MSCs were pelleted into micromasses and differentiated in serum-free medium in the presence of TGF-β3 and dexamethasone. Immediately after centrifugation, the cells appeared as flattened pellets at the bottom of tubes. One day later, pellets had a thickened lip, and between days 2 and 3, pellet became spherical without any increase in size. Pellets then grew in size and pellet diameters increased to about 2-fold on days 7 and 14 (Fig. 3A) .