Reconstruction of rabbit urethra using urethral extracellular matrix

BACKGROUND: Urethral reconstruction for both congenital and acquired etiologies remains a challenge for most urologic surgeons. Tissue engineering has been proposed as a strategy for urethral reconstruction. The purpose of this study was to determine whether a naturally derived extracellular matrix substitute developed for urethral reconstruction would be suitable for urethral repair in an animal model. METHODS: A urethral segmental defect was created in 20 male rabbits. The urethral extracellular matrix, obtained and processed from rabbit urethral tissue, was trimmed and transplanted to repair the urethral defect. Then, the regenerated segment was studied histologically by haematoxylin-eosin staining and Van Gieson staining at 10 days, 3 weeks, 6 weeks, and 24 weeks postoperation. Retrograde urethrography was used to evaluate the function of the regenerated urethras of 4 rabbits 10 and 24 weeks after the operation. The urodynamics of 4 rabbits from the experimental group and control group I were assessed and compared. In addition, 4 experimental group rabbits were examined by a urethroscope 24 weeks after the operation. RESULTS: At 10 days after operation, epithelial cells had migrated from each side, and small vessels were observed in the extracellular matrix. The matrix and adjacent areas of the host tissue were infiltrated with inflammatory cells. The epithelium covered the extracellular matrix fully at 3 weeks postoperation. Well-formed smooth-muscle cells were first confirmed after 6 weeks, at which point the inflammatory cells had disappeared. At 24 weeks postoperation, the regenerated tissue was equivalent to the normal urethra. Urethrography and urodynamic evaluations showed that there was no difference between normal tissue and regenerated tissue. CONCLUSIONS: Urethral extracellular matrix appears to be a useful material for urethral repair in rabbits. The matrix can be processed easily and has good characteristics for tissue handling and urethral function.