Quantitative analysis of cell-mediated calcium accretion normalized to cellular protein content after 14 days of hMSC culture in the complete growth medium (CGM) or the osteogenic medium (ODM). hMSC isolated from osteoporotic donors (A, B, C) exhibited a significantly (*p<0.05, **p<0.01) higher calcium/protein ratio than hMSC isolated from young, nonosteoporotic donors (D, E).