Early tissue reactions in the rat bladder wall after contact with three different synthetic mesh materials

To investigate bladder tissue reactions to three types of implanted mesh material, i.e. polypropylene, polyglactin and polypropylene-polyglactin combined.

Forty-eight adult female Wistar albino rats were randomized to four equal groups, i.e. group 1 (sham-operated controls), group 2 (polypropylene mesh), group 3 (polyglactin mesh) and group 4 (polypropylene-polyglactin mesh). A laparotomy incision was made to access the bladder and fix a 0.5 x 1 cm piece of mesh directly on the bladder wall. Each group was randomly divided into two subgroups of six animals, killed at 7 and 14 days after mesh implantation, respectively, to study mesh and tissue features with time. Bladders were harvested for histological and immunohistochemical investigation. Microvessels that developed around the mesh were detected with the avidin-biotin peroxidase system, using antibody to Factor VIII-related antigen as an endothelial marker. Vessels were counted in the most intensely stained area of one section from each animal's bladder.

Compared with the other groups, group 4 had more inflammatory reaction at 7 days but the tissue reactions to all mesh materials were similar at 14 days; the mesh penetrated the bladder muscularis propria at 14 days in all six rats in group 2, in one in group 3, and two in group 4. Group 4 tended to have a greater microvessel density at 14 than at 7 days. In contrast, groups 2 and 3 had lower microvessel densities at 14 than at 7 days.

The rat bladder wall had a similar early response to all three types of mesh materials. Penetration was more marked with polypropylene mesh than with the other materials. This nonabsorbable material persists in tissue and is currently widely used for clinical applications. These results for penetration suggest that the use of polypropylene mesh risks serious postoperative complications, e.g. urethral tissue erosion.