| 권진숙¹, 정일하¹, 김유경¹, 박노관¹, 황경국¹, 배장환¹, 김동운¹, 고규영² , 조명찬² |
Backgrounds and Objectives: Previously, we reported that direct injection of COMP-Angiopoietin 1 (COMP-Ang 1) protein effectively attenuated ventricular remodeling in a rat model of myocardial infarction. In our unpublished data, COMP-Ang 1 is able to be delivered directly, via a non-Tie-2 pathway, to the cardiomyocytes. For the functional augmentation of adult stem cells such as BM-derived mesenchymal stem cells (BM-MSCs) and endothelial progenitor cells (EPCs), COMP-Ang 1 is an effective and valuable candidate, because of Tie-2 expressions in both hematopoietic stem cells and EPCs and of the possible effects via a non-Tie-2 pathway. Tie-2 expression of BM-MSCs and the effect of COMP-Ang 1 to BM-MSCs were not established. We investigate the direct effect of COMP-Ang 1 protein to BM-MSCs and the functional improvement under the hypoxic condition. Methods: To evaluate the direct effect or delivery of COMP-Ang 1 protein, rat BM-MSCs were incubated with COMP-Ang 1 protein (700 ng/ml) for 30 minutes at normoxic condition. COMP-Ang 1, including FLAG reporter protein, was pre-labeled with anti-FLAG FITC antibody. COMP Ang-1 (+) cells were evaluated by immunocytochemistry, 3-D confocal image analysis. Quantitative analysis of COMP-1(+) cells was evaluated by FACS analysis. And then to evaluate the functional improvement, BM-BMCs, pretreated with COMP-Ang 1 (50ng/ml), were incubated for 24 hours under hypoxic condition (under 1% O2). Quantitative analysis of apoptosis was evaluated by FACS analysis. Results: 1) COMP Ang-1-FITC florescence particles were observed with intracytoplasmic scatter pattern in BM-MSCs, especially active proliferative stage of BM-MSCs. The proportion of COMP Ang-1(+) cells by FACS analysis was 5.39±0.56 %. 2) Hypoxia-induced apoptosis of BM-MSCs were significantly reduced by FACS analysis (12.3 vs 9.2%). Conclusions: Although the precise mechansim of delivery is not elucidated in our study, COMP Ang-1 protein is directly delivered into rat BM-MSCs and reduces the hypoxia-induced apoptosis. This finding suggests COMP-Ang 1 is an effective and valuable candidate for functional augmentation of BM-MSCs.
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