Histological response to injected gluteraldehyde cross-linked bovine collagen based implant in a rat model.

Background: The aim of present study is to investigate the short and long term histopathological alterations caused by submucosal injection of gluteraldehyde cross-linked bovine collagen based on an experimental rat model.

Methods: Sixty Sprague-Dawley rats were assigned into two groups as group I and II each containing 30 rats. 0.1 ml of saline solution and 0.1 ml of gluteraldehyde cross-linked bovine collagen were injected into the submucosa of bladder of first (control) and second groups, respectively. Both group I and II were further subdivided into 3 other groups as Group IA, IB, IC and Group IIA, IIB, IIC according to the sacrification period. Group IA and IIA, IB and IIB, IC and IIC rats (10 rats for each group) were sacrificed 3, 6, and 12 months after surgical procedure, respectively. Two slides prepared from injection site of the bladder were evaluated completely for each rat by being unaware of the groups and at random by two independent senior pathologists to determine the fibroblast invasion, collagen formation, capillary ingrowth and inflammatory reaction. Additionally, randomized brain sections from each rat were also examined to detect migration of the injection material. The measurements were made using an ocular micrometer at x10 magnification. The results were assessed using t-tests for paired and independent samples, with p < 0.05 considered to indicate significant differences; all values were presented as the mean (SD).

Results: Migration to the brain was not detected in any group. Significant histopathological changes in the gluteraldehyde cross-linked bovine collagen injected groups were fibroblast invasion in 93.3%, collagen formation in 73.3%, capillary ingrowth in 46.6%, inflamatory reaction in 20%.

Conclusion: We emphasize that the usage of gluteraldehyde cross-linked bovine collagen in children appears to be safe for endoscopic treatment of vesicoureteral reflux.