Current treatment of coronary insufficiency with angioplasty or coronary bypass could be complicated by restenosis in about one third of the cases. The discovery of angiogenic factors that promote blood vessel growth such as VEGF and FGF has stimulated the investigation of using them for the treatment of coronary disease. Direct injection of the growth factors only produces transient effect. The gene encoding for angiogenic factors delivered in the form of plasmic DNA, or by adenoviral vectors are currently being tested. We propose to deliver the genes encoding for angiogenic factors by AAV vectors. AAV appears to be an ideal vector for the delivery of angiogenic factors as it is nonpathogenic. Intramuscular injection of AAV vectors has been shown to be an efficient way of delivering secretory proteins such as erythropoietin and Factor IX. Our preliminary studies indicate that VEGF delivered by AAV vectors into the myocardium can stimulate new blood vessel growth in the myocardium of mice with occluded coronary arteries.
The aims of this proposal are: (1) We will verify and extend these preliminary findings by using a rat model in addition to the mouse; rat because the pathophysiologic consequences of coronary occlusion are better understood and the techniques for measuring them well established; and mice because the 3 dimensional structure of the coronary vasculature can be visualized by a new CT technique. Effect of AAV delivered angiogenic factors on left ventricular functions will be determined by echocardiography and measurement with the pressure-volume catheter. (2) We will regulate the expression of the genes for angiogenic factors to avoid over expression, which may cause angioma formation. The hypoxia responsive element of the Epo and VEGF gene will first be investigated. Alternatively, other inducible system will also be tested. (3) We will compare the effectiveness of AAV delivery of the genes for VEGF and angiopoietins, alone and in different combinations. These studies may lead to an effective approach for the treatment of coronary insufficiency.
