Introduction: Treatments of ureteral defects or strictures due to disease or trauma require reconstruction by urological surgery. However, those surgeries have some limitations, such as reoperation, or depending on ureteral length. Tissue engineering techniques would provide novel approaches to avoid the limitations. In this study, we fabricated bilayered autologous adipose-derived mesenchymal cell (AMC)-gelatin sheets and transplanted them into rabbits to replace surgically excised ureteral segments. Methods: AMCs harvested from abdominal adipose tissues of female New Zealand White rabbits were cultured on collagen-coated dishes and labeled with a red fluorescent dye, PKH26, for later identification. Monolayers of AMCs that were cultured on temperature-responsive dishes were harvested by a gelatin hydrogel sheet. Two AMC-gelatin sheets were then overlaid together with the cell sides juxtaposed, forming a bilayered AMC-gelatin sheet. Following each partial ureterectomy of approximately 1 cm, the bilayered autologous AMC-gelatin sheet was transplanted, joining the proximal and distal ends of the remaining the ureter (experimental group; n=9). Control animals were conducted with a bilayered acellular-gelatin sheet (control group; n=9). Results: At 4 and 8 weeks after transplantation, the proximal regions of ureters of control groups exhibited flexures and dilations compared with experimental groups. Both the control and experimental reconstructed ureteral walls had smooth muscle layers; however, those in the experimental reconstructed ureteral walls were significantly thicker and better organized than those in the control groups. In addition, the lumina of the 8-week reconstructed ureteral tissues in experimental groups did not show histological strictures as seen in the control ureters. Some AMCs differentiated into smooth muscle marker-positive cells. The experimental ureteral walls contained smooth muscle cells derived from the PKH26-labeled AMCs and others that were derived through migration and differentiation of cells from the remaining proximal and distal ends of the original ureter. Conclusions: These results indicated that the bilayered AMC-gelatin sheets could replace and/or reconstruct ureter tissues. SOURCE OF Funding: None.
