Abstract 14025: Microvesicle-mediated Transfer of Mirnas Between Macrophages and Vascular Cells
Background: Intercellular communication plays a key role between inflammatory and vascular cells during the development of atherogenic plaques. A recently observed mechanism of interaction between non-adjacent cells is the exchange of microRNAs (miRNAs) by microvesicles. The influence of miRNAs during the development of atherosclerosis still remains elusive. Here, we report the microvesicle-mediated transport of miRNAs between macrophages and endothelial cells.
Methods/Results: Human monocyte cells (THP-1) were cultivated in microvesicle-depleted fetal calf serum (FCS) for 48 h. Cells were stimulated by phorbol myristate acetate (PMA) and lipopolysaccharides (LPS) whereas unstimulated cells served as controls. Cells and cell debris were removed by centrifugation. Microvesicles were pelleted by a second centrifugation (40.000g/2h; Beckman J2-HC). Western blot analysis showed exosomal specific proteins TSG101, ALIX und CD63. Vesicles between 25 and 90 nm in size were observed by electron microscopic analysis. MiRNA-screeing using qPCR arrays showed that exosomal release of miR-146a and miR-92a is specifically high, making them rank among the 5 most abundant miRNAs present in microvesicles. To test the transfer between macrophages and endothelial cells, fluorescently labeled miRNA was transfected into THP1 and co-cultivated with human umbilical venous cells using an in vitro co-culture system. Fluorescently labeled miRNA was found in endothelial cells and confirmed intercellular transfer of miRNA by co-cultivation.
Conclusion: These results demonstrate that activated monocytes secrete miRNAs via exosomes, especially miR-146a and miR-92a, and deliver them into endothelial cells. Selective packaging of miRNAs into vesicles may be crucial for the specificity of the biological functions of secreted miRNAs in pathological conditions like atherosclerosis. Thus, modulating miR-146a and miR-92a expression and its secretion by microvesicles may represent a novel approach for the prevention and treatment of vascular diseases.
- © 2013 by American Heart Association, Inc.