Possible mechanism of the stimulatory effect of Artemisia leaf extract on the proliferation of cultured endothelial cells: involvement of basic fibroblast growth factor

To investigate the possible mechanism of the stimulatory effect of a hot water extract from Artemisia leaf (Artemisia princeps PANPANINI) (AFE) on the proliferation of endothelial cells, cells from bovine aorta were cultured for 72 h in RPMI1640 medium supplemented with 10% fetal calf serum in the presence of 5 micrograms/ml AFE. The AFE treatment significantly increased the cell number after culture, while in the presence of 10 micrograms/ml unfractionated heparin, AFE conversely decreased it. This implied that AFE enhanced the cell growth promotion by basic fibroblast growth factor (bFGF). The accumulation of bFGF was significantly increased in the culture medium, in the low-affinity (glycosaminoglycans-binding) fraction, and in the cell extract fraction, but was unchanged in the high-affinity (receptor-binding) fraction. The contents of 35S]sulfate-labeled glycosaminoglycans in both cell layer and the medium were not increased by AFE treatment. The proliferation of A10 cells, an established cell line of smooth muscle cells from murine aorta, was not stimulated by AFE. A10 cells did not produce a significant amount of bFGF in the presence or absence of AFE. Thus, the production of bFGF was considered to be involved in AFE stimulation of cell proliferation. In conclusion, it was suggested that AFE stimulated endothelial cell proliferation by increasing the production of bFGF rather than by an increase in the number of bFGF receptors and the content of glycosaminoglycans in the cell layer. The enhanced reserve of bFGF in the low-affinity fraction of cell layer and in the medium would cause the AFE-stimulated proliferation of endothelial cells.