Anti-inflammatory and anti-bacterial effect of covalently attached biomembrane-mimic polymer grafts on Gore-Tex implants

Abstract

Introduction: Expanded polytetrafluoroethylene (ePTFE), also known as Gore-Tex, is widely used as an implantable biomaterial in biomedical applications owing to its favorable mechanical properties and biochemical inertness. However, infection and inflammation are two major complications with ePTFE implantations. To minimize these complications, i covalently grafted a biomembrane-mimic polymer, poly(2-methacryloyloxylethyl phosphorylcholine) (PMPC), by partial defluorination followed by UV-induced polymerization with cross-linkers on the ePTFE surface. The aim of this study is to evaluate the effects of PMPC grafting on ePTFE. Methods: Water contact angle, X-ray photoelectron spectroscopy, scanning electron microscopy and universal test machine analysis were measured to evaluate surface modification of PMPC grafted ePTFE plates. In vitro, for the evaluation of anti-inflammatory response, protein adsorption, fibroblast adhesion and bacterial attachment test were performed. In vivo, thirty-four female Sprague-Dawley rats were implanted with both non-grafted ePTFE and PMPC grafted ePTFE plates on the each side of back. At each time point of 24 hour and 72 hour, 8 rats were sacrificed and at 4 and 12 weeks, 9 rats were sacrificed respectively. Results: PMPC grafting greatly reduced serum protein adsorption as well as fibroblast adhesion on the ePTFE surface. Moreover, the PMPC-grafted ePTFE surface exhibited a dramatic inhibition of the adhesion and growth of Staphylococcus aureus, a typical pathogenic bacterium in ePTFE implantation, in the porous network. Based on an analysis of immune cells and inflammation-related factors, i.e. transforming growth factor-beta(TGF-beta) and myeloperoxidase (MPO) were significantly reduced in PMPC grafted ePTFE compare to non-grafted ePTFE. Conclusions: I confirmed that inflammation was efficiently alleviated in tissues around PMPC-grafted ePTFE plates implanted in the backs of rats. Covalent PMPC may be an effective strategy to promote anti-inflammatory and anti-bacterial functions in ePTFE implants and to reduce side effects in biomedical applications of ePTFE.