Effects of Ionizing Radiation on Osteogenic Differentiation of Human Adipose-Derived Multipotent Mesenchymal Stromal Cells

Abstract

During space flight, astronauts are way more exposed to cosmic and solar radiation in comparison to earth conditions. Specifically with respect to interplanetary travel, the protection of the earth’s magnetic field would be almost lost completely and the hulls of spacecraft would not prevent significant amounts of incoming radiation from penetrating. As astronauts lose bone mass and strength during their mission due to microgravity and the resulting lack of exercise, it is especially important for the bones to be able to regenerate these losses. In this study it was evaluated if increased radiation has an influence on osteoblast commitment capabilities of bone maintaining stem cells. To do so, human multipotent mesenchymal stromal cells were isolated out of lipoaspirate, induced towards the osteogenic lineage and exposed to X-rays of 2 Gy and 4 Gy. It was found that X-rays at this dose do not act as an unspecific trigger for osteogenic differentiation. A quantitative analysis of calcium depositions during osteogenesis showed that early disturbance of the differentiation process by X-rays caused a delay or even an impairment of osteoblast commitment in vitro. On the other hand, no significant differences in osteoblast commitment during four weeks of differentiation were found when the cells were exposed after week two of induction. This suggests an effect of ionizing radiation only in early osteogenesis.