Reconstruction Of Rabbit Ureteric Defect With Human Amnion

[Background and objective]The reconstruction of serious ureteric defection is always one of greatest challenges for clinical urologists.Many tissues or organs has been used to repair ureteric defect,such as appendix,omntum,allo-extracellular matrix,etc.These methods are complicated and macro-invasive at the cost of normal tissues;moreover,their long-term effects are skeptical and complications occur frequently.Due to the rapid development of life science,material sciences and their related sciences,a new crossing subject-tissue engineering appeared in 1980's.and has showed a brand-new outlet for the reconstruction of urologic system.In the field of tissue engineering,ideal scaffold materials play a key role in the rebuilding engineering tissues.Human amnion has been used widely in the ophthalmology as a alternative graft.Human arrmion is a natural biologic material and shows weak antigenicity for rarely inducing allo-graft rejection as well as other advantages,for example,low cost and abundant source obtained easily,etc. Therefore we study the effects and potential utilizations by using fresh intact human amnion to reconstruct rabbit ureteric defect.[Methods]Fresh amnions were cleaned with saline(4℃)several times and then clipped to pieces 4 cm-5 cm in length and 0.5 cm in width when they were dissected from abdominal delivery pregnant women's placentas.These arnniotic patches were sutured continuously with 7-0 silk threads in a shape like muff by utilizing epidural tubes(0.1 cm in diameter)as a stent.Under intravenous general anesthesia,left upper and middle part of rabbit ureter was mobilized through a flank incision.When 4 cm-long section of ureter was excised at a 2 cm distance to ureteropelvic junction and then the proximal end and distal end were bridged with muff-like human amnion by using end to end anastomosis. Anti-inflammatory treatment lasted 1-2 weeks.36 rabbit models were divided medially into group A and group B.Group A was raised 1 month and group B was breed 3 month after operation.At the end of study,all the rabbits were killed by anesthesia.Amnion-ureter were sliced through abdominal incision and then examined with pathologic method or immunohistochemistry in which the expression ofα-actin in smooth muscle cells and CK_AE1/AE3in transitional epithelial cell were checked.[Results]Of 36 rabbit models,6 in group Aand 8 in group B died from infection.In 12 survival rabbits in group A 1 month after allograft transplantation,soft amnion-ureters were 4 cm in length and showed thick ureteric wall and smooth ureteric lumina without any contracture;examined through the optical microscope,transitional epithelial cells covered throughout the inner wall and smooth muscle cells appeared sparsely in a mussy configuration;checked with immunohistochemistry,CK_AE1/AE3staining was positive butα-actin staining was very weak.In 10 survival rabbits in group B 3 month after transplantation,amnion-ureters were enclosed by their peripheral tissue and showed rich blood vessels and normal ureteric lumina without significant contracture;examined through the optical microscope,there was a well-arranged transitional epithelial layer and smooth muscular layer,checked with immunohistochemistry,CK_AE1/AE3staining andα-actin staining were all strong.[Conclusion]Engineering rabbit ureters could keep the channel function without clear constructure and necrosis and showed a normal ureteric mucous and muscular layer while human amnion was used to reconstructed serious ureteric defect(over 4 cm in length)as a stent.So fresh intact human amniotic membrane maybe an ideal engineering material for repairing ureteric defect.