Abstract
An effective method for preventing bone loss is by promoting osteoblast
differentiation and bone formation. While dexamethasone has been routinely
used as a classical inducer for osteoblast differentiation, limitations have
been observed with its usage, including its varied effects on expression of
osteoblast genes in different species and its potentials in suppressing
osteoblastic differentiation and mineralization. In this study, we assessed
the ability of flavonoid icariin in enhancing differentiation and
mineralization of cultured rat primary osteoblasts in the absence of
dexamethasone. It was found that, compared to the non-stimulated control,
icariin at 10−5 M produced a higher alkaline phosphatase
activity, more and larger areas of alkaline phosphatase-positive colonies
(CFU-FALP) and mineralized nodules, more osteocalcin
secretion and calcium deposition, higher levels of mRNA expression of
alkaline phosphatase, osteoblastic transcription factors osterix and
runt-related transcription factor 2, and collagen 1α, higher levels
of protein expression of collagen 1α, alkaline phosphatese, osterix,
and runt-related transcription factor 2. In addition, icariin at
10−5 M was always more potent than dexamethasone at its
optimal concentration of 10−8 M on the above osteoblast
differentiation and mineralization markers. Taken together, our studies
demonstrated that icariin has a pronounced ability in promoting osteoblast
differentiation in vitro in the absence of dexamethasone.
Key words
osteoblasts - differentiation - icariin - proliferation - dexamethasone