Growth and maturation of human (MG63) osteoblasts in response to 16:0 OMPT and 1,25D.

A. MG63 osteoblasts were treated with 1,25D (100nM), 16:0 OMPT (micromolarμM) or a combination of these agents and left for three days under conventional cell culturing conditions prior to an assessment of cell growth. As anticipated for the pro-differentiating effects of 1,25D, there were fewer cells (*p<0.01 1,25D versus control) at the end of the culture period. In contrast the application of 16:0 OMPT led to a significant increase in cell numbers (**p<0.01 16:0 OMPT versus control). B. Alkaline phosphatase (ALP) is expressed in greater abundance as osteoblasts progress from an immature to a more differentiated phenotype. Enzyme activity is reliably monitored via the hydrolysis of p-nitrophenyl phosphate to p-nitrophenol (p-NP). The co-stimulation of MG63 cells with 100nM 1,25D and 16:0 OMPT yielded significant increases in total ALP activity by 72 h (*p < 0.001 versus agents in isolation). In each case the data shown are the mean + SD of 4 replicate samples and are a representative from three independent experiments.