Engineered zinc finger-activating vascular endothelial growth factor transcription factor plasmid DNA induces therapeutic angiogenesis in rabbits with hindlimb ischemia

Background - Therapeutic angiogenesis seeks to promote blood vessel growth to improve tissue perfusion. Vascular endothelial growth factor (VEGF) exists in multiple isoforms. We investigated an engineered zinc finger-containing transcription factor plasmid designed to activate the endogenous VEGF gene (ZFP-VEGF). Methods and Results - New Zealand White rabbits (n=56) underwent unilateral femoral artery ligation and excision. At day 10 postoperatively, the ischemic muscle received ZFP treatment (500 μg ZFP-VEGF plasmid) or no ZFP treatment (β-galactosidase, empty, or no plasmid). Group 1 (n=13) was harvested 3 days after injection to examine VEGF mRNA by real-time polymerase chain reaction and protein by ELISA. Groups 2 (n=13) and 3 (n=10) were harvested 11 days after injection. Group 2 was studied by histology and group 3, by histology and changes in blood flow. Groups 4 and 5 (n=10 each) were harvested 22 and 32 days after injection, respectively, and studied for changes in blood flow. In group 1, VEGF mRNA copy numbers were significantly higher for VEGF ₁₂₁, VEGF₁₆₅, VEGF₁₈₉, and protein in the ZFP-VEGF-treatment versus no-ZFP-treatment arms. In groups 2 and 3, capillary density and proliferating cells were significantly greater and apoptosis significantly lower in the treatment versus no-treatment arms. Changes in the blood flow ratio of the ischemic to the nonischemic limb were significantly greater in the treatment versus no-ZFP-treatment groups (6.57±1.52% versus 3.38±0.87%, P<0.005; 13.15±1.77% versus 6.13±1.55%, P<0.001; and 20.16±2.84% versus 13.88±3.14%, P<0.01, for groups 3, 4, and 5, respectively). Conclusions - This engineered ZFP-VEGF-activating transcription factor may provide a novel approach to treat peripheral arterial disease.