Quantitation of osteoblast-like cell mineralization on tissue culture polystyrene and Ti-6Al-4V alloy disks by Tc-99m-MDP labeling and imaging in vitro

Technetium-99m-methylene-diphosphonate (Tc-99m-MDP) labeling was used to quantify mineralization of cultures of MC3T3 osteoblast-like cells in vitro. MC3T3 cells were cultured on tissue culture polystyrene (TCPS) in mineralizing and non-mineralizing media, and then labeled by Tc-99m-MDP. The gamma signal from labeled samples was imaged with a gamma camera and compared with the calcium content in the same samples determined by inductively coupled plasma. The high correlation (coefficient of determination, 0.88) between these two values validated the radiotracer uptake method as a quantitative analytical tool for certain mineralization studies in vitro. There was an association between mineralization and radionuclide uptake in the MC3T3 cultures on titanium alloy, but the attenuation of the gamma photons by the metal resulted in a less robust correlation. The results warrant implementation of this scintigraphic method for quantitative studies of osteoblast-mediated mineralization in vitro.