Non-angiogenic FGF-2 protects the ischemic heart from injury, in the presence or absence of reperfusion

OBJECTIVE: Fibroblast growth factor-2 (FGF-2), given during ischemia or during reperfusion of the ischemic heart is cardioprotective, but its mitogenic activity may limit possible clinical applications. We have tested the cardioprotective potential of a non-mitogenic FGF-2 mutant (S117A) that no longer activates casein kinase 2 (CK2) in both acute and long-term studies. METHODS AND RESULTS: To test effects during reperfusion, the ex vivo rat heart, subjected to 30 min of global ischemia and 60 min of reperfusion was used. S117A FGF-2 administered during reperfusion protected against myocardial contractile dysfunction, activated protein kinase C and decreased the release of cytochrome C in the cytosol. To study effects on ischemic myocytes in the absence of reperfusion, myocardial infarction (MI) was induced in the rat model by irreversible left coronary ligation. S117A-, wild type (wt)-FGF-2 or saline, were administered by intramyocardial injection into the ischemic ventricular wall. One day later, infarct size (assessed by tetrazolium staining), and plasma cardiac troponin T levels (assessed by Western blotting) were significantly decreased in the S117A FGF-2-, compared to the saline-treated group. Systolic pressure, rates of contraction and relaxation and developed pressure, assessed in the Langendorff mode, were significantly improved in the S117-FGF-2 group. Improved ejection fraction and fractional shortening in the S117A-treated group were maintained up to, but not beyond, 7 days post-MI. In comparison, improvements were maintained in the wt-FGF-2-treated group at least up to 6 weeks post-MI. At 6 weeks post-MI, small vessel density (assessed by immunofluorescence-based detection) in the scar bordering viable myocardium was similar between S117A-FGF-2- and saline-treated hearts, but significantly increased in the wt-FGF-2-treated group. This was accompanied by increased coronary flow in the wt-, but not S117A-FGF-2-treated hearts, compared to controls. CONCLUSION: The ability of FGF-2, administered during ischemia or during reperfusion, to protect the myocardium acutely from tissue loss and dysfunction is independent of its potential for CK2 activation and angiogenesis. Non-angiogenic S117A-FGF-2 may be considered in therapies aiming for acute prevention of reperfusion-associated pathologies, especially in cases where use of mitogens is counter-indicated.