No abstract

Vessel stabilisation and the inhibition of side-effects such as tissue edema are essential in angiogenic gene therapy. Thus, combination gene transfers (GT) stimulating both endothelial cell and pericyte proliferation have become of interest. However, there is currently little data to support combination GT in large animal models. In this study we evaluated the potential advantages of such a strategy by combining the transfer of adenoviral (Ad) vascular endothelial growth factor A (VEGF-A) and platelet derived growth factor B (PDGF-B) into rabbit hindlimb skeletal muscle. AdLacZ alone or in combination with AdVEGF-A were used as controls. Contrast-enhanced ultrasound, modified Miles assay and immunohistology were used to quantify perfusion, vascular permeability and capillary size, respectively. Confocal microscopy was utilized in the assessment of pericyte-coverage. The transfer of AdPDGF-B alone and in combination with AdVEGF-A induced prominent proliferation of α-sma-, CD31-, RAM11-, HAM56-, and VEGF- positive cells. Although, pericyte recruitment to angiogenic vessels was not improved, combination GT induced a longer-lasting increase in perfusion in both intact and ischemic muscles than AdVEGF-A GT alone. In conclusion, intramuscular delivery of AdVEGF-A and AdPDGF-B, combined, resulted in a prolonged angiogenic response. However, the effects were most likely mediated via paracrine mechanisms rather than an increase in vascular pericyte coverage.

AdVEGF-B(186) and AdVEGF-E are equally potent in inducing therapeutic angiogenesis in mouse myocardium and produce less side effects than AdVEGF-A(165).