Is it possible to mineralize PromoCell osteoblasts?

Yes; it is possible. Short protocol: Plate human osteoblasts in Osteoblast Mineralization Medium on  collagen I coated TC vessels. Incubate the cells for 17-21 days and change the medium every third day. Be careful not to disturb the cell monolayer. Fix the cells. The calcium deposition can be visualized by von Kossa or Alizarin Red staining. More detailed information on osteoblast mineralization and Alizarin Red S staining can be found in the attached Application Note.