Radiation-induced suppression of osteoblast differentiation in C2C12 cells

Abstract

Regenerative medicine offers hope of cure for many kinds of disease. One of major fields of regenerative medicine is the application of stem cells in bone reconstruction. Mouse derived myoblast cell line C2C12 was differentiated to osteogenic lineage by treatment with bone morphogenic protein 2 (BMP-2), and radiation-induced suppression was reported when cells were induced to osteogenic lineage 6 h after or before irradiation. On the other hand, heparin maintained BMP-2 level in the culture medium and prolonged its activity. Taking our body into considerations, such effects of extracellular matrix could not be left out. To evaluate the effects of ionizing radiation on osteoblast differentiation including the effects of extracellular matrix, we direct C2C12 cells into osteogenic lineage in the presence of heparin just after or 6 h irradiation. We find that ionizing radiation decreased alkaline phosphatase activity and the expression of collagen type I mRNA in BMP-2 treated cells. These findings suggest that X ray irradiation might be suppressing the differentiation of osteoblasts.