Objective: Endothelial dysfunction and decreased nitric oxide bioavailability may explain why therapeutic angiogenesis and cell therapy have mostly failed in humans. Building from previous large animal work, the Phase I Endothelial Modulation in Angiogenic Therapy trial tested the hypothesis that L-arginine, a nitric oxide donor, may be safe and effective in potentiating surgical angiogenesis in humans.
Methods: Patients with surgical triple-vessel coronary disease and a severely diffusely diseased left anterior descending artery were randomized in 2 x 2 factorial fashion to receive ten 200-microg injections of vascular endothelial growth factor-165 plasmid DNA or placebo in the anterior myocardium along the proximal and mid-left anterior descending arteries, plus oral L-arginine supplementation at a dose of 6 g per day or placebo for 3 months. The distal left anterior descending artery and other coronary arteries were grafted. End points included 3-month changes in myocardial perfusion and contractility of the anterior myocardium, using (13)N-ammonia positron emission tomography and echocardiography. Baseline scans were obtained 3 to 7 days postoperatively to delineate treatment effects from the effects of coronary artery bypass grafting.
Results: Patient (N = 19) characteristics were equivalent between groups. There was no perioperative or late mortality. Patients who received the combination of vascular endothelial growth factor and L-arginine had improved anterior wall perfusion on positron emission tomography (P = .02), a trend toward smaller perfusion defects (P = .10), and better anterior wall contractility (P = .02, Kruskal-Wallis) at 3 months versus baseline. This was corroborated by a trend toward better disease perception at 3 months versus baseline on the Seattle Angina Questionnaire (score improvement of 47 +/- 35, combination treatment group; P = .1, Kruskal-Wallis).
Conclusion: To our knowledge, this is the first study to examine concomitant substrate modification in patients undergoing new biosurgical therapies by using vascular endothelial growth factor angiogenesis. The results suggest safety and efficacy. Concomitant endothelial modulation with L-arginine not only has the potential to make angiogenesis effective but also may have implications for cell therapy trials.