Gene Therapy by AdenovirusMediated Vascular Endothelial Growth Factor and Angiopoietin1 Promotes Perfusion of Muscle Flaps

An experimental study was conducted to investigate the potential use of intravascular gene therapy with adenovirusmediated Ad vascular endothelial growth factor VEGF or angiopoietinl Ang1 for the enhancement of muscle flap perfusion and to evaluate the effect of therapy on microcirculatory hemodynamics and microvascular permeability in vivo by using a cremaster muscle flap model in the rat. The cremaster tube flap was left intact after isolation of the pudoepigastric pedicle. A total of 90 male SpragueDawley rats were divided into five groups of 18 each, according to the type of intraarterial treatment. Control flaps received phosphatebuffered saline. Group 2 the control gene encoding green fluorescent protein, AdGFP served as the adenovirus control. In Groups 3, 4, and 5, flaps were pretreated with AdVEGF, AdAng1, and AdAng1 AdVEGF, respectively. Flaps were preserved in a subcutaneous pocket in the hindlimb for evaluation of functional capillary density and microvascular permeability indices at 3, 7, and 14 days by intravital microscopy system. At day 7 and 14, AdVEGF, AdAng1, and combined treatment groups showed significantly higher numbers of capillary densities when compared with control and AdGFP groups p< 0.05. At day 14, AdVEGF was the superior treatment group compared with AdAng1 and AdVEGF AdAng1 p< 0.05. Overall, there was a linear increase in the number of functional capillaries in all treatment groups p< 0.05. At day 3 after AdAngl therapy, a significantly lower permeability index was found when compared with AdVEGF AdAng1 and AdVEGF alone treatment p< 0.05. At day 7, the AdVEGF group had the highest score of permeability index compared with control, combined, and AdAng1 groups p< 0.05. Histologic evaluation of muscle flaps demonstrated mild focal inflammation. There was evidence of mild vasculitis in all flaps except control muscles. Intravascular angiogenic therapy with AdVEGF or AdAng1 was technically feasible, as demonstrated by expression of the control gene, GFP, along the vascular tree. All treatment groups increased perfusion of the muscle flap over a period of 14 days, indicating a longlasting effect of gene therapy. Ang1 alone or in combination with VEGF was as effective as VEGF alone in augmenting muscle perfusion with more stable vessels 1 week after gene therapy.