The Influence Of Multiple Transplantation Intravenously On The Remodeling Of Cardiac Collagen Network After Myocardial Infarction By Human Umbilical Cord Blood Mononuclear Cells

Objective:To investigate the influence of multiple transplantation intravenously on the remodeling of cardiac collagen network after myocardial infarction by human umbilical cord blood mononuclear cells (HUMNCs)Methods:HUMNCs were harvested, cultured and expanded from umbilical cord blood of healthy full-term pregnant females. 60 Chinese rabbits were divided into four groups randomly. The sham operation group (n=15) was intravenously injected with normal saline 7d,9d, 11d,13d,15d after the non-ligation of the LAD. The control group (n=15), which had undergone ligation of the left anterior coronary artery (LAD), was intravenously injected with normal saline 7d,9d, 11d,13d,15d after operation. The single transplantation group (n=15) were intravenously injected with human umbilical cord blood mononuclear cells (HUMNCs) labeled with bromodexyuridine (BrdU) 7d after operation, and normal saline 9d, 11d,13d,15d after the ligation of the LAD. The multiple transplantation group (n=15) were intravenously injected with human umbilical cord blood mononuclear cells (HUMNCs) labeled with BrdU 7d,9d,11d, 13d,15d after the ligation of the LAD. Echocardiography examination was performed to measure left ventricular end-diastolic dimension(LVEDd) and left ventricular ejection fraction (LVEF) at 1 week,3 weeks and 5 weeks after operation. The rabbits were sacrificed for immunohistochemistry staining to identify the survival of transplanted cells (anti-BrdU monoclonal antibody), and for HE staining and Masson's trichrome staining to observe the structure of the cardiac collagen network.Results:(1) Transthoracic echocardiography at 1 week,3 weeks and 5 weeks after the operation showed a significant enlargement of left ventricular end-diastolic dimension (LVEDd) and left ventricular ejection fraction (LVEF) in the cell groups and the control group, compared to the sham operation group(P<0.01). At 3 weeks and 5 weeks after the operation, the both cell transplatation groups showed a less enlargement of left ventricular end-diastolic dimension (LVEDd) and less reduction of and left ventricular ejection fraction (LVEF), compared to the control group (P<0.05), and while the heart function of the multiple transplantation group was improved compared with the single transplantation group at 5 weeks after the operation (P<0.05).(2) The BrdU positive cells were found in the peri-myocardial infarction area in the both transplantation groups, and while the number of the BrdU positive cells in the multiple transplantation group are more than that in the single transplantation group. Masson's trichrome staining showed that collagen fibers were arranged regularly in the myocardial tissue of the sham operation group's rabbits at 3 and 5 weeks after operation. Compared to the sham operation group, the counts of the collagen fiber in the control group and the cell transplatation groups were significantly increased at 3 weeks after the operation, and the collagen fibers were fused partially, and arranged irregularly, the basic structure of myocardium was destroyed. The collagen fibers in the multiple cell transplantation group were arranged more regularly, compared to in the single group.Conclusion:(1) The human umbilical cord blood mononuclear cells (HUMNCs) delivered by intravenous injection could migrate to the infarct region and survive in the peri-myocardial infarction area, and the number of the transplanted cells in the myocardium in the multiple transplantation group was increased, associated with more improvement of the heart function, compared to the single transplantation group.(2) The single and multiple intravenous transplantation of human cord blood mononuclear cells could reduce the collagen deposition and integration of the collagen fuse, and promote orderly arrangement of myocardial collagen network in the myocardial infarction region. Compared with the single-cell transplantation group, the multiple cell transplantation group further improved.(3) The multiple intravenously transplanted cord blood mononuclear cell transplantation for myocardial infarction was superior to improve cardiac function and inhibit myocardial collagen remodeling, compared to single intravenously transplanted human cord blood mononuclear cells.