Time-dependent variations in inflammation and scar formation of six different pubovaginal sling materials in the rabbit model.

OBJECTIVES: To provide pathologic evidence, using six different sling materials, of the findings from rabbit model studies demonstrating loss of tensile strength and stiffness in porcine and cadaveric sling materials.
METHODS: Ten rabbits randomized into two survival groups (6 and 12 weeks of age) each had human cadaveric fascia, porcine dermis, porcine small intestine submucosa, polypropylene mesh, and autologous fascia implanted on their anterior rectus fascia. At harvest, hematoxylin-eosin and immunohistochemical staining for CD3, CD20, and MIB-I were performed. A pathologist unaware of the content of the slides quantified the degree of inflammation and fibrosis of each.
RESULTS: Significant differences were found for inflammation (P = 0.016), eosinophil infiltrate (P = 0.035), and inflammatory rind (P = 0.027) at 12 weeks, with polypropylene mesh having the lowest degree. At 12 weeks, differences were found in the presence of fibrosis/scar formation (P = 0.010) and degree of fibrosis/scar (P = 0.009). Although polypropylene mesh, cadaveric fascia, and porcine dermis all demonstrated a high presence of fibrosis/scar, polypropylene mesh had the greatest overall degree of scar formation at 12 weeks.
CONCLUSIONS: The inflammation with the cadaveric fascia and porcine materials may cause rapid clinical deterioration compared with autologous fascia and polypropylene mesh. These data provide a possible explanation for prior biomechanical studies demonstrating variations in tensile strength and stiffness of the different materials. The fibrosis and scarring noted with polypropylene mesh may also contribute to a more lasting repair.