Intravenous injection of phagocytes transfected ex vivo with FGF4 DNA/biodegradable gelatin complex promotes angiogenesis in a rat myocardial ischemia/reperfusion injury model.

Conventional gene therapies still present difficulties due to poor tissue-targeting, invasiveness of delivery, method, or the use of viral vectors. To establish the feasibility of using non-virally ex vivo transfected phagocytes to promote angiogenesis in ischemic myocardium, gene-transfection into isolated phagocytes was performed by culture with positively charged gelatin impregnated with plasmid DNA. A high rate of gene transfection was achieved in rat macrophages and human monocytes, but not in mouse fibroblasts. The efficiency was 68 ± 11% in rat macrophages and 78 ± 8% in human monocytes. Intravenously injected phagocytes accumulated predominantly in ischemic tissue (13 ± 8%) and spleen (84 ± 6%), but negligibly in other organs in rodents. The efficiency of accumulation in the target ischemic tissue reached more than 86% on direct local tissue injection. In a rat model of myocardial ischemia-reperfusion, intravenous injection of fibroblast growth factor 4 (FGF4)-gene-transfected macrophages significantly increased regional blood flow in the ischemic myocardium (78 ± 7.1 % in terms of flow ratio of ischemic/non-ischemic myocardium) compared with intravenous administration of saline (36 ± 11%) or nontransfected macrophages (42 ± 12 %), or intramuscular administration of naked DNA encoding FGF4 (75 ± 18 %). Enhanced angiogenesis in the ischemic tissue we confirmed histologically. Similarly, intravenous injection of FGF4-gene-transfected monocytes enhanced regional blood flow in an ischemic hindlimb model in mice (93 ± 22 %), being superior to the three other treatments described above (38 ± 12, 39 ± 15, and 55 ± 12%, respectively).