Abstract:

BACKGROUND: Numerous studies have demonstrated that chemotaxis or direct intramyocardial injection of bone marrow stem cells can differentiate into myocardial cells, vascular endothelial cells or vascular smooth muscle cells in vivo following myocardial damage.

OBJECTIVE: To observe distribution, growth and differentiation of bone marrow mesenchymal stem cells (BMSCs) transplanted by different methods in vitals.

METHODS: A total of 39 Japanese rabbits aged 3 months were selected to establish animal models of acute myocardial infarction, and then randomly divided into four groups. Three experimental groups were injected with BrdU-labeled autologous BMSCs through direct injection in myocardium, coronary artery injection and intravenous injection. The control group contained three subgroups, which were separately treated with an equal volume of saline through direct injection of coronary artery, vein and myocardium. At 4 weeks, animals were sacrificed to obtain heart, lung, liver and kidney to make tissue sections. BrdU-positive cells and BrdU- and α-striated muscle actin-positive cells were observed.

RESULTS AND CONCLUSION: ①BMSCs labeled with BrdU and BrdU + α-striated muscle actin were found in and surrounding the infarct in each experimental group. Some of them had been connected with host myocardium and each other, with obvious transverse striation and sarcomere. ②The density of blood capillary increased in each experimental group compared with the control group (P < 0.05). The effectiveness sequence was coronary artery injection group, myocardium injection group and vein injection group from good to poor. ③The cells labeled with BrdU were found in the liver, lung and kidney of two groups which were transplanted through coronary artery and vein. Moreover, numbers of BrdU-positive cells were more in the lung than in the liver and kidney of the vein injection group. But, they did not differentiate and there were no tumor cells. Results have suggested that all three transplanting methods can induce regeneration of myocardial cells and blood capillaries in and surrounding the infarct region. Except myocardium injection group, BrdU-positive cells can be determined in non-target organs, but still mainly expressed in target organs.