Effect of vascular endothelial growth factor gene transfer on infarct size, left ventricular function and myocardial perfusion in sheep after 2months of coronary artery occlusion

Background: In large mammalian models of acute myocardial infarction (AMI), plasmid-mediated vascular endothelial growth factor (pVEGF) gene transfer has been shown to induce angio-arteriogenesis, proliferation of myocyte precursors and adult cardiomyocyte mitosis, reducing infarct size at 15days after coronary artery occlusion. However, it is unknown whether these effects persist at longer follow-up times, nor how they affect cardiac performance. We thus assessed infarct size, left ventricular (LV) function and perfusion in 2-month-old ovine AMI. Methods: Adult sheep with coronary artery occlusion were randomized to blindly receive ten intramyocardial injections of 3.8mg of pVEGF or empty plasmid distributed at the infarct border. Three and 60days later, LV perfusion (single-photon emission computed tomography) and function (stress echocardiography) were assessed. Finally, hemodynamics (LV catheterization), scar size and peri-infarct histology were studied. Results: Infarct size was 30% smaller in pVEGF-treated sheep (23.6±1.9% versus 32.7±2.7% of the LV; p<0.02). Percentage fractional shortening and wall thickening at the infarct border improved after pVEGF, as did myocardial perfusion and LV wall motion under pharmacological stress. Global LV function did not differ between groups, although the force-frequency response was preserved in pVEGF group and lost in placebo animals. These effects were associated with angio-arteriogenesis and proliferation of cardiomyocyte precursors. Conclusions: In sheep with AMI, pVEGF gene transfer affords long-term infarct size reduction, yielding regional LV function and perfusion improvement and reducing remodeling progression. These results suggest the potential usefulness of this approach in the clinical setting.Fil: Vera Janavel, Gustavo L.. Universidad Favaloro. Área de Investigación y Desarrollo; ArgentinaFil: De Lorenzi, Andrea. Fundación Favaloro; ArgentinaFil: Cortés, Claudia. Fundación Favaloro; ArgentinaFil: Olea, Fernanda Daniela. Universidad Favaloro. Área de Investigación y Desarrollo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cabeza Meckert, Patricia. Fundación Favaloro; ArgentinaFil: Bercovich, Andrés. Biosidus S. A.; ArgentinaFil: Criscuolo, Marcelo. Biosidus S. A.; ArgentinaFil: Laguens, Rubén. Universidad Favaloro. Área de Investigación y Desarrollo; ArgentinaFil: Crottogini, Alberto Jose. Universidad Favaloro. Área de Investigación y Desarrollo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Reference values for echocardiographic parameters and indexes of left ventricular function in healthy, young adult sheep used in translational research: comparison with standardized values in humans

Ovine models of ischemic heart disease and cardiac failure are increasingly used in translational research. However, reliable extrapolation of the results to the clinical setting requires knowing if ovine normal left ventricular (LV) function is comparable to that of humans. We thus assessed for echocardiographic LV dimensions and indexes in a large normal adult sheep population and compared them with standardized values in normal human adults. Bidimensional and tissue Doppler echocardiograms were performed in 69 young adult Corriedale sheep under light sedation. LV dimensions and indexes of systolic and diastolic function were measured. Absolute and body surface areanormalized values were compared to those for normal adult humans and their statistical distribution was assessed. Normalized dimensions (except for end diastolic diameter) as well as ejection fraction and fractional shortening fell within the ranges established by the American Society of Echocardiography and European Association of Echocardiography for normal adult humans. Normalized end diastolic diameter exceeded the upper normal limit but got close to it when correcting for the higher heart mass/body surface area ratio of sheep with respect to humans. Diastolic parameters also fell within normal human ranges except for a slightly lower mitral deceleration time. All values exhibited a Gaussian distribution. We conclude that echocardiographic parameters of systolic and diastolic LV performance in young adult sheep can be reliably extrapolated to the adult human, thus supporting the use of ovine models of human heart disease in translational research

Repeated, but not single, VEGF gene transfer affords protection against ischemic muscle lesions in rabbits with hindlimb ischemia

Vascular endothelial growth factor (VEGF) gene transfer-mediated angiogenesis has been proposed for peripheral artery disease. However, protocols using single administration have shown little benefit. Given that the transient nature of VEGF gene expression provokes instability of neovasculature, we hypothesized that repeated administration would provide efficient tissue protection. We thus compared single vs repeated transfection in a rabbit model of hindlimb ischemia by injecting a plasmid encoding human VEGF165 (pVEGF165) at 7 (GI, n=10) or 7 and 21 (GII, n=10) days after surgery. Placebo animals (GIII, n=10) received empty plasmid. Fifty days after surgery, single and repeated administration similarly increased saphenous peak flow velocity and quantity of angiographically visible collaterals. However, microvasculature increased only with repeated transfection: capillary density was 49.4±15.4 capillaries per 100 myocytes in GI, 84.6±14.7 in GII (P<0.01 vs GI and GIII) and 49.3±13.6 in GIII, and arteriolar density was 1.9±0.6 arterioles per mm2 in GI, 3.0±0.9 in GII (P<0.01 vs GI and GIII) and 1.5±0.6 in GIII. Muscle lesions were reduced only within repeated transfection. With single administration, gene expression peaked at 7 days and declined rapidly, but with repeated administration, it remained positive at 50 days. At 90 days of repeated transfection (additional animals), gene expression decreased significantly, but neovessel densities did not. Thus, repeated, but not single, VEGF gene transfection resulted in increased microvasculature, which, in turn, afforded effective protection against ischemic muscle damage.Fil: Olea, Fernanda Daniela. Universidad Favaloro. Área de Investigación y Desarrollo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Vera Janavel, G.. Universidad Favaloro. Área de Investigación y Desarrollo; ArgentinaFil: Cuniberti, Luis Alberto. Universidad Favaloro. Área de Investigación y Desarrollo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Yannarelli, Gustavo Gabriel. Universidad Favaloro. Área de Investigación y Desarrollo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cabeza Meckert, Patricia. Universidad Favaloro. Área de Investigación y Desarrollo; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; ArgentinaFil: Cors, J.. Universidad Favaloro. Área de Investigación y Desarrollo; ArgentinaFil: Valdivieso, L.. Universidad Favaloro. Área de Investigación y Desarrollo; ArgentinaFil: Lev, G.. Universidad Favaloro. Área de Investigación y Desarrollo; ArgentinaFil: Mendiz, O.. Universidad Favaloro. Área de Investigación y Desarrollo; ArgentinaFil: Bercovich, A.. Universidad Favaloro. Área de Investigación y Desarrollo; ArgentinaFil: Criscuolo, M.. Biosidus S. A.; ArgentinaFil: Melo, C.. Biosidus S. A.; ArgentinaFil: Laguens, R.. Universidad Favaloro. Área de Investigación y Desarrollo; ArgentinaFil: Crottogini, Alberto José. Universidad Favaloro. Área de Investigación y Desarrollo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin