Augmentation of revascularization and prevention of plasma leakage by angiopoietin-1 and vascular endothelial growth factor co-transfection in rats with experimental limb ischaemia

Background - Angiopoietin-1 (Ang1) and vascular endothelial growth factor (VEGF) are endothelial cell-specific growth factors. In the current study, we tested the hypothesis that co-expression of AngI and VEGF could have an effect on development of leakage-resistant vessels. Methods and results - Expression plasmids, pcD2 (control plasmid), pcD2/Ang1, pcD2/VEGF(121), or pcD2/AngI + pcD2/VEGF(121), were injected intramuscularly into an ischaemic hindlimb rat model, followed by electroporation. Collateral vessel development and skeletal muscle atrophy were assessed before and 7, 14, 28 days after treatment. Capillary density was significantly increased in the rats transfected with Ang1 or VEGF compared with that in the rats transfected with pcD2 alone (P < 0.05). Rats transfected with AngI + VEGF had the highest capillary density (P < 0.05). The mean perimeter ratio of ligated hindlimb to non-ligated hindlimb was lower with pcD2 treatment rats compared with that in the rats transfected with Ang1, VEGF or Ang1 +VEGF (P < 0.01). Limb necrosis was observed in two of 33 control rats, but none in the Ang1 and/or VEGF gene-transferred rats. The amount of extravasated Evans blue in rat ligated hindlimb muscle (7 days after treatment) treated with both Ang1 and VEGF was significantly less compared with that in the rats transfected with VEGF alone (P < 0.01). Conclusions - The current study demonstrated that co-expression of AngI and VEGF genes in the ischaemic muscle effectively develops leakage-resistant vessels in the rat model. Therefore, this approach may provide a more appropriate therapeutic strategy in ischaemic vascular diseases.