Concentration of bound calcium in human MCS cultures. Grey bars correspond to cultures cultivated in osteoinduction medium containing dexamethasone, ascorbate and β-glycerophosphate with uniaxial mechanical stimulation (2000 μstrain, 200 × day, 1 Hz). White bars correspond to control cultures without mechanical stimulation. The calcium concentration was measured at day 7, 14 and 21. Statistically significant differences between mechanically stimulated and mechanically unstimulated cultures are indicated by *.