The Influence Of Mesenchymal Stem Cell Transplantation On Cardiac Function And I_Na Of Ventricular Myocytes In Young Dilated Cardiomyopathy Rat

Objective:To investigate the influence of bone marrow mesenchymal stem cell transplantation on cardiac function and sodium channel current（INa）of ventricular myocytes on ventricular myocytes in young doxorubicin-induced dilated cardiomyopathy（DCM） rats. Then recording the L-type calcium channel current(I_Ca-L) of ventricular myocytes in normal young rats.Methods:1.Established the model of young DCM rat, evaluate the cardiac function and myocardial histology change: Forty SD rats of two-week-old were randomized divided into DCM group（n=20） and control group（n=20）.Dilated Cardiomyopathy was induced by intraperitoneal injection of doxorubicin 1mg/kg twice a week for six weeks, control group received the same dose volume injection of normal saline. HE stain was use to observe the myocardial histology change of the rats. Ultrasonic cardiogram（UCG）was use to evaluate the cardiac function of each groups2.Evaluation of INa of the young DCM rats: Single ventricular myocyte was isolated from rat heart by enzymatic dissociation, patch clamp technique was used to record the changes of INa in the left ventricular myocytes.3.The influence of mesenchymal stem cell transplantation on cardiac function and sodium channel current of ventricular myocytes in young dilated cardiomyopathy rat: Seventy-five SD rats of two-week-old were randomized divided into five groups: Normal（n=15）、Normal+MSC（n=15）、DCM（n=15）、DCM+PBS（n=15）、DCM+MSC（n=15）. Rats in MSC groups were treated with BMMSCs injection on anterior wall of left ventricular.Four weeks after transplantation, we used fluorescence microscope to observe the transplanted BMMSCs, and UCG was use to evaluate the cardiac function of each groups, patch clamp technique was used to record the changes of sodium channel in the left ventricular myocytes.4.Evaluation of I_Ca-L of the normal young rats: Use patch clamp technique was used to record the I_Ca-L、I-V curve、activation process、inactivation process and recovery process in the left ventricular myocytes of normal young rats.Result:1.The pathological detection showed that the myocardial structure of the DCM rats was badly injured, myocardium had a disordered and loosearrangement, cardiomyocytes showed edema, some of the myocardial fibers were dissolve and fracture, while the myocardial structure of control group rats showed no damage; The UCG results showed: the left ventricular ejection fraction（LVEF） and the left ventricular fractional shortening（LVFS） of DCM group rats were lower than control group, while the left ventricular internal dimension systolic（LVIDs） and the left ventricular internal dimension diastolic（LVIDd） increased in DCM group than in control group（P<0.05）.2.The INaof DCM group was potential-dependently reduced, the I-V curve was shifted to upward, and the INa current density in ventricular myocytes was significantly lower in DCM rats than in control rats（47.37±4.118 p A/p F vs. 64.31±3.278 p A/p F,P=0.0025）.DCM inhibited the steady-state activation. The half activation potential was raised in DCM rats than in control rats（-48.441±0.966 m V vs.-55.132±0.945 m V,P=0.000）. DCM accelerated the inactivation process. The half inactivation potential was lower in DCM group rather than control group（-98.49±1.152 m V vs.-90.70±1.983 m V,P=0.0031）. The recovery process of INa was unchanged.3. Four weeks after transplantation, the well-grown transplanted BMMSCss were found around the injiection point or the needle path; the cardiac function of DCM+MSC group was better than DCM and DCM+PBS groups（P < 0.05）, the cardiac function of DCM+MSC groupwas improved after transplantation（P<0.05）; Compared with DCM group and DCM+PBS group, the I-V curve shifted to downward, the INa current density was higher, the steady-state activation was accelerated and the steady-state inactivation process was slower（P<0.05）.4.The patch clamp results showed that the peak I_Ca-L density was（10.45±1.719）p A/p F, the half activation potential was（-17.27±2.276）m V, the half inactivation potential was（-12.70±1.672）m V, the recovery time（t） was（1740.57±650.610）ms.Conclusion:1.Young DCM rat model could be induced successfully in the doxorubicin injected way of this research, this model was confirmed by pathyology and UCG detection.2.Doxorubicin- induced DCM was significantly decreased INacurrent density, inhibited the steady-state activation. and accelerated the inactivation, These changes might lead to arrhythmia in DCM.3.BMMSCs transplantation could increase the cardiac function of DCM rat, accelerate the activation process and slow the inactivation process, increase the INa, reduce the damage of sodium channel. So BMMSCs transplantation might have some beneficial effect on young rat’s DCM.