits. In study group, a 1.0 cm segment of urethra was resected, and replaced by an HAECM of equal length and calibration .In control group ,after the urethral tissue were exposed ,cut in the middle and then stitched with 6-0 adsorbable suture. 8* silicone tubes were placed into two groups rabbit's urethra as supporting and urination. The first week after the operation, every rabbit wasinjectioned with penicillin 8×10~6u/d . 10 days after the operation, the silicone tubewas removed. Macrographical and histopathological examination of two groups were carried out at 4 weeks, 12 weeks, and 16 weeks. Results:1. Macrographically, HAECM is achromatic color and has elastic behavior. Histopathlological examinetion showes that the normal collagen fibers and structure were kept.2. All rabbits survived surgery .In study group ,1 had infection in the 7th day , infection was controled after treatments,but fistula occurred on it;l had fistula after the tube was removed. In control group all rabbits successfully recoveried.3. 4 weeks after the operation: Macrographical examination of the study group showed that the continuity of urethra was restorated, but not very smooth. Histopathological examination showed gradual regeneration over the HAECM and was epithelied. In control group, macrographical and histopathologicl examination showed the urethra was healed smoothly.4. 12 weeks after the operation: Macrographical examination of study group shows that the urethra are even , concordance ,continuous and smooth , approach to the control. Histopathologically, the urethral epithelial cell of study group arranged proximitly stabilized and regulaly, and a few urethral smooth muscle bundles appeared, but less than the control obviously.5. At 16 weeks: Histopathologically, the tissue hierarchy of study group approached to the control ,and the number of the urethral smooth muscles between both groups have no significant difference. But the study group's smooth muscles were obviously disorder by comparion of the control.Conclusion:HAECM tube can be used to repair a 1.0 cm segment of the rabbit urethral defect.