Urethral reconstruction with tissue-engineered human amniotic scaffold in rabbit urethral injury models.

Background: Mitigating urethral injury remains a great challenge for urologists due to lack of ideal biomaterials for urethroplasty. The application of amniotic membrane (AM) over other synthetic materials makes it a better potential source for urethral reconstruction. We separated the basement layer of AM to obtain denuded human amniotic scaffold (dHAS) and then inoculated primary rabbit urethral epithelial cells on the surface of dHAS to determine whether this strategy minimizes potential rejection and maximizes the biocompatibility of human AM. Material/Methods: After the successful acquisition of dHAS from AM, cell-seeded dHAS were prepared and characterized. Both cell-seeded dHAS and acellular dHAS were subcutaneously implanted. Immune responses were compared by histological evaluation and CD4(+) cell and CD8(+) cell infiltrations. Then they were applied as urethroplastic materials in the rabbit models of urethral injury to fully explore the feasibility and efficacy of tissue-engineered dHAS xenografts in urethral substitution application. Results: Mild inflammatory infiltration was observed in cell-seeded dHAS grafts, as revealed by fewer accumulations of CD4(+) cells and CD8(+) cells (or neutrophils or other immune cells). Urethral defects of rabbits in the urethroplastic group with dHAS implantation (n=6) were completely resolved in 1 month, while there were 1 infection and 1 fistula in the control group with acellular dHAS patches (n=6). Histopathological analysis revealed mild immune response in the cell-seeded dHAS group (P<0.05). Conclusions: Tissue-engineered dHAS minimizes potential rejection and maximizes the biocompatibility of AM, which makes it a potential ideal xenograft for urethral reconstruction.