The Effect Of Bone Marrow Mesenchymal Stem Cells On The Metabolism Of Fatty Acid Of Hypertrophic Cadiocyte In Vitro

Background Stem cell transplantation promises an effective way in treatment for heart diseases, mesenchymal stem cells (MSCs) become the most fascinating scenes because these cells have characters of originating conveniently, expanding easily, and low immunity. Although many problems about the effect of MSCs on cardiomyocytes have yet to be determined, the good results in treating myocardial infarction and cardiomyopathies of animals have paved its ways into clinical trials. At the same time, basic research must provide more details so that we can use it more safely, effectively and rationally. The research indicated the myocardial ischemia(MI) and remodeling were company with the change of cardiomyocytes metabolism. The research on the mechanisms of MSCs improving cardiac functions explained MSCs can differentiate into contractile cells in host myocardium repairing injured cardiac muscle organization and reduce cardiac muscle organization fibrosis. The influence on the fatty acid metabolism of host myocardium has not yet to be reported. We focous on the fatty acid metabolism and sarcomeric structure of cardiomyocytes co-cultured with MSCs.Objectives To simulate cardiomyopathy and the microenvironment of cell transplantation by use of the model of hypertrophy and the system of co-culture, to observe the structure of the cardiomyocytes co-cultured with BMMSCs and to detect some duplication factors and the content of intracellular free fatty acids. To disclosure the effect of bone marrow mesenchymal stem cell (MSCs) on host myocardium in the metabolism of fatty acid and find some mechanism of MSCs transplantation improving the heart functions.Methods1. MSCs were isolated from thighone and tibia of Wistar rats , purified by adheresion-screening method, and expanded in vitro. Cardiomyocytes were isolated from heart of neonatal Wistar rats by enzymatic digestion, purified by differential adhesion method and these cells were treated with bromodeoxyuridine (Brdu) for 2 days.2. Simulation of cardiomyopathy based on hypertrophy cell model with AngⅡstimulating. Simulated the microenvironment of cell transplantation by co-culture using mesenchymal stem cells and neonatal rat cardiomyocytes with inset culture dishes.3.Neonatal cardiomyocytes cultured in vitro were assigned into 4 groups:a cardiomyocytes pre-treated with angiotensin(Ang)Ⅱco-cltured with MSCs group (co-culture group-1, n=5) , an Ang-Ⅱstimulating cardiomyocytes co-cultured with MSCs group(co-culture group-2, n=5),an AngⅡstimulating group (n=5) and a Normal control group (n=5). The changes of morphology of cardiomyocytes were observed under light microscope and immunofluorescence microscope. The activity of nuclear factor (NF)-κB and peroxisome proliferators-activated receptor (PPAR)α,PPARγwere detected by immunocytochemistry. We detected the content of intracellular free fatty acids by ultraviolet spectrophotometry.4. Sarcomeric structure was also observed through the detection of titinZ of normal neonatal cardiomyocytes by immunofluorescence.Results1. The significant up-regulation of NF-κB activation was observed in cardiomyocytes with AngⅡstimulating compared with nomal group(P<0.05)and the significant down-regulation of activation PPARγand PPARαwere observed (P <0.001 and P <0.01) . The concentrations of intracellular free fatty acids of cardiomyocytes in AngⅡstimulating group were significantly increased compared with nomal group(P <0.01).2. The significant down-regulation of NF-κB activation (P<0.001)and intracellular free fatty acids concentrations (P<0.001)were observed in Co-culture group-1 compared with AngⅡstimulating group. But the activation of PPARαand PPARγsignificantly were up-regulated compared with AngⅡstimulating group(P <0.05 and P <0.01). 3. In co-culture group-2, the activation of NF-κB is weaker compared with AngⅡstimulating group(p<0.05)and the activation of PPARγis stronger compared with i(tP <0.05). There were insignificant differences in the activation of PPARαbetween co-culture group-2 and AngⅡstimulating group(P >0.05). The concentration of intracellular free fatty acid of co-culture group-2 is lower than it of AngⅡstimulating group.4. Compared with normal control group,the cardiomyocytes in AngⅡstimulating group were absenct of the normal structure of the sarcomere. There were not significant differences between AngⅡstimulating group and Co-culture groups.Conclusion MSCs may improve the fatty acid metabolism of cardiomyocytes. This may be one of mechanisms of MSCs transplantation improving heart function possibly. There is no evidence proving that sarcomeric structure of cardiomyocytes which already damaged can be repaired by MSCs in short time.