Mononuclear cells isolated from mobilized bone marrow differentiate into vascular endothelial cells and cardiomyocyte-like cells / 中国组织工程研究

ABSTRACT

BACKGROUND:It is controversial whether bone marrow mobilization can retain in cardiac injured position in congestive cardiomyopathy or differentiate into cardiomyocytes and vascular endothelial cells. OBJECTIVE:To study the effects of granulocyte colony stimulating factor (G-GSF) on myocardium and angiogenesis in rats with congestive cardiomyopathy. METHODS:Fifty Wistar rats with heart failure caused by adriamycin-induced cardiomyopathy were divided into heart failure group (n=20) treated with normal saline and bone marrow mobilization (n=30) treated with subcutaneous injection of recombinant human G-GSF. Ten rats from the bone marrow mobilization were kil ed at day 6 of mobilization, and myocardial tissue was taken for CD43 immunofluorescent staining. Blood samples were taken from the rat tail in each group before and 5 days after treatment to count total number of white blood cells and percentage of mononuclear cells. Meanwhile, mononuclear cells extracted from the peripheral blood were used for flow cytometry detection. At day 5 after treatment, bromodeoxyuridine (BrdU, 50 mg/kg) was successively given to al rats for 4 weeks before they were sacrificed. Myocardial tissues were taken to determine the homing of mononuclear cells and evaluate differentiation of mononuclear cells into cardiomyocytes and vascular endothelial cells using BrdU staining, BrdU/myosin heavy chain double staining, and BrdU/actin double staining. Hematoxylin-eosin staining was used for determination of blood vessel density. RESULTS AND CONCLUSION:G-CSF mobilization increased the number of mononuclear cells that was significantly higher than before treatment (P<0.05). Flow cytometry showed that the number of CD34-positive mononuclear cells in the peripheral blood was higher in the bone marrow mobilization than in the heart failure group (P<0.05). Myocardial CD34 immunofluorescence showed that the heart failure group was negative and the bone marrow mobilization group was positive. In the bone marrow mobilization group, the myocardial tissue was positive for BrdU staining, BrdU/myosin heavy chain double staining and BrdU/actin double staining, while vascular endothelial cells in the region of myocardial injury was positive for BrdU;conversely, the heart failure group was negative. The density of blood vessels in the bone marrow mobilization group was significantly higher than that in the heart failure group (P<0.001). These findings indicate that bone marrow mobilization increases the number of mononuclear cells, and these cells are homing to myocardial injury, thereby playing a repair role in the myocardium and vascular tissue of heart failure rats with congestive cardiomyopathy.