Characterization of the deposition of collagen fibers and lithogenic potential in bladder of rats submitted to a sugar cane biopolymer graft.

OBJECTIVES Suture materials are widely used in urology. The interaction of these materials with the extracellular matrix in the inflammatory process can be estimated by stereology of collagen fibers and the present study was designed to determine the behavior of the bladder tissue of rats to grafts of the biopolymer of sugar cane (BPCA), and the inflammation and intravesical stone formation compared to the polyglactin 910. MATERIALS AND METHODS 42 Wistar rats were divided in four groups: Group I (n = 10) rats submitted to bladder implantation of ~4-0 BPCA suture graft and euthanized at 4 weeks; Group II (n = 10) rats submitted to bladder implantation of 4-0 polyglactin 910 suture graft and euthanized at 4 weeks; Group III (n = 12) rats submitted to bladder implantation of ~4-0 BPCA suture graft and euthanized at 8 weeks; Group IV (n = 10) rats submitted to bladder implantation of 4-0 polyglactin 910 suture graft and euthanized at 8 weeks. Bladders collected at necropsy were analyzed for their weight and the presence of grafts and calculi. Sections were prepared for stereological analysis of collagen fibers. RESULTS The bladder weight was higher in group I, particularly in the presence of bladder stones. The presence of the graft was observed in 100 % (group I), 80 % (group II), 91.6 % (group III) and 30 % (group IV); polyglactin 910 showed an absorption of 70 % in this period. The stereological analysis showed a higher volume density of collagen fibers in group I versus other groups (p < 0.001). CONCLUSION The BPCA was a material with good integration into the bladder of rats; its absorption was slower than that of the polyglactin 910. The presence of urinary stones was lower in bladders with implantation of BPCA, particularly after 8 weeks. There was a greater initial inflammatory response to BPCA graft that was directly related to the increase in bladder weight and the presence of urinary stones, but that equalized the results of polyglactin 910 after 8 weeks.