Urethral reconstruction with tissue engineering and RNA interference techniques in rabbits

Objective: To investigate the feasibility of replacing urinary epithelial cells with oral keratinocytes and transforming growth factor β (TGF-β)1 siRNA transfected fibroblasts seeded on bladder acellular matrix graft (BAMG) to reconstruct urethra.

Methods: Autologous oral keratinocytes and TGF-β1 siRNA transfected fibroblasts were seeded onto BAMGs to obtain a tissue-engineered mucosa. The tissue-engineered mucosa was assessed using morphology and scanning electron microscopy. In 27 male rabbits, a ventral urethral mucosal defect was created. Urethroplasty was performed with autogenic oral keratinocyte and TGF-β1 siRNA transfected fibroblast-seeded BAMGs (9 rabbits, group 1), with autogenic oral keratinocyte-seeded BAMGs (9 rabbits, group 2) or with BAMGs with no cell seeding (9 rabbits, group 3). Retrograde urethrography and histological analyses were performed to evaluate the results of urethroplasty.

Results: In vitro, oral keratinocytes and TGF-β1 siRNA transfected fibroblasts had good biocompatibility with BAMGs. In vivo, the urethra kept a wide caliber in groups 1 and 2. Strictures were observed in group 3. Histologically, the retrieved urethra in group 3 showed fibrosis and inflammation during 6 months. Stratified epithelial layer regenerated in group 2, whereas there was no evidence of formation of capillary in the epithelial lower layer during the study period. Stratified epithelial layer and formation of capillary in the epithelial lower layer were evident after 6 months in group 1.

Conclusion: Our study suggested that oral keratinocytes and TGF-β1 siRNA transfected fibroblasts could be used as a source of seed cells for urethral tissue engineering.