INVIVO ASSESSMENT OF NEOVASCULARIZATION AND INCORPORATION OF PROSTHETIC VASCULAR BIOGRAFTS

Neovascularization plays a major role in prosthetic vascular graft healing. New developments in manufacturing biomaterials have encouraged the use of biological and biosynthetic materials for both arterial replacement and bypass procedures. We have analyzed in vivo the process of neovascularization and incorporation of biolized bovine carotid artery (Solco P(R)), a biological material, and the composite of ovine collagen and polyester mesh (Omniflow(R)), a biosynthetic material. The synthetic fabric polytetrafluoroethylene (e-PTFE), which is widely used in cardiovascular surgery, served as control. Using the dorsal skinfold chamber of the Syrian golden hamster as site for implantation (n = 15), angiogenesis and neovascularization were analyzed quantitatively by means of intravital fluorescence microscopy. In each chamber a piece (approximately 1 mm2) of each of the three vascular grafts was implanted. Five days after implantation neovascularization was ascertained in 90% of the Omniflow(R) grafts, while only 40% of the PTFE and 20% of the Solco P(R) implants revealed new ingrowing microvessels. On day 10 the density of newly formed microvessels was significantly higher (p < 0.01) in Omniflow(R) grafts (263.5 +/- 24.1 cm-1) as compared to PTFE (134.2 +/- 20.8 cm-1) and Solco P(R) (153.2 +/- 32.O cm1). In addition, the biosynthetic composite revealed a larger extension of neovascularization into the perigraft tissue, and 12 days after implantation these grafts were most tightly incorporated. Failure of neovascularization of Solco P(R) was associated with remarkable fibrous collagen thickening, Superior neovascularization of Omniflow(R) might be due to the additional loose polyester mesh support of the material and potentially due to prevention of fibrous collagen thickening.