Pycnogenol enhances proliferation and mineralization in osteoblast-like MC3T3-E1 cells

Pycnogenol (PYC) is a natural plant extract from the bark of Pinus pinaster Atiton that has potent anti-oxidant activities. Recent studies have shown that orally administered PYC can increase the biomechanical strength of bone and bone mineral density in ovariectomized rats. However, the effect of PYC on osteoblast mineralization has not yet been examined. We studied the differentiation and mineralization in mouse osteoblast-like MC3T3-E1 cells. PYC enhanced the metabolic activity dose dependently using an MTT assay by 120% (37.5 μg/ml) to 180% (375 μg/ml). The calcium depositions of the cells by alizarin red S staining were increased for 28 days after the culture with 375 μg/ml PYC. PYC activated the expression of estrogen receptor β (ERβ) about 2.8-fold for 28 days after the culture with 375 μg/ml PYC. These results suggest that PYC stimulates osteoblastic differentiation and mineralization via the expression of ERβ.