Defining the most potent osteoinductive culture conditions for MC3T3-E1 cells reveals no implication of oxidative stress or energy metabolism

MC3T3-E1 preosteoblastic cell line is widely utilised as a reliable in vitro system to assess bone formation. However, the experimental growth conditions for these cells hugely diverge and, particularly, the osteogenic medium (OSM) composition varies in research studies. Therefore, we aimed to define the ideal culture conditions for MC3T3-E1 subclone 4 cells with regards to mineralization capacity and explore if oxidative stress or cellular metabolism processes are implicated. Cells were treated with 9 different combinations of long-lasting ascorbate (Asc) and β-glycerophosphate (βGP) and osteogenesis/calcification were evaluated at 3 different time-points by qPCR, Western blotting and bone nodule staining. Key molecules of oxidative and metabolic pathways were also assessed. It was found that sufficient mineral deposition was achieved only in 150μg.mL -1 /2mM Asc/βGP combination at 21d in OSM and this was supported by Runx2, Alpl, Bglap and Col1a1 expression levels increase. NOX2 and SOD2 as well as PGC1α and Tfam were also monitored as indicators of redox and metabolic processes, respectively, where no differences were observed. Elevation in OCN protein levels and ALP activity showed that mineralisation comes as a result of these differences. This work defines the most appropriate culture conditions for MC3T3-E1 cells and could be used by other research laboratories in this field.