Comparison Of Efficacy Of Bone Marrow Derived Mesenchymal Stem Cells And Bone Marrow Mononuclear Cells Via Percutaneous Intra-endocardial Delivery In Porcine Myocardial Infarction Hearts

BackgroundIt is widely agreed that the regenerative capacity of human myocardium is grosslyinadequate to compensate for the severe loss of heart muscle presented by catastrophicmyocardial infarction or other myocardial diseases. Compensatory hypertrophy of thesurviving cardiac myocytes and fibrosis of the infarcted myocardium lead to adverseremodeling and finally congestive heart failure. Although the rapid development of drugtherapy and interventional treatment has significantly reduced mortality in patients with myocardial infarction, the cardiac myocytes loss remains，which lead to unsatisfactoryprognosis in many patients. Heart transplantation, as a terminal treatment, is also limitedby immunologic rejection, lack of donor, high mortality and high expense.Stem cells are a class of relatively undifferentiated cells that retain the ability todivide and proliferate throughout postnatal life to provide progenitor cells that candifferentiate into specialized cells. They bring a new alternative for the treatment ofmyocardial injury. Stem cell therapy for myocardial infarction has received widespreadattention. Numerous studies have shown that stem cells can play a therapeutic role ofmyocardial injury in a variety of ways. The basic, pre-clinical and clinical studies haveconfirmed the safety and efficacy of stem cells for cardiac repair. Two cell types havecompleted phase-III clinical trials: skeletal myoblasts and bone marrow mononuclearcells.However, the most beneficial cell type for the treatment of myocardial infarction isuncertain. Studies in patients with acute myocardial infarction (AMI) have shown mixedresults, and the huge variability in the technical procedures used in each study madecomparison difficult. Therefore, we conducted a study to compare functional andstructural recovery after AMI in pigs after trans-endocardial injection of bone marrowmononuclear cells (BMMNCs) versus mesenchymal stem cells (MSCs).Aims1. To establish a trans-endocardial method to treat AMI of large animals.2. To compare the efficacy of BMMNCs and MSCs trans-endocardial injection oncardiac functional improvement in porcine myocardial infarction hearts.3. To investigate the potential mechanisms.Methods1. BMMNCs and MSCs were isolated by density centrifugation and in vitro cultured,characterized and fluorescent labeled.2.30mini-pigs were divided into3groups randomly (BMMNCs, MSCs, CON).Myocardial infarction was induced by60-min balloon occlusion of the left anterior descending artery, followed by reperfusion.3. Two weeks after myocardial infarction, CM-DiI labeled BMMNCs and GFP labeledMSCs and medium were trans-endocardial injected into the border and central zone ofthe infarct.4. Heart function and myocardium perfusion were assessed by SPECT andechocardiography for8weeks.5. All the animals were sacrificed at10weeks. Cell engraftment, proliferation anddifferentiation were examined by immune-fluorescence staining.6. Vascular density was determined by CD31staining.7. Left ventricular remodeling was evaluated by Sirius red staining.8. MMP-2and MMP-9were detected by western blot.Results1.8animals died during the MI induction. The remaining22animals survived until theend of the experiment. There were8,7,7animals remain in MSCs, BMMNCs, CONgroup respectively. The mean number of cells implanted was245×106and56×106inBMMNCs and MSCs group, respectively. Injection of the cells or medium was notassociated with any death.2. At week10, there was no significant difference in LVEF, LVESV, and LVEDVbetween three groups by echocardiography (for LVEF, MSCs:51±8.3%, BMMNCs:50±6.2%, CON:48±7.3%, p>0.05). When compared with week2, although LVEFin animals treated with both BMMNCs and MSCs showed increase, there was nosignificant change found (p>0.05). At week10, WMSI improved only in MSCs whencompared with week2(1.96±0.24vs2.35±0.21, p<0.05). WT%also significantlyimproved in animals that received MSCs (27±4.4%vs18±3.7%, p<0.05)，andWT%in MSCs was superior to that in BMMNCs and CON at week10(27±4.4%vs20±2.1%,18±2.9%, p<0.05).3. When compared with week2, animals treated with both MSCs and BMMNCs showedsignificant reduction in the area of myocardium with perfusion defect at week10 (MSCs：21.7±3.0%vs29.6±5.1%，p<0.05；BMMNCs：22.9±3.7%vs29.4±5.6%，p<0.05) as defined by the quantitative SPECT analysis. At week10, Absolute changedmyocardial perfusion defect were also significantly greater in the MSC and BMMNCgroups than that in the CON group (-8.0±2.5%，-6.5±1.9%vs.-2.0±1.3%，p<0.05).4. At week10, immunofluorescence staining for CD31antibody indicated significantneovascularization in stem cell-treated hearts, with more CD31-expressing vesselsbeing present in peri-infarct regions of cell-treated compared with medium-treatedhearts.5. MSCs transplant was associated with a decreased fibrosis (collagen vascular fraction)compared with BMMNCs and CON（55.4±6.5%vs63.6±7.8%，67.4±7.2%，p<0.05）.6. Western blot analysis showed that myocardial content of MMP-2significantlydecreased in the MSC group only (p<0.05). There was no significant difference ofMMP-9between3groups.Conclusions1. We established a trans-endocardial method to treat AMI of large animals andconfirmed its feasibility.2. Both BMMNCs and MSCs improved myocardial perfusion and MSCs improvedregional function of left ventricle of heart.3. MSCs might be more effective than BMMNCs for the repairing of acute myocardialinfarction via percutaneously intramyocardial injection, and the cause of thedifference might be the inhibitive effect on fibrosis of MSCs.