| Background:A fair mount of basic and clinical trials have shown that stem cell transplantation can improve cardiac function after myocardial infarction.As a kind of adult stem cells,BMSCs(bone marrow mesenchymal stem cells)have self-renewing and differentiation potential,which have been widely used in research on myocardial infarction since it is not limited by ethic and has rare rejection and tumorigenicity.However,its clinical application is limited by which a small number of cells migrate and locate in the infarcted myocardium and improve the heart function finitely,so,it has becomes one of hot spots in the treatment of stem cell therapy that how to improve the rate of stem cell transplantation and localization.TNC(Tenascin-C)is a glycoprotein in the extracellular matrix,which can promote adhesion,migration and differentiation of vanous cells in vitro by regulating adhesion between matnx and interacting with matrix.TLR-4(Toll Like Receptor 4)is a transmembrane glycoprotein that plays an important role in the immune response.BMSCs express TLR4 which can exert different effects on BMSCs by different pathways under the different oxidative stress conditions.TNC acts as a ligand of TLR4 and it is unclear whether they can interact with each other to have influence on proliferation,migration and differentiation of BMSCs after myocardial infarction.This research group has verified in vitro experiments at earlier stage that IOOug/ml TN-C can promote the migration of BMSCs and reduce the apoptosis-promoting effect of H2O2 on BMSCs when H2O2 used in simulation of microenvironment of myocardial infarction.Body micro environment after myocardial infarction is more complex,thus,it is not unclear that whether 100ug/ml TNC has a similar effect on BMSCs.Objective:TNC-/-mice after myocardial infarction are used as the research objects in this experiment based on the vitro experiments at earlier stage to be provided with BMSCs and the BMSCs preprocessed with the simulant of 100ug/ml TNC for the observation on influence of TNC on cardiac function and myocardium viability of TNC--/mice after treatment for myocardial infarction with BMSCs transplantationMethod:TNC-/-mice are used as the research objects of which BMSCs are extracted firstly for cultivation up to the 3-4th generation to identify the cell phenotype with flow cytometry to determine whether they are BMSCs;secondly,the model of acute myocardial infarction shall be prepared,of which caudal vein shall be injected with the BMSCs from TNC-/-mice and the simulant of TNC a week later and shall be killed to determine all the indexes.There are 4 groups in this experiment:? sham operation group(Shame group)(n=3):after anesthetized,the mice shall be operated to thoracotomy with anterior descending branch sutured but not ligatured;?PBS group(nd):after a week of successful modeling,the mice shall be injected with 0.1 mlPBS from caudal vein.? MSCS group(n=5):after a week of successful modeling,the mice shall be injected with 0.1ml MSCS(about 1×106)from caudal vein;:simulant group of MSCS+TNC(n=5):after a week of successful modeling,the mice shall be injected with MSCs preprocessed with the simulant of TNC(concentration of 100ug/ml)from caudal vein.Conditions of myocardial necrosis and myocardial fibrosis shall be determined with HE and MASSON trichrome staining method and the area of myocardial infarction shall be calculated with image pro plus,the image analysis software;cardiac color ultrasound shall be used to determine left ventricular systolic and LVEDV as well as LVEF;levels of IL-6,IL-12,TNF-? and TGF-? in peripheral blood of mice shall be determined with ELISA method.Results:results of HE and Masson trichrome staining show that both MSCs group(15.19%+1.88%)and the simulant group of MSCs+TNC(14.80%+1.71%)are able to reduce the area of myocardial infarction and degree of cardiac fibrosis compared with PBS group(19.42%±1.78%).However,improvement effects of the two group have no obvious difference(P>0.05);results of ultrasound show that MSCs group(54.38%+2.69%)and the simulant group of MSCs+TNC(57.73%+0.39%)group are able to improve cardiac function compared with LVEF(44.84%+2.67%)in PBS group.However,improvement effects of the two group have no obvious difference(P>0.05);results of ELIS A determination show that levels of IL-6,IL-12,TNF-? and TGF-? in peripheral blood of mice both in MSCs group and the simulant group of MSCs+TNC are lower than those of PBS group.However,no obvious difference(P>0.05)are discovered between them.Conclusion:In the absence of TN-C,BMSCs also have benefits on mice after treatment for acute myocardial infarction,which can improve the heart function,reduce infarct size and degree of myocardial fibrosis,at the same time decrease the level of inflammatory response in vivo.However,the BMSCs preprocessed with the simulant of TNC have the trend of improving heart function,but did not reach significant difference. |
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