The Changes Of Ischemic Myocardium In Rabbits Before And After Mononuclear Bone Marrow Cells Implantation

Objective: To detect the changes of integrated backscatter (IBS) and regional motion function of the left ventricular in rabbits with ischemic myocardium before and after Mononuclear bone marrow Cells (MBMCs) implantation by echocardiography and also explored the value of MBMCs implantation in ischemic myocardium.Methods: Myocardium infarction were created in rabbits (n=36) by left anterior descending coronary artery (LAD) ligation,10 rabbits died because of pneumothorax or influence.26 rabbits were successfully created and lived 4 weeks after MBMCs implantation , divided them into two groups randomly: implantation group(n=12) and control group (n=14).All rabbits were evaluated by 2-dimensional echocardiography, Doppler tissue imaging(DTI)and integrated backscatter (IBS), on 1 day before operation,2 weeks after operation and 4 weeks after implantation . Examination were performed with a machine (Hewlett-Packard Sonos 5500, Andover, Mass) with a 2.5-MHz transducer. LV end-diastolic and end-systolic volumes and ejection fraction (EF) were determined from 2- and 4-chamber views by the Simpsons, biplane formula according to the recommendations of American Society of Echocardiography. Turn the machine settings to DTI-mode, the pulsed wave DTI was performed using the same apparatus. From the LV apical 2-chamber view, the Doppler sample volume (2-mm axial length) was placed in the middle and basal segment of the anterior wall LV. The following measurements were made from the pulsed wave DTI recording: The peak early diastolic velocity(Ve) and the peak systolic velocity(Vs) of the middle and basal segment of the anterior wall of LV. Then turn machine setting to IBS-mode, the echocardiography system with online acoustic densitometry software was used for 2-dimension IBS image acquisition and analysis. All studies were performed using the parasternal in aortic short-axis view, which is the best view in anterior of LV for IBS signal sensitivity, because both the IVS and PW are almost perpendicular to the transducer beam. For IBS analysis, an 11 - x11 -pixel elliptical region of interest was placed in middle segments of LV anterior wall in aortic short-axis view .The IBS analysis system allows the operator to acquire, store on an optical disk, and retrieve a sequence of continuous IBS images in a digital format with maximum dynamic range of 60 dB. Typically, about 60 image frames corresponding to 2 cardiac cycles were analyzed offline. The settings of the time-gain compensation levers were all equal(midrange) and the lateral-gain compensation was not used. From the time intensity curve corrected with a smoothing(noise-reduction) filter, we measured 2 IBS parameters: CVIB and All or IB. The CVIB was determined as the difference betweenpeak(end-diastolic) and nadir (end-systolic) IBS values. In this study, the AH of the pixels within the region of interest are represented as negative values after data normalization, that is, by subtracting the All of the adjacent pericardium from that of the LV myocardium. Every data measured 3 cycles, then obtained the average. Tissue was collected and Immunofluorescence was analyzed After finishing measurements.Results: (1) Ten rabbits were excluded because of death after operation. Echocardiography imaging of 26 rabbits were clear in 1 day before operation, 2 week after operation and 4 weeks after implantation. The sizes and systolic function of LV in 26 rabbits were normal before operation. (2) Two weeks after operation, the sizes of LV became larger, the anterior wall of LV became thinner and systolic range became weaker even disappeared. EF,CVIB, Vs and Ve was lower and All was higher in both groups than pre-operation (PO.05) . (3) Four weeks after implantation, compared with control group, LVDd was smaller and systolic range became larger, All descended. EF, Vs, Ve and CVIB increased (PO.05) .Conclusions: (1) MBMCs can subsist and become myocardium after implantation, which has been applied for the replacement of the infarcted myocardium to improve cardiac progenitor and improve the number of microvessels in ischemic myocardium. The regional motion function become faster and collateral circulation are improved in the Left Ventricular of Rabbits with Ischemic Myocardium after MBMCs Implantation. (2) TDI is a valid and sensitive method for detecting of regional Myocardium motion and cardiac function in ischemic myocardium after MBMCs implantation. (3) Integrated backscatter (IBS) can detect the changes and myocardial viable cell and collateral circulation development of rabbits with ischemic myocardium before and after MBMCs.