Quantitative monitoring of in vitro mineralization process using fluorescent dyes

Human osteoblastic cell line, HOS 58 cells, were cultured in a medium containing fluorescent dyes of calcein or xylenol orange. The dyes have high affinity to calcium, therefore, were deposited into mineralized extracellular matrices of HOS 58 cells. There was a linear correlation between mineralizetion volume and the depositon of dyes. In contrast with these findings, only basal level of the deposition was detected in fibroblast culture. These data indicate that in vitro mineralization by HOS 58 cells can be quantified and monitored in situ during the continuous culture periods.