IL-18 binding protein-expressing mesenchymal stem cells improve myocardial protection after ischemia or infarction.

IL-18 is a proinflammatory cytokine known to cause tissue injury by inducing inflammation and cell death. Increased levels of IL-18 are associated with myocardial injury after ischemia or infarction. IL-18-binding protein (IL-18BP), the naturally occurring inhibitor of IL-18 activity, decreases the severity of inflammation in response to injury. In the present study, mesenchymal stem cells (MSCs) derived from mice transgenic for over expression of human lL-18BP were tested in rat models of global myocardial ischemia and acute myocardial infarction. Improved myocardial function is associated with production of VEGF, and in vitro, IL-18BP MSCs secreted higher levels of constitutive VEGF compared to wild-type MSC5. Whereas 11-18 increased cell death and reduced VEGF in wild-type MSC5, IL-18BP MSC5 were protected. In an isolated heart model, intracoronary infusion of IL-18BP MSCs before ischemia increased postischemic left ventricular (LV) developed pressure to 79.5 ± 9.47 mmHg compared to 59.3 ± 7.8 mmHg in wild-type MSCs and 37.8 ± S mmHg in the vehicle group. Similarly, using a coronary artery ligation model, intramyocardial injection of lL-18BP MSCs improved LV ejection fraction to 67.8 ± 1.76% versus wild-type MSC5 (57.4 ± 1.33%) and vehicle (39.2 ± 2.07%), increased LV fractional shortening 1.25-fold over wild-type MSCs and 1.95-fold over yehide, decreased infarct size to 38.8 ± 2.16% compared to 46.4 ± 1.92% in wild-type MSC5 and 60.7 ± 2.2% in vehicle, reduced adverse ventricular remodeling, increased myocardial VEGF production, and decreased 11-6 levels. This study provides the concept that IL-18BP genetically modified stem cells improve cardioprotection over that observed with unmodified stem cells. [ABSTRACT FROM AUTHOR]