Selective homocysteine lowering gene transfer improves infarct healing, attenuates remodelling, and enhances diastolic function after myocardial infarction in mice.

BACKGROUND AND AIMS

Homocysteine levels predict heart failure incidence in prospective epidemiological studies and correlate with severity of heart failure in cross-sectional surveys. The objective of this study was to evaluate whether a selective homocysteine lowering intervention beneficially affects cardiac remodelling and cardiac function after myocardial infarction (MI) in a murine model of combined hypercholesterolemia and hyperhomocysteinemia.

METHODOLOGY AND PRINCIPAL FINDINGS

A selective homocysteine lowering gene transfer strategy was evaluated in female C57BL/6 low density lipoprotein receptor (Ldlr)⁻/⁻ cystathionine-ß-synthase (Cbs)⁺/⁻ deficient mice fed a hyperhomocysteinemic and high saturated fat/high cholesterol diet using an E1E3E4-deleted hepatocyte-specific adenoviral vector expressing Cbs (AdCBS). MI was induced by permanent ligation of the left anterior descending coronary artery 14 days after saline injection or gene transfer. AdCBS gene transfer resulted in a persistent more than 5-fold (p<0.01) decrease of plasma homocysteine levels and significantly improved endothelial progenitor cell function. Selective homocysteine lowering enhanced infarct healing as indicated by a 21% (p<0.01) reduction of infarct length at day 28 after MI and by an increased number of capillaries and increased collagen content in the infarct zone. Adverse remodelling was attenuated in AdCBS MI mice as evidenced by a 29% (p<0.05) reduction of left ventricular cavity area at day 28, by an increased capillary density in the remote myocardium, and by reduced interstitial collagen. The peak rate of isovolumetric relaxation was increased by 19% (p<0.05) and the time constant of left ventricular relaxation was reduced by 21% (p<0.05) in AdCBS MI mice compared to control MI mice, indicating improved diastolic function.

CONCLUSION/SIGNIFICANCE: Selective homocysteine lowering gene transfer improves infarct healing, attenuates remodelling, and significantly enhances diastolic function post-MI in female C57BL/6 Ldlr⁻/⁻ Cbs⁺/⁻ mice. The current study corroborates the view that hyperhomocysteinemia exerts direct effects on the myocardium and may potentiate the development of heart failure.