Bioactive glass ions as strong enhancers of osteogenic differentiation in human adipose stem cells

Bioactive glasses are known for their ability to induce osteogenic differentiation of stem cells. To elucidate the mechanism of the osteoinductivity in more detail, we studied whether ionic exts. prepd. from a com. glass S53P4 and from three exptl. glasses (2-06, 1-06 and 3-06) are alone sufficient to induce osteogenic differentiation of human adipose stem cells. Cells were cultured using basic medium or osteogenic medium as ext. basis. Our results indicate that cells stay viable in all the glass exts. for the whole culturing period, 14 days. At 14 days the mineralization in osteogenic medium exts. was excessive compared to the control. Parallel to the increased mineralization we obsd. a decrease in the cell amt. Raman and Laser Induced Breakdown Spectroscopy analyses confirmed that the mineral consisted of calcium phosphates. Consistently, the osteogenic medium exts. also increased osteocalcin prodn. and collagen Type-I accumulation in the extracellular matrix at 13 days. Of the four osteogenic medium exts., 2-06 and 3-06 induced the best responses of osteogenesis. However, regardless of the enhanced mineral formation, alk. phosphatase activity was not promoted by the exts. The osteogenic medium exts. could potentially provide a fast and effective way to differentiate human adipose stem cells in vitro.