Urethral substitution using autologous lingual mucosal grafts: an experimental study

Objective To investigate the feasibility of urethral substitution using free lingual mucosa grafts (LMGs) in a dog model. Materials and Methods The study included 10 female mongrel dogs in which a 4 x 1 cm(2) section of urethral mucosa was excised. The defect was immediately repaired with a size-matched free LMG harvested from the inferior lateral surface of the tongue. A 12 F urethral catheter was kept inside the urethra for a mean of 7 days. At 3 months after the procedure, the patency of the urethra was assessed by both insertion of a 12 F catheter and by retrograde urethrography. Dogs were killed, the grafted areas excised, and evaluated by gross and histopathological examination. Results All dogs survived the procedure and there were no tongue complications. One of the 10 dogs developed a slight urethral stricture near the proximal anastomosis. The remaining nine dogs voided spontaneously with no difficulty. Retrograde urethrography showed that no strictures or fistulas had formed. The LMGs shortened by 9.5% after surgery, from a mean of 4 (0.13) to 3.62 (0.11) cm (statistically significant, P < 0.05). Histological examination showed that the LMGs were well-incorporated into the urethral walls and covered by a keratinized squamous epithelium. Neovascularization was evident beneath the grafts. Conclusions We successfully developed an dog model for free LMGs and showed the feasibility of this approach for urethral substitution.