Green-Synthesized Magnesium Hydroxide Nanoparticles Induced Osteoblastic Differentiation in Bone Co-Cultured Cells

In this work, magnesium hydroxide NPs were synthesized using water (Mg(OH)₂ NPs) or a rose hip (RH) extract (Mg(OH)₂RH NPs) and tested for the bone cells' effects in co-cultured osteoblastic and osteoclastic cells, using a Transwell^® insert system, allowing reciprocal cell paracrine interactions. Behavior of each cell population was characterized for typical phenotype markers, at days 1 and 6. Cell cultures treated with osteogenic/osteoclastogenic inducers were used as positive control of cell differentiation. The NPs presented a round shape morphology with an average diameter ~90 nm (Mg(OH)₂ NPs) and below 10 nm (Mg(OH)₂RH NPs. Both NPs induced osteoblastic and osteoclastic behavior similarly to that observed in induced osteoblastic and osteoclastic cultures (positive controls). Differences between the two types of particles were evident at the gene expression level. Compared to Mg(OH)₂ NPs, the green-synthesized NPs greatly increased the expression of osteoblastic genes coding for the early markers ALP and collagen type 1 and the later transcription factor osterix, while decreasing the expression of osteoclastogenic genes, namely the essential transcription factor NFATC1, TRAP and the genes coding for the functional markers CA2 and CTSK. Overall, a positive added effect could be hypothesized for Mg(OH)₂RH NPs with potential usefulness to promote bone formation in regenerative applications.