Targeted delivery of VEGF to treat myocardial infarction.

Noninvasive injection of pro-angiogenic compounds such as vascular endothelial growth factor (VEGF) has shown promising results in regenerating cardiac microvasculature. However, these results have failed to translate into successful clinical trials in part due to the short half-life of VEGF in circulation. Increasing the dose of VEGF may increase its availability to the target tissue, but harmful side-effects remain a concern. Encapsulating and selectively targeting VEGF to the MI border zone may circumvent these problems. Anti-P-selectin conjugated immunoliposomes containing VEGF were developed to target the infarct border zone in a rat MI model. Targeted VEGF therapy significantly improves vascularization and cardiac function after an infarction.

Targeting VEGF-encapsulated immunoliposomes to MI heart improves vascularity and cardiac function.

Recent attempts at rebuilding the myocardium using stem cells have yielded disappointing results. The lack of a supporting vasculature may, in part, explain these disappointing findings. However, concerns over possible side effects have hampered attempts at revascularizing the infarcted myocardium using systemic delivery of proangiogenic compounds. In this study, we develop the technology to enhance the morphology and function of postinfarct neovasculature. Previously, we have shown that the up-regulated expression of endothelial cell adhesion molecules in the myocardial infarction (MI) region provides a potential avenue for selectively targeting drugs to infarcted tissue. After treatment with anti-P-selectin-conjugated liposomes containing vascular endothelial growth factor (VEGF), changes in cardiac function and vasculature post-MI were quantified in a rat MI model. Targeted delivery of VEGF to post-MI tissue resulted in significant increase in fractional shortening and improved systolic function. These functional improvements were accompanied by a 21% increase in the number of anatomical vessels and a 74% increase in the number of perfused vessels in the MI region of treated animals. No significant improvements in cardiac function were observed in untreated, systemic VEGF-treated, nontargeted liposome-treated, or blank immunoliposome-treated animals. Targeted delivery of low doses of proangiogenic compounds to post-MI tissue results in significant improvements in cardiac function and vascular structure.