Angiogenesis and neovascularization associated with extracellular matrix-modified porous implants

Therapies directed toward stimulation of angiogenesis seek to accelerate the development of new blood vessels in tissues rendered dysfunctional because of an insufficient microvascular supply. The goal of the current study was the stimulation of an angiogenic response around and within porous biomedical implants, such as vascular grafts, constructed from a base polymer composed of expanded polytetrafluoroethylene (ePTFE). Similar to many biomaterials, ePTFE does not elicit a significant angiogenic response and the porous interstices of this material remain avascular after implantation. Studies were performed to evaluate the ability of a tumorigenic cell line, the 804-G rat kidney cell to secrete an angiogenic extracellular matrix on and within the porous structures of ePTFE. A rat model was used to evaluate and compare implant-associated healing responses between nonmodified materials and extracellular matrix-modified ePTFE. Results demonstrated that, in contrast to untreated ePTFE, the matrix-modified ePTFE stimulated both angiogenesis in implant-associated tissue and neovascularization of the pores within the ePTFE interstices. Deposition of an insoluble matrix stimulates an angiogenic response and has a potential application for the improvement of medical device function.