Neovascularization of Prosthetic Vascular Grafts. Quantitative Analysis of Angiogenesis and Microhemodynamics by Means of Intravital Microscopy

Abstract

Neovascularization of prosthetic vascular grafts seems to play an important role in the prevention of early graft failure due to infection of thrombotic occlusion. The process of angiogenesis and neovascularization was analyzed for three different prosthetic vascular grafts (PTFE, Dacron double microvelour and gelatin-coated Dacron double microvelour) in vivo by means of fluorescence microscopy. Under Nembutal anesthesia (50 mg/kg BW) Syrian golden hamsters were fitted with a dorsal skinfold chamber, which contains the cutaneous skeletal muscle as well as subcutaneous tissue, and allows for quantitative analysis of the microcirculation for a prolonged period of time. In each chamber one piece (1mm2) of all three vascular grafts was implanted. Five days after implantation neovascularization was ascertained in 9/11 (coated) and 8/11 (non-coated) Dacron grafts, while only 4/11 PTFE implants revealed new microvessels. On day 10 the density of newly-formed microvessels was significantly higher (p less than 0.001) in Dacron grafts (234.3 +/- 31.2 cm-1 and 238.9 +/- 41.3 cm-1 respectively) as compared to PTFE implants (154.9 +/- 30.4 cm-1). In addition, Dacron grafts revealed a larger neovascularization zone extending into the perigraft tissue. 12 days after implantation non-coated Dacron grafts were most tightly integrated into the perigraft tissue. The better neovascularization of Dacron might be due to the high porosity of the graft compared to low porous PTFE, which revealed insufficient neovascularization.