Abstract
BACKGROUND The formation of new blood vessels, known as angiogenesis, is critical for recovery from ischemic heart disease, and estrogen is considered an important factor in this process. Here, we investigated the effects of 17β-estradiol (17β-E2) on proliferation and migration of cardiac microvascular endothelial cells (CMECs) in vitro. MATERIAL AND METHODS Rat CMECs were isolated and cultured with 17β-E2 (0.001-1 µmol/l) in the absence or presence of the estrogen antagonist tamoxifen. Then, the expression level of estrogen receptor alpha was evaluated by using immunofluorescence assay, RT-PCR, and Western blot. Cell proliferation was detected by methyl thiazolyl tetrazolium analysis and the cell migration was verified by a scraping assay and quantified by a Transwell chamber assay. CMEC differentiation was examined using a tube formation assay. Vascular endothelial growth factor (VEGF) secretion was detected by enzyme-linked immunosorbent assay. RESULTS CMECs exhibited homogenous, polygonal, exhibited contact inhibition, and had characteristically ovoid nuclei with 1 or 2 nucleoli, and the cytoplasm exhibited red fluorescence after staining for von Willebrand factor. 17β-E2 treatment upregulated estrogen receptor alpha expression in CMECs. 17β-E2 treatment significantly promoted the proliferation, migration, tubular structure formation, and VEGF secretion in CMECs. The maximal proliferation occurred in the presence of 0.01 µmol/l 17β-E2. Furthermore, estrogen and VEGF were found to synergistically stimulate angiogenesis. CONCLUSIONS Our data show that 17β-E2 promotes angiogenesis in vitro and suggests that estrogen treatment as a novel therapeutic modality in the management of arterial insufficiency.