Abstract
3D cell culture studies more accurately represent the complex in vivo mechanical environment of human bone and are, thus, superior to 2D studies when testing the efficacy of osteoporosis therapies. As such, the objective of this study was to use a 3D model to investigate the effect of sclerostin antibodies. Sclerostin is a protein, which inhibits osteoblasts and is downregulated under mechanical stimulation. It is not yet known how expression of sclerostin mediates the site-specific and temporal changes in mineralisation. To address this, we developed a 3D cellular niche of MC3T3 osteoblasts encapsulated within gelatin and applied mechanical loading to the constructs using a custom-designed compression bioreactor system (0.5% strain at 0.5 Hz, 1 hr/day) (VizStim) under continuous perfusion of cell culture media. Osteoblasts were pretreated with estrogen for 14 days, followed by estrogen withdrawal (EW) to simulate postmenopausal conditions. 3D constructs were successfully fabricated and actin staining revealed the formation of dendritic cells under both static and stimulated conditions indicative of osteocyte-like cells. Under static conditions, estrogen treatment enhanced production of calcium by osteoblasts when compared to the same cells cultured under estrogen deficient conditions. Overall, preliminary results propose a link between mechanical stimulation, estrogen deficiency and mineral production by osteoblasts. Ongoing studies are comparing the static and stimulated groups after a longer culture period of 21 days using sclerostin antibodies. This research aims to deliver further understanding of the mechanical regulation of bone formation, and will inform novel approaches for regeneration of bone tissue and treatment of osteoporosis.
