Microcarriers facilitate mineralization in MC3T3-E1 cells.

MC3T3-E1 cells showed mineral deposits after about 1 week of culture when incubated in the presence of microcarrier beads. These deposits appeared as white spots on the dish surface, and under light microscopy the cells showed multiple cell layers and mineralization around the microcarriers. The deposits stained positive with calcium-specific Von Kossa's method. Using conventional assay, alkaline phosphatase activity (ALP) and parathyroid hormone-stimulated intracellular cAMP production were lower in the microcarrier cultures than in the control, but using cytochemical methods, high alkaline phosphatase activity was found around the microcarriers. These results indicate that microcarriers facilitated the formation of multiple cell layers and provided a culture environment for mineralization.