Acellular collagen matrix as a possible "off the shelf" biomaterial for urethral repair

Objectives. To determine whether a naturally derived collagen-based tissue substitute developed for urethral reconstruction would be suitable for uret hral repair in an animal model. Several urethral conditions often require n ongenital tissues for reconstruction, such as skin grafts or mucosal grafts from the bladder or buccal regions. However, the use of these tissues for urethroplasty may be associated with additional procedures for graft retrie val, prolonged hospitalization, and morbidity. Methods. A ventral urethral defect was created in 10 male rabbits. The acel lular collagen matrix, obtained and processed from porcine bladder submucos a, was trimmed and used to replace the urethral defect in an onlay fashion. Serial urethrography was performed pre- and postoperatively at 0.5, 1, 2, 3, and 6 months. The animals were sacrificed 0.5, 1, 2, 3, and 6 months aft er surgery. The retrieved implants were analyzed grossly, histologically, a nd with immunocytochemistry. Results. All animals survived until being sacrificed without any noticeable voiding dysfunction. Serial urethrograms confirmed the maintenance of a wi de urethral caliber without any signs of strictures. Cross examination at r etrieval showed normally appearing tissue without any evidence of fibrosis. Histologically, the implanted matrices contained host cell infiltration an d generous angiogenesis by 2 weeks after surgery. The presence of a conflue nt transitional cell layer was confirmed by immunocytochemical analyses usi ng pancytokeratin antibodies. Anti-alpha actin antibodies demonstrated the migration of unorganized muscle fiber bundles 2 months after implantation a nd organized muscle bundles 6 months after implantation. Conclusions. The acellular collagen matrix appears to be a useful material for urethral repair in the rabbit. The matrix can be processed easily, has good characteristics for tissue handling and urethral function, and has the advantage of being an "off the shelf" material. (C) 1999, Elsevier Science Inc.