Ionizing Radiation Reduces Mineralization Without Inducing Cell Death: A Possible Silent Damage in Bone Formations

Bone mineralization is a highly regulated process dependent on osteoblast differentiation and the proper organization of the extracellular matrix. Ionizing radiation, frequently encountered in clinical therapies and space missions, can induce biological damage even at moderate doses, potentially impairing cellular function without necessarily causing cell death. This study investigated the effects of 2, 5, and 10 Gy of gamma radiation on the viability and mineralization capacity of MC3T3-E1 osteoblast-lineage cells over 7, 14, and 21 days. Cell viability was assessed via MTT assay, and mineralization was evaluated using Alizarin Red S and Von Kossa staining. Cell viability remained high across all conditions, indicating that radiation did not induce significant cytotoxicity. However, a clear, progressive, and dose-dependent reduction in mineralization was observed. Alizarin Red S quantification revealed decreases of approximately 26% (5 and 10 Gy) at day 7, 16% (5 Gy) and 35% (10 Gy) at day 14, and 47% (5 Gy) and 64% (10 Gy) at day 21, compared to non-irradiated controls. Von Kossa staining confirmed the reduction in phosphate deposition. These findings suggest that radiation selectively impairs osteogenic function despite preserved viability. This silent effect may compromise bone formation and warrants further investigation in clinical and spaceflight contexts.