At the small scale, bone structure is constantly remodeled throughout life. We lose bone mass and strength as we age, a condition known as osteoporosis, in part due to a systemic shift of the balance of activities between osteoclasts that remove bone structure and osteoblasts that create it. In older people there is too much absorption of bone and not enough bone deposition. Here researchers demonstrate a way to tilt that balance back towards a more youthful measure:
We recently reported that in vitro, engineered 50 nm spherical silica nanoparticles promote the differentiation and activity of bone building osteoblasts but suppress that of bone-resorbing osteoclasts. Furthermore, these nanoparticles promote bone accretion in young mice in vivo.
In the present study the capacity of these nanoparticles to reverse bone loss in aged mice, a model of human senile osteoporosis, was investigated. Aged mice received nanoparticles weekly and bone mineral density (BMD), bone structure, and bone turnover were quantified. Our data revealed a significant increase in BMD, bone volume, and biochemical markers of bone formation. Biochemical and histological examinations failed to identify any abnormalities caused by nanoparticle administration. Our studies demonstrate that silica nanoparticles effectively blunt and reverse age-associated bone loss in mice by a mechanism involving promotion of bone formation. The data suggest that osteogenic silica nanoparticles may be a safe and effective therapeutic for counteracting age-associated bone loss.