Effects of ionizing radiation on human adipose derived mesenchymal stem cells and their differentiation towards the osteoblastic lineage

Abstract

Space travel presents many challenges to human health, including radiation exposure and musculoskeletal disuse. In addition, astronauts lose calcium from bones due to the uncoupling of bone formation and bone resorption. Bone forming osteoblasts are derived from undifferentiated MSCs. In this study, the ability of human adipose tissue derived stem cells (ATSC) to differentiate into the osteoblastic lineage was examined after radiation exposure as well as supplementation with osteogenic medium additives. After exposure to ionizing radiation changes in cellular morphology, cell cycle progression, as well as cellular radiosensitivity was characterized. Exposure to ionizing radiation resulted in an accumulation of cells in the G2/M phase of the cell cycle, concerning both cell lines. Alizarin Red S staining as well as quantitative determination of bone cell differentiation was performed by analyzing the hydroxyapatite content of the ECM. The results demonstrated LW24 deposited less calcium compared to SAOS-2. Additionally, gene expression analysis during differentiation process revealed expression of genes that are required for skeletal development, bone mineral metabolism and transcription factors. Detailed investigation of stem cell differentiation after radiation exposure is required to assure health of astronauts in upcoming space missions.