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Effects of VEGF121 and/or VEGF165 gene transfection on collateral circulation development
1Department of Medicine, Buddhist Tzu-Chi General Hospital, Hualien, Taiwan.
Background And Purpose:
Angiogenesis is regulated by various factors, including vascular endothelial growth factor (VEGF). Five isoforms of VEGF have been discovered: VEGF121, VEGF145, VEGF165, VEGF189, and VEGF206. The teleologic basis for the various VEGF isoforms remains unclear, but different VEGF isoforms may mediate distinct endothelial cell functions such as angiogenesis, vascular permeability, and differentiation. We sought to determine the effects of various VEGF isoforms on angiogenesis under ischemic conditions in rabbits.
Methods:
The effects of VEGF121 and/or VEGF165 gene transfection on collateral circulation development in ischemic rabbit hindlimb muscles were investigated by using naked plasmids encoding VEGF121 or VEGF165 (pVEGF121 or pVEGF165), either individually or in combination. pCMV beta was used as the control plasmid. The femoral artery on one side of New Zealand White rabbits was ligated. Ten days later, the ischemic muscles received direct intramuscular injection of pVEGF121 (500 micrograms), pVEGF165 (500 micrograms), or pVEGF121 (250 micrograms) + pVEGF165 (250 micrograms) in experimental groups, while pCMV beta (500 micrograms) was used in the control group. Therapeutic effects were evaluated 30 days later by anatomic and physiologic analysis.
Results:
Internal iliac angiography showed strong development of collateral circulation in all of the pVEGF-treated groups. In contrast, collateral arteries developed weakly in the control group. Combination treatment with both pVEGF121 and pVEGF165 did not result in additional improvement compared with pVEGF121 or pVEGF165 treatment alone (angiographic scores: pVEGF121 = 0.85 +/- 0.10; pVEGF165 = 0.81 +/- 0.11; pVEGF121 + pVEGF165 = 0.83 +/- 0.09; control = 0.53 +/- 0.09; p < 0.01). A favorable response in the development of circulation at the capillary level with pVEGF121 and/or pVEGF165 versus pCMV beta was also found. Blood pressure measurement and regional blood flow measurement using colored microspheres revealed similar results.
Conclusions:
Our results show that direct intramuscular injection of naked DNA encoding VEGF121 or VEGF165, individually or in combination, is an effective method for gene transfer in an animal model of ischemic limbs and results in augmented collateral vascular development and tissue perfusion.