Intravenously Injected Mesenchymal Stem Cells Home to Infarcted Myocardium Without Altering Cardiac Function

Background： Systemic delivery of mesenchymal stem cells （MSCs） to the infarcted myocardium is an attractive noninvasive strategy, but therapeutic effect of this strategy remain highly controversial. Methods： Myocardial infarction was induced in female Sprague-Dawley rats by transient ligation of the left anterior descending coronary artery for 60 min. Either 2.5 × 106 DiI-labeled MSCs or equivalent saline was injected into the tail vein at 24 h after infarction. Results： Three days later, MSCs localized predominantly in the infarct region of heart rather than in the remote region. MSCs were also observed in spleen, lung and liver. At 4 weeks after infarction, echocardiographic parameters, including ejection fraction, fractional shortening, left ventricular end-diastolic and end-systolic diameters, were not significantly different between MSCs and saline groups. Hemodynamic examination showed that ± dp/dtmax were similar between MSCs and saline-treated animals. Histological evaluation revealed that infarct size and vessel density were not significantly changed by MSCs infusion. Conclusion： Intravenously injected MSCs can home to infarcted myocardium, but plays a limited role in cardiac repair following myocardial infarction.