Stimulation of osteoblastic differentiation and mineralization in MC3T3-E1 cells by yeast hydrolysate

In a previous study, it was reported that yeast hydrolysate (YH) was effective in promoting bone growth in Sprague-Dawley (SD) rats. To further clarify the mechanism of YH, the effects of YH on proliferation, differentiation and gene expression in vitro were investigated using osteoblastic cell lines (MC3T3-E1). Cell proliferation increased significantly as much as 110% of the basal value when cells were treated with 100 μg/mL of YH. Alkaline phosphatase (ALP) activity increased significantly with a YH concentration of 25-100 μg/mL, and the activity increased 152% that of the control at 100 μg/mL. The calcium content increased as much as 129% at 100 μg/mL YH. The gene expression levels of ALP and collagen type II (COL II) significantly increased approximately 1.3-fold and 1.7-fold of control, respectively, at 100 μg/mL. YH increased significantly the mRNA level of bone sialoprotein (BSP) but not in a dose-dependent manner. The mRNA levels of bone morphogenetic proteins (BMP)-2, BMP-4, collagen type I (COL I) and osteonectin (ON) did not increase. In summary, YH increased the proliferation of osteoblasts and directly stimulated ALP and bone matrix proteins (e.g. BSP, COL II), and these increases trigger osteoblastic differentiation (e.g. mineralized nodule formation).