Figure 6B. Effect of MSDK on osteoblast-mediated calcium mineralization. On day 21 of MSDK exposure, calcium deposition by differentiated, matured osteoblasts were evaluated via alizarin red staining on the (A) bottom chamber cells of transwell co-culture and (B) layered co-culture. Inset graph represents similar analysis in absence of Os+/MSDK. Each bar represents the mean concentration of alizarin red (μM) for respective groups normalized against Os-/Veh (n=3; Transwell co-culture: ****=p<.0001 vs. all groups, a=p<.01 vs. Os-/Veh, b=p<.05 vs. Os-/MSDK, c=p<.05 vs. Os+/Veh; Layered co-culture: ****=p<.0001 vs. all groups, a=p<.01 vs. Os-/Veh, b=p<.01 vs. Os-/MSDK, c=p<.01 vs. Os-/Veh). Os- =basal media, Os+ =osteogenic media, Veh= vehicle, Mel= melatonin, SC= strontium citrate, D3= vitamin D3 (Cholecalciferol), K2= vitamin K2 (MK7).