Effect Of Bone Marrow Mesenchymal Stem Cell Transplantation On NF-κB Signaling Pathway In Rabbits After Acute Myocardial Infarction

Background:Myocardial ischaemia, neuroendocrine activation, inflammation reflex and cardiac overload after acute myocardial infarction which lead to myocardial cell necrosis, apoptosis and ventricular remodeling are important reasons of heart failure and arrhythmia. Therefore, reducing myocardial apoptosis, regulating neuroendocrine factors and inhibiting inflammatory response to improve ventricular remodeling may become one of the main mechanisms of myocardial infarction treatment, heart failure and arrhythmia prevention.Nuclear transcription factor-kappa B (NF-κB) is one of the key factors of cell gene transcription regulation. Recent studies showed that in the cardiovascular system, there is also NF-κB activation which can regulate apoptosis-related genes(bcl-2/bax,Capase3,p53,etc.), inflammatory cytokines(TNF-alpha,IL-1,IL-6,etc.),adhesion molecules (IC AM-1,VCAM-1),matrix metalloproteinases(MMPs) affecting myocardial cell damage and apoptosis.Thus,NF-κB pathway plays an important role in apoptosis, inflammation and ventricular remodeling after AMI.Bone marrow mesenchymal stem cells (MSCs) is a class stem cells with strong proliferation ability and multi-differentiation potential. In certain circumstances, MSCs not only differentiated into myocardial cells, but also secreted large amounts of growth factors and cytokines; meanwhile it can increase bcl-2gene expression to interfere cardiac myocyte apoptosis affecting cardiac function. But whether transplantation of MSCs in treating AMI by the impact NF-κB function is still unknown. And, there were no reports on MSCs transplantation affect NF-κB signaling pathway after myocardial infarction.Objectives:To investigate the expression of NF-κB p65, bax and TNF-alpha mRNA in myocardial tissue and the changes of myocardial cells apoptosis and the impact of bone marrow mesenchymal stem cell transplantation.Methods:Before this study, our research team have successfully established a model of myocardial infarction, cultured bone marrow mesenchymal stem cells and transplanted stem cells into myocardial infarction zone. And the rabbits are divided into normal control group (Nor group), sham operation group (SH group), myocardial infarction group (MI group) and MSCs transplantation group (MSCs group).we took surrounding tissues already prepared near infarction and detected apoptosis index by using TUNEL method, measured the expression of NF-KBp65and Bax protein in myocardial tissue by using immunohistochemical staining, and detected the expression of NTF-αmRNA in myocardial tissue by using in situ hybridization.Result:(1)By using immunohistochemical staining method, NF-κBp65and Bax expressions reduced in both Nor group and SH group, while compared with the Nor group and SH group, the expression of NF-κB p65and Bax were significantly increased (p <0.001) in the surrounding tissue near infarct of MI group and MSCs group.(2) Detection of TNF-amRNA by using in situ hybridization method, compared with the Nor group and SH group, MI group and MSCs group were more increased (p<0.001); and MSCs group was decreased than MI group (p<0.001).(3) By using TUNEL assay detect apoptosis, in MI group and MSCs group, apoptosis index was significantly greater than the normal group and sham group (p<0.001);myocardial cell was measured, however the apoptosis index of the MSCs group was significantly smaller than the MI group (p<0.001).Conclusion:After myocardial infarction, NF-κB signaling pathway was activated which can upregulate the expression of NF-κBp65, Bax and TNF-αmRNA; increase myocardial apoptosis. Transplantation of allogeneic MSCs can inhibit the activation of this signaling pathways and down-regulate expression of NF-KBp65、Bax and TNF-amRNA and reduce cardiac myocyte apoptosis.