CXC-Chemokine Receptor 4 Antagonist AMD3100 Promotes Cardiac Functional Recovery After Ischemia/Reperfusion Injury via Endothelial Nitric Oxide Synthase–Dependent Mechanism

Abstract

Background—: CXC-chemokine receptor 4 (CXCR4) regulates the retention of stem/progenitor cells in the bone marrow (BM), and the CXCR4 antagonist AMD3100 improves recovery from coronary ligation injury by mobilizing stem/progenitor cells from the BM to the peripheral blood. Thus, we investigated whether AMD3100 also improves recovery from ischemia/reperfusion injury, which more closely mimics myocardial infarction in patients, because blood flow is only temporarily obstructed. Methods and Results—: Mice were treated with single subcutaneous injections of AMD3100 (5 mg/kg) or saline after ischemia/reperfusion injury. Three days later, histological measurements of the ratio of infarct area to area at risk were smaller in AMD3100-treated mice than in mice administered saline, and echocardiographic measurements of left ventricular function were greater in the AMD3100-treated mice at week 4. CXCR4 ⁺ cells were mobilized for just 1 day in both groups, but the mobilization of sca1 ⁺ /flk1 ⁺ cells endured for 7 days in AMD3100-treated mice compared with just 1 day in the saline-treated mice. AMD3100 upregulated BM levels of endothelial nitric oxide synthase (eNOS) and 2 targets of eNOS signaling, matrix metalloproteinase-9 and soluble Kit ligand. Furthermore, the loss of BM eNOS expression abolished the benefit of AMD3100 on sca1 ⁺ /flk1 ⁺ cell mobilization without altering the mobilization of CXCR4 ⁺ cells, and the cardioprotective effects of AMD3100 were retained in eNOS-knockout mice that had been transplanted with BM from wild-type mice but not in wild-type mice with eNOS-knockout BM. Conclusions—: AMD3100 prolongs BM progenitor mobilization and improves recovery from ischemia/reperfusion injury, and these benefits appear to occur through a previously unidentified link between AMD3100 and BM eNOS expression.