Results of endoscopic subureteral collagen injection for reflux correction in pigs and dogs

Abstract

The efficacy of endoscopic correction of reflux with the use of Teflon has been proven, but there are safety concerns because of granuloma formation and particle migration. Using glutaraldehyde cross-linked (GAX-) bovine collagen as an alternate biomaterial, animal experiments were performed with 6 female pigs and 20 beagle dogs. Primary and experimentally-induced vesicoureteral reflux was treated by endoscopic injection of bovine GAX-collagen (Zyplast) submucosally at the ureteric orifice. Radiographic controls after 6, 8, or 12 months revealed successful reflux correction in 14 of 19 treated ureters of dogs. After the animals were killed, pathohistological evaluation demonstrated persistence of the collagen depot at the site of injection even after 12 months, although not in all cases, without inflammatory or foreign-body tissue reaction. No evidence of particle migration was found. Invasion of fibroblasts and fibrocytes into the collagen depot and capillary vessel formation appeared the same after the different time intervals, and there was no difference between the two animal species. The biocompatibility of purified bovine GAX-collagen makes it an alternative to Teflon for reflux correction.