Stimulatory effect of menaquinone-7 (vitamim K-2) on osteoblastic bone formation in vitro

Menaquinone-7, which is vitamin K-2 (menatetrenone) with seven isoprene uni ts, is highly contained in the fermented soybean. The effect of menaquinone -7 (MK-7) on osteoblastic bone formation was investigated. Femoral-diaphyse al and metaphyseal tissues of young male rats (4 weeks old) were cultured f or 48 h in a medium containing either vehicle or MK-7 (10(-7)-10(-5) M). Ca lcium content, alkaline phosphatase activity, and deoxyribonuclic acid (DNA ) content in the diaphyseal and metaphyseal tissues was significantly incre ased in the presence of MK-7 (10(-6) and 10(-5) M). The effect of MK-7 in i ncreasing the diaphyseal and metaphyseal calcium content and alkaline phosp hatase activity was completely prevented in the presence of cycloheximide ( 10(-6) M), an inhibitor of protein synthesis. Moreover, osteoblastic MC3T3- E1 cells after subculture were cultured for 24 h in a serum-free medium con taining MK-7 (10(-7)-10(-5) M). Protein content, alkaline phophatase activi ty, osteocalcin and DNA content in the cells was significantly increased in the presence of MK-7 (10(-6) and 10(-5) M). The effect of MK-7 in increasi ng protein content, alkaline phosphatase activity, and osteocalcin producti on in the cells was completely blocked by cycloheximide. This study demonst rates that MK-7 has an anabolic effect on bone tissue and osteoblastic MC3T 3-E1 cells in vitro, suggesting that the compound can stimulate osteoblasti c bone formation.