Effect of Stressed and Unstressed Cell Culture Environments on the Survival of MC3T3 Cells Cultured on Calcium Phosphates

The effect of Fetal Bovine Serum (FBS) deprivation on survival and apoptosis of osteoblasts cultured on various calcium phosphates was studied. Test materials were two calcium alkali orthophosphates (materials denominated: GB9 and GB14), which were compared to β-tricalcium phosphate (TCP). Tissue culture polystyrene (PS) served as control. Test materials were characterized by X-Ray Diffraction and scanning electron microscopy. An apoptotic challenge assay entailing serum withdrawal was applied: MC3T3-E1 osteoblasts were cultured for 72h on the test materials in serum containing medium, followed by incubation in serum free medium for another 24h. Serum withdrawal is an apoptotic challenge, which creates a stressed environment. Cells cultured on the test specimens in serum containing medium served as control. The TUNEL Assay was employed to quantify the percentage of apoptotic cells. GB9 and GB14 displayed a significantly lower percentage of apoptotic cells than TCP. TCP had significantly fewer apoptotic cells than PS. The percentage of apoptotic cells on GB9 and GB14 was less than 10%, while the number of apoptotic cells found on the untreated control specimens ranged between 5 and 7%. These findings indicate that GB9 and GB14 endow osteoblasts cultured on them with a decreased sensitivity to apoptosis, which corresponds well with the results of previous in vitro and in vivo studies.