Physiologic properties of small intestine submucosa

Porcine small intestine submucosa (SiS) has been introduced as a bioprosthesis in herniorrhaphy. This study evaluates in vivo properties of SiS that would affect clinical use.

Twelve pigs underwent implantation of SiS (perforated and nonperforated) on the peritoneal surface. Gross characteristics were evaluated and random samples harvested for histological study at 2 (n = 6) and 8 (n = 6) weeks. Collagen deposition was determined by polarized microscopy. Neovascularity (percent area blood vessels, %A(bv)) was determined by immunohistochemical staining with a polyclonal CD-31 antibody.

Perforated SiS had a higher density of capillary ingrowth compared with nonperforated at both 2 (5.6%A(bv) versus 1.4%A(bv), P < 0.05) and 8 weeks (6.0%A(bv) versus 1.6%A(bv), P < 0.05). Compared with 2 weeks, 8-week SiS had a larger proportion of incorporation (25% versus 83%, P < 0.05) and new collagen deposition (50% versus 94%, P < 0.05). Significant contraction was observed in SiS 8 weeks after implantation (preimplant area 98 cm2 versus post-implant area 50 cm2, P < 0.05).

SiS incorporated well 8 weeks after implantation, with deposition of new collagen. Perforated SiS demonstrated a more rapid and greater amount of neovascularity. The degree of contraction suggests that larger areas of SiS should be selected for herniorrhaphy than would be necessary if synthetic materials were used.