HIF-1 alpha gene therapy(The Johns Hopkins University)

Diabetes mellitus is a common comorbidity of atherosclerosis. Hypoxia‐inducible factor‐1 (HIF‐1) is the master regulator of the angiogenic response to hypoxia.

We studied the effects of adenoviral vectors expressing a constitutively active HIF‐1α hybrid (Ad2/HIF‐1α/VP16) or vascular endothelial growth factor (Ad2/VEGF) on collateral development and vascular leakiness in a diabetic rat model of hindlimb ischemia.

After the removal of the right femoral artery, the mRNA levels of VEGF, angiopoietin‐1 and angiopietin‐4 in the calf muscles, as measured by Taqman reverse transcriptase‐polymerase chain reaction, were transiently elevated in Zucker lean (ZL) but not Zucker diabetic fatty (ZDF) rats. The angiographic score, as determined by post‐mortem angiography, was significantly lower in ZDF animals 35 days after surgery compared to their ZL counterparts. In separate animals, intramuscular injection of Ad2/HIF‐1a/VP16 and Ad/2VEGF into the thigh muscles significantly increased the angiographic score and capillary density 21 and 35 days after the injection compared to Ad2/CMVEV (a vector expressing no transgene) or vehicle. After the injection of Ad2/CMVEV or vehicle, the Evans‐blue dye content in the thigh muscles was significantly higher in ZDF rats than their ZL counterparts. Ad2/HIF‐1α/VP16 but not Ad2/VEGF reduced tissue Evans blue dye content.

The endogenous angiogenic response to ischemia was impaired in ZDF rats, possibly due to down‐regulation of angiogenic factors. Ad2/HIF‐1α/VP16 enhanced collateral development and reduced vascular leakage in the ischemic hindlimb of ZDF rats indicating that hybrid HIF‐1α angiogenic therapy may be efficacious for peripheral vascular disease with a diabetic comorbidity. Copyright © 2009 John Wiley & Sons, Ltd.

Background— Critical limb ischemia, a manifestation of severe peripheral atherosclerosis and compromised lower-extremity blood flow, results in a high rate of limb loss. We hypothesized that adenoviral delivery of a constitutively active form of the transcription factor hypoxia-inducible factor-1α (ie, Ad2/HIF-1α/VP16 or HIF-1α) into the lower extremity of patients with critical limb ischemia would be safe and might result in a durable clinical response. Methods and Results— This phase I dose-escalation program included 2 studies: a randomized, double-blind, placebo-controlled study and an open-label extension study. In total, 34 no-option patients with critical limb ischemia received HIF-1α at doses of 1×10 8 to 2×10 11 viral particles. No serious adverse events were attributable to study treatment. Five deaths occurred: 3 in HIF-1α and 2 in placebo patients. In the first (randomized) study, 7 of 21 HIF-1α patients met treatment failure criteria and had major amputations. Three of the 7 placebo patients rolled over to receive HIF-1α in the extension study. No amputations occurred in the 2 highest-dose groups of Ad2/HIF-1α/VP16 (1×10 11 and 2×10 11 viral particles). The most common adverse events included peripheral edema, disease progression, and peripheral ischemia. At 1 year, limb status observations in HIF-1α patients included complete rest pain resolution in 14 of 32 patients and complete ulcer healing in 5 of 18 patients. Conclusions— HIF-1α therapy in patients with critical limb ischemia was well tolerated, supporting further, larger, randomized efficacy trials.