Combined Gene Therapy with Hypoxia-Inducible Factor-1 alpha and Heme Oxygenase-1 for Therapeutic Angiogenesis

Abstract

Transfection with either hypoxia-inducible factor-1 alpha (HIF-1 alpha) or heme oxygenase-1 (HO-1) gene can induce neovascularization in ischemic tissues. Although expression of transfected HIF-1 alpha gene occurs rapidly, the expressed HIF-1 alpha protein degrades quickly, limiting its therapeutic efficacy. Meanwhile, expressed HO-1 protein does not rapidly undergo degradation, but gene expression occurs a couple of days after transfection, resulting in apoptosis and a delay in angiogenesis in ischemic tissues at the incipient period of HO-1 gene transfection. We hypothesize that combined delivery of HIF-1 alpha and HO-1 gene will enhance antiapoptosis and neovascularization in ischemic tissue compared with HIF-1 alpha or HO-1 single-gene therapy. To test this hypothesis, ischemic mouse hindlimbs were treated with HIF-1 alpha and/or HO-1 gene therapy. The combined gene therapy proved superior to both single-gene therapies, resulting in rapid expression of HIF-1 alpha gene and long-term maintenance of expressed HO-1 protein. The apoptosis in the ischemic region was significantly less, and angiogenic growth factor secretion and angiogenesis were greater in the combined gene therapy than in either of the single-gene therapies. Our results suggest that a combined gene therapy of HIF-1 alpha and HO-1 enhances the transfection of both genes and improves angiogenesis compared with either single-gene therapy.