QUANTITATIVE INVIVO ASSESSMENT OF THE TISSUE-RESPONSE TO DERMAL SHEEPCOLLAGEN IN ABDOMINAL-WALL DEFECTS

We quantified the tissue response, tissue organization and patency of biodegradable patches for the repair of abdominal wall defects. We use d dermal sheep collagen, cross-linked with hexamethylenediisocyanate i n a model. The collagen patches were implanted either untreated or pla sma polymerized with tetrafluoroethylene (TFE), to improve the propert ies of the patch for bowel adhesion and rate of degradation. The impla nts with surrounding tissue were retrieved after 3 d, 1, 2, 4, 6 and 8 wk, then sectioned and stained specifically for macrophages, neutroph ils, T-lymphocytes and endothelium. Only macrophages and neutrophils w ere observed in the implant and surrounding tissue, with different ant igen expression in the macrophages. This was found to be dependent on whether the macrophages were found within the implant or in the surrou nding tissue. The neutrophils and macrophages were assessed using imag e analysis techniques to quantify the tissue responses to treated and untreated collagen, enabling comparison of the respective tissue respo nses. No significant differences were found between the two forms of t his collagen. Infection played a key role in the severity of the tissu e response around both types of implants, resulting in large variation s in cell counts at each time period. Treating the collagen with TFE d id not significantly improve its performance in this application.