The broad objective of this program is to perform preclinical experimentation on animal models of myocardial ischemia and heart failure to elucidate the mechanisms of their development and to evaluate the potential of different therapeutic modalities including gene therapy with angiogenic growth factors. Using the hindlimb ischemia model, we have recently shown that adenovirus-mediated intramuscular (IM) gene therapy with vascular endothelial growth factor (AdCMV.VEGF121) augments collateral vessel development in nonischemic skeletal muscles and, subsequently, attenuates the hemodynamic deficit related to induced ischemia. We have also shown that treatment with VEGF165 encoded in plasmid/liposome complex stimulates angiogenesis in rabbits hindlimb ischemia model. In keeping with a broad objective of the program we mustered the techniques for in vivo assessment of cardiac function in rats and mice - the high resolution Doppler-Echocardiography and pressure/volume loop analysis with intracardiac pressure-conductance catheter. Using this """"""""cutting edge"""""""" technology we are conducting extensive functional and dynamic characterization of chronic heart failure which is developing subsequently to ligation of a coronary artery in mice and rats. This experimental model will be used for gene therapy experiments and for transgenic-based studies of the role of different receptors pathways in development of heart failure. Using the experimental model of myocardial infarction in mice we identified and characterized previously overlooked phenotype of chronic heart failure associated with small, non-transmural infarction. This phenotype was not accompanied by left ventricular enlargement and was characterized by increased ventricular elastance in end-systole and stiffness in end- diastole, i.e., it might represent a diastolic model of heart failure. Increased ventricular elastance in this phenotype matched the increased arterial elastance so that ventricular-arterial coupling remains preserved. In longitudinal study we showed that development of this non-dilated phenotype was independent from usually described dilated phenotype characterized by reduced ventricular elastance. Patients with distal and diffuse, coronary artery disease present a major clinical problem. Hyperlipidemia, diabetes, and advanced age are major predisposing factors in its development. Ischemic disease of this type is not amenable to revascularization by coronary artery bypass grafting or catheter-based procedures and results in accelerated development of heart failure. Novel therapeutic approaches are needed for this disease and myocardial revascularization through gene therapy-induced angiogenesis seems as a good alternative. Our current research is directed on development and characterization of the experimental model of distal and diffuse CAD using coronary microembolization in rats to simulate the damage of numerous small arterioles. In experiment on rats we have shown that microembolization of coronary arteries with 15 micrometers synthetic non-degradable microspheres resulted in gradual ventricular remodeling accompanied by reduction of systolic function. Weekly Doppler echocardiography tests after microembolization showed the gradual increase in left ventricular end-systolic and end- diastolic volumes and reduction in ejection fraction. We are also working on development of effective and minimally invasive, gene delivery technique which would provide for extensive myocardial transfection. Poliakova L., Kovesdi I., Wang X., Capogrossi M.C., Talan M. Vascular permeability effect of adenovirus-mediated vascular endothelial growth factor gene transfer to the rabbit and rat skeletal muscle. J. of Thoracic and Cardiovascular Surgery, 118(2):339-47, 1999 Gowdak L.H.W., Poliakova L., Li Z., Grove R., Lakatta E.G., and Talan M.I. Induction of angiogenesis by cationic lipid-mediated VEGF165 gene transfer in the rabbit ischemic hindlimb model. Journal of Vascular Surgery, 32(2): 343-352, 2000. Gowdak L.H.W., Poliakova L., Wang X., Kovesdi I.,Fishbein K.W., Zacheo A., Palumbo R., Straino S., Emanueli C., Marrocco-Trishitta M., Lakatta E.G., Anversa P., Spencer R.G.S., Talan M., Capogrossi M.C. Adenovirus-mediated VEGF121 gene transfer stimulates angiogenesis in normoperfused skeletal muscle and preserves tissue perfusion after induction of ischemia. Circulation, 102(5): 565-571, 2000.
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