Polymeric gene delivery of ischemia-inducible VEGF significantly attenuates infarct size and apoptosis following myocardial infarct

The development of clinically beneficial myocardial gene therapy has been slowed by reliance on the use of viral carriers and non-physiologic, constitutive gene expression. To specifically address these issues, we have developed a non-viral gene carrier, water-soluble lipopolymer (WSLP), and an ischemia-inducible plasmid construct expressing vascular endothelial growth factor (VEGF), pRTP801-VEGF, to treat myocardial ischemia and infarction. Rabbits underwent ligation of the circumflex artery followed by injection of (a) an ischemia-inducible VEGF gene construct in a WSLP carrier; (b) a constitutively expressed, or unregulated, SV-VEGF gene construct in a WSLP carrier; (c) WSLP carrier alone; or (d) no injection therapy. Following 4 weeks treatment, ligation alone resulted in infarction of 48 +/- 7% of the left ventricle. With injection of WSLP carrier alone, 49 +/- 6% of the left ventricle was infarcted (P = NS). The constitutively expressed gene construct, SV-VEGF, reduced the infarct size to 32 +/- 7% of the left ventricle (P = 0.007). The ischemia-inducible gene construct, RTP801-VEGF, further reduced the infarct size to 13 +/- 4% of the left ventricle (P < 0.001). The use of a non-viral carrier to deliver an ischemia-inducible VEGF construct is effective in the treatment of acutely ischemic myocardium.