Phytoestrogen-rich Pueraria mirifica (PM) tuberous extract is a promising candidate for the development of anti-
osteoporosis drugs for postmenopausal women, but its action has never been validated in humans or in non-human primates, which are more closely related to humans than rodents. In vitro study of non-human primate osteoblasts is thus fundamental to prepare for in vivo studies of
phytoestrogen effects on primate bone. This study aimed to establish a culture system of baboon primary osteoblasts and to investigate the effects of PM extract and its
phytoestrogens on these cells. Primary osteoblasts from adult baboon fibulae exhibited osteoblast characteristics in regard to proliferation, differentiation, mineralization, and
estrogen receptor expression. They responded to 17β-estradiol by increased proliferation rate and
mRNA levels of
alkaline phosphatase (ALP),
type I collagen, and
osteocalcin. After being exposed for 48 h to 100 μg/ml PM extract, 1000 nM
genistein, or 1000 nM
puerarin, primary baboon osteoblasts markedly increased the rate of proliferation and
mRNA levels of ALP and
type I collagen without changes in Runx2, osterix, or
osteocalcin expression. PM extract,
genistein, and
puerarin also decreased the RANKL/OPG ratio, suggesting that they could decrease osteoclast-mediated
bone resorption. However, neither PM extract nor its
phytoestrogens altered
calcium deposition in osteoblast culture. In conclusion, we have established baboon primary osteoblast culture, which is a new tool for bone research and drug discovery. Furthermore, the present results provide substantial support for the potential of PM extract and its
phytoestrogens to be developed as therapeutic agents against bone fragility.