Non-physiological mineral deposition in vitro by primary human osteoblasts under osteogenic conditions

The pluripotency of human embryonic stem cells (hESCs) provides the unique opportunity to derive tissue specific cells, an ability of particular interest in regenerative medicine. In the study of bone regeneration, there is interest in directing hESCs to mesenchymal stem cells (MSCs), which under the appropriate conditions gives rise to mineral-producing osteoblasts. To evaluate the efficiency of such a process and cellular functionality, standard in vitro mineralization tests are employed to determine the cells´ ability to generate a mineralized matrix. To guide the cells in these tests from their progenitor state to functional osteoblasts, osteogenic supplements must be provided in culture. However, it is critical to discern between physiological (cell-mediated) and non-physiological mineralization in vitro. Here, we investigated the mineralization pattern of human osteoprogenitor cells in the presence of varying concentrations of the common osteogenic supplements fetal bovine serum, ß-glycerol phosphate, and dexamethasone.