Experimental Study On The Effects Of Bone Marrow Stem Cells Mobilization On Infarcted Myocardium Repair And Grafted Vein Bridge Prognosis

Background: Coronary artery bypass graft can improve blood supply to infarcted myocardial areas and facilitate bone marrow stem cell mobilization. But the potency of bone marrow stem cells on infarcted myocardium repair is often omitted because there are only a few stem cells in the peripheral blood circulation. The feasibility of combined coronary artery bypass graft and bone marrow stem cell mobilization for ischemia heart disease treatment was studied in three parts.Part I. Objective: To investigate the pattern and the affecting factors of bone marrow stem cell mobilization after off-pump coronary artery bypass graft. Material and methods: According to experimental requirements, 36 cases of coronary artery disease were chosen for this study. The CD34+ cell counts were made by flow cytometer after off-pump coronary artery bypass. The increase of CD34+ cell counts can represent bone marrow stem cells mobilization indirectly. Results: There were a few CD34+ cells in the peripheral blood circulation in patients with coronary artery diseases before operation. The CD34+ cell counts significantly increased, peaking at 24 hours after operation, and turn back to pre-operation level at 48-72 hours after operation. There are highly positive correlations between CD34+ cell mobilization and serum myocardium enzyme and vascular endothelial growth factor.Part II. Objective: To further investigate the effects of bone marrow stem cell mobilization on infarcted myocardium and cardiac function. Material and methods: New Zealand rabbits, 24 cases, were divided equally into two groups at random. Acute myocardial infarction model was induced by ligating left anterior descending branch of coronary artery with 4-0 noninvasive medical sutures. In the test group recombinant human granulocyte colony-stimulating factor was given by subcutaneous injection 24 hours after operation, once per day in successive 10 days. In the control group saline was given in the same way. Bone marrow stem cell mobilization was reflected in karyote counts and mononuclear cell proportion in peripheral blood. Results: Acute myocardial infarction model was madesuccessfully by left anterior descending branch ligation. The ejection fraction of left ventricular in the test group was improved compared to control group, with decreased infarcted myocardial areas and increased small vessel density in the infarcted myocardial areas.Part III. Objective: To investigate the effects of bone marrow stem cell mobilization on grafted vein bridge prognosis and intima proliferation of anastomosis. Material and methods: New Zealand rabbits, 24 cases were divided equally into test group and control group at random. Cervical middle incision was made under general anesthesia. Bilateral vein bridges by end to side anastomosis were made to the common carotid arteries with 8-0 Dacron sutures. Vascular endothelium of one grafted vein bridge was digested by 0.5% trypsin. The way of bone marrow stem cell mobilization was the same as that in Part II. Results: The grafted vein bridges with intact endothelium had higher rate of patency, and the lower patent rate was seen in grafted vein bridges with complete endothelial denudation. The patent rate of the grafted vein bridges with complete endothelial denudation was 67% versus 30% between test group and control group. Pathological examination showed that there were various degrees of intima proliferation in all anastomosises of grafted vein bridges. The intima proliferation of anastomosis in grafted vein bridges with complete endothelial denudation was more severe than grafted vein bridges anastomosis with intact endothelium. In the test group reendothelization hi grafted vein bridges with complete endothelial denudation occurred completely and the anastomosis had relatively lower intima proliferation than that in the control group. Statistic analysis demonstrated that bone marrow stem cell mobilization and intact endothelium and their interaction might prove advantageous to reduce the degree of anastomosis intima proliferation.Concl...