Sphingosine Kinase Protects Heart Against Ischemia-Reperfusion Induced Injury And Attenuates Its Post-Ischemic Failure

Sphingosinel-phosphate (S1P), the sphingolipid metabolite mainly catalyzed by sphingosine kinase 1 (SPK1), has been shown to protect heart from hypoxia-induced injury. And SPK1 has been identified as a central mediator of cardiac ischemia preconditioning. However, the application of SPK1 gene transfer to treat myocardial ischemia and postinfarction heart failure has not yet been tried. We observed the protective effect of adenovirus-mediated SPK1 gene transfer on H₂O₂-induced cardiomyocyte death and ischemia-reperfusion induced cardiac injury in an isolated perfused rat heart model. Furthermore, its therapeutic action was evaluated by using a rat model of postinfarction heart failure. H₂O₂ administration resulted in cardiomyocyte death in a dose-dependent manner. SPK1 activity and Edg-3 expression were inhibited, but Edg-1 expression was increased by H₂O₂ administration. Both Ad-SPK1 infection and exogenous S1P could significantly prevent cardiomyocytes from H₂O₂-induced death. In rats, on day 3 after intramyocardial injection of adenovirus carrying human SPK1 gene (Ad-SPK1), and the adenovirus carrying a gene encoding green fluorescence gene protein (Ad-GFP) as a control respectively, the hearts were isolated and subjected to non-flow ischemia/reperfusion (I/R) (30 minutes/30 minutes) using the Langendorff preparation. The cardiac SPK1 activity was increased about five times by injection of Ad-SPK1, in compare to Ad-GFP control group. And Ad-SPK1-transfected hearts well performed over the whole reperfusion period. The creatine kinase (CK) release and the incidence of arrhythemia during the reperfusion in these hearts were also slight. These results indicated that adenovirus-mediated SPK1 gene transfer protects heart from injury induced by ischemia-reperfusion. To investigate the effect of SPK1 gene transfer in the treatment of postischemia heart failure, the left anterior descending branch of coronary artery in Wistar rats was ligated following direct intramyocardial injection of Ad-SPK1 or Ad-GFP as control, and the blood supply and function of heart was analyzed after two weeks. We demonstrated that SPK1 gene transfer well preserved cardiac systolic and diastolic function, as measured by left ventricular systolic pressure (LVSP)(Ad-SPKl 132.82±13.03 versus Ad-GFP 76.96±8.44 mmHg,p<0.01;), left ventricular end-diastolic pressure (LVEDP)( Ad-SPK1 4.34±0.69 versus Ad-GFP 14.79±1.08 mmHg,p<0.01) and maximum dP/dt (Ad-SPK1 5095.20±384.79 versus Ad-GFP 2954.12±195.05,p<0.01). It was also found that the LV morphometric parameters were well preserved, being associated with Ad-SPK1 treatment (Ad-SPK1 versus Ad-GFP in infarct size: 3.78±0.96 versus 38.86±5.68 (%),p<0.01; LV diameter: 4.63±0.80 versus 7.30±1.03 mm,p<0.01; LV wall thickness 2.70±0.29 versus 1.34±0.36 mm, p<0.01). SPK1 gene transfer also significantly enhanced angiogenesis that was measured by both Von Willebrand's Factor immunohistochemical staining and blood vessel counting, and reduced fibrosis determined by Sirius Red staining. In conclusion, Adenovirus-mediated SPK1 gene transfer could efficiently protect I/R-induced myocardial injury and attenuate postischemic heart failure via enhancing angiogenesis and reducing fibrosis. These findings imply that adenovirus-mediated SPK1 gene transfer might provide a novel strategy for treatment of the coronary heart disease.