Laminin-5-enriched extracellular matrix accelerates angiogenesis and neovascularization in association with ePTFE

The performance of biomedical implant devices is often limited by inappropriate tissue responses associated with synthetic materials used in device construction. Adverse healing responses, in particular the lack of an extensive vascular supply in the peri-implant tissue, are believed to lead to the ultimate failure of many of these medical devices. Accelerated formation of new blood vessels in the peri-implant tissue and within porous polymeric implants is hypothesized to improve the performance of such biomedical implant devices. The current study evaluated the use of cell-mediated, extracellular matrix modification of expanded polytetrafluoroethylene (ePTFE) to increase vessel growth in peri-implant tissue and within the pores of the implants. Discs of ePTFE were modified through cell-mediated matrix deposition using epithelial and endothelial cell lines with variable deposition of collagen types, fibronectin, and laminin types. Cell matrix-modified discs, Matrigel-coated discs, and nonmodified discs were implanted in both the adipose and subcutaneous tissues of the rat. Following a 5-week implant period, samples were removed and evaluated histologically and morphometrically for the presence of blood vessels in the peri-implant tissue and within the pores of the polymer as well as for the presence of activated macrophages and monocytes. A significantly increased presence of activated macrophages and monocytes was associated only with the samples modified with the matrix from a human microvessel endothelial cell line. Increased vessel density was identified in association with those ePTFE samples modified with either the 804-G, HaCaT, or II-4 cell matrices, all of which have extracellular matrices enriched in the protein laminin-5.