Repair of long ureteral defects often requires long graft tissues and extensive surgery. This is associated with complications, including a lack of suitable tissue and graft site morbidity. Tissue engineering may provide an attractive alternative to the autologous graft tissues. In this study, ureteral repair using (preimplanted) tubular collagen-Vicryl templates was evaluated in a new goat model. Tubular templates were prepared from tubularized Vicryl meshes and 0.7% type-I collagen (length = 6 cm, inner diameter = 6 mm, wall thickness = 3 mm). In total, twelve goats were used and evaluated after 3 months. Eight goats were implanted with the collagen-Vicryl templates and in four goats the templates were first preimplanted in the subcutis and subsequently used as ureteral graft. Template implantation was successful in 92% of the goats(11/12). During follow-up, 82% of the animals (9/11) survived without signs of discomfort. Two animals were sacrificed prematurely due to kidney perforation by the stent and urine leakage. Two other animals presented with stenosis of the neoureter due to stent migration. After preimplantation, the templates were remodeled mostly to autologous tissue with similar mechanical characteristics as the native ureter. Goats grafted with preimplanted templates presented with predominantly healthy kidneys, whereas the goats grafted with the collagen-Vicryl templates presented with fibrotic and inflamed regions in the kidneys. The use of preimplanted tissue templates showed favorable results compared with direct functional implantation of the templates. Partial remodeling toward autologous tissue and similar mechanical characteristics likely improved the integration in the ureteral tissue. Preimplantation of tissue-engineered templates should therefore be considered when two-stage procedures using a nephrostomy catheter are indicated or when planning allows for additional time to treatment.
Keywords: collagen; large animal model; preimplantation; scaffold; tissue engineering; ureter reconstruction.