A Fluorometric Method for the Quantification of Cell Number in Complex Differentiating Osteoblast-Osteocyte Cultures

Osteoblast/osteocyte cultures continue to emerge as essential tools for bone biology research in vitro. The change in cell number is an important parameter to be considered for investigating osteogenic differentiation. However, there is no reliable method for quantifying absolute cell count in differentiating osteoblast/osteocyte cultures because of their strongly adherent, multi-layered, super-confluent nature, and their accumulated extracellular matrix production which progressively mineralises in vitro. We developed a practical, simple and cost-effective method based on the fluorometric quantification of a nucleic dye, GelRed™, to enumerate cell number in osteoblast/osteocyte cultures. This method may also be suitable for quantifying cell numbers on other mammalian adherent cell types.