Intravenous MSC Therapy on Ischemia-Reperfusion Injury in Patients With Myocardial Infarction

Inclusion Criteria: 1. Age between 18 and 75; 2. First performance of anterior acute ST-segment elevation myocardial infarction (STEMI), Killip grade 2 or below on admission; 3. Completing emergency percutaneous coronary intervention within 12h, with TIMI flow grade 0 or 1 (before stent implantation) and 3 (after stent implantation); 4. LVEF in echocardiography is 45% or below primary PCI. Exclusion Criteria: 1. Medical history of Q wave myocardial infarction, significant valve disease, pericarditis, pericardial tamponade, myocardiopathy, chronic heart failure or cardio embolism; 2. Non ST-segment elevation myocardial infarction; 3. Chronic occlusion in LCX or RCA besides LAD; 4. Diagnosed with severe coronary artery disease but not yet causing a loss of heart function; 5. Hemodynamic disorders, shock or respiratory failure on admission; 6. Atrial fibrillation with warfarin treatment only or at high risk of bleeding; 7. Constant tachycardia, malignant arrhythmia, complete atrioventricular block, new-onset complete left bundle branch block (LBBB) or pacemaker implantation; 8. Mechanical complications of acute myocardial infarction (interventricular septal defect, rupture of papillary muscle, etc.) or huge left ventricular aneurysm could only be corrected through surgical procedures; 9. Chronic pulmonary heart disease (COPD, bronchial asthma, chronic bronchitis, emphysema or pulmonary heart disease), autoimmune disease or patients on immunosuppressive therapy; 10. Acute infective disease; 11. Hepatitis B/C virus or HIV; 12. Blood system diseases (thrombocytopenia, severe anemia, leukemia, etc.); 13. Severe renal insufficiency, with creatinine clearance (CCr) \<33 ml/min or serum creatinine \>133 μmol/L; 14. Obvious abnormalities in liver function (ALT and AST 3 times higher than the upper limit of normal value); 15. Medical history of cerebral hemorrhage; 16. Medical history of the malignant tumor; 17. Cognitive impairment, dementia or severe mental illness (SMI); 18. Substantial disability negatively influenced regular follow-up research; 19. Systematic diseases not been effectively controlled or life expectancy \< 1 year; 20. Pregnant or lactating women; 21. Not suitable for MRI examination, or could not stick to treatment plans; 22. Could not or not willing to give written informed consent. Exit Criteria: 1. Intolerable infaust events or changed treatment strategy leading to serious violations of trial conduct; 2. Requiring to exit the clinical trial; 3. Research scheme violations, severely disrupted safety and effectiveness of the trail; 4. Lost to follow-up cases; 5. Conceiving children or want to do that during the treatment period; 6. Candidates not fit to carry on the trial.