[Comparison of three composite patches for repair of abdominal wall defect in rats under contaminated environment]

To observe the anti-adhesion and repair effect of 3 composite patches which composed of polylactide-co-caprolactone (PLC), hyaluronic acid (HA), collagen, and polypropylene (PP) mesh repairing abdominal wall defect in rats under contaminated environment, and to investigate the characteristics of 3 composite patches and the feasibility of one-stage repair.

Ninety-three adult male Wistar rats (weighing 150-250 g) were randomly divided into 3 groups (n = 31): PP/PLC composite patches (group A), PP/HA/PLC composite patches (group B), and PP/collagen/PLC composite patches (group C). One rat was selected from each group to prepare the contaminated homogenate of the small intestine. The abdominal wall defect models (1 cm in diameter) were established in other rats, and the defects were repaired with 3 composite patches (1.5 cm in diameter) according to grouping method. At 30, 60, and 90 days postoperatively, the adhesions was observed, and the patch and adjacent tissue was harvested for histological observation.

Six rats died at 10-70 days postoperatively (2 in group A, 3 in group B, and 1 in group C). No wound infection, intestinal obstruction, or hernia occurred in 3 groups. Adhesion was observed between abdominal viscera and the patch, especially intestine, epiploon, and liver. According to the modified Katada criteria, no significant difference in the adhesion score was found among 3 groups at 30 and 60 days (P > 0.05); the adhesion score was significantly lower in group C than in groups A and B at 90 days (P < 0.05). The histological results showed that inflammatory cell infiltration, fibroblasts, secreted collagen, and the residual absorbable material were observed around the patch at 30 days in 3 groups. Decreased inflammatory cell infiltration, increased fibroblasts and residual PLC were observed at 60 days in 3 groups. At 90 days, the fibroblasts became increasingly mature, collagen deposited, the mesothelium formed gradually, and the residual PLC decreased.

In contaminated environment, PP/collagen/PLC composite patch is superior to PP/PLC and PP/HA/ PLC composite patches in aspect of abdominal adhesion and inflammatory reaction, and it is more applicable to one-stage repair of rat abdominal wall defect. But it is necessary to further study in the long-term efficacy and the security of the composite patch.