Mesenchymal stem cells show radioresistance in vivo.
Bottom Line: When irradiating human bone-derived MSC in vitro with increasing doses, the cells' self-renewal capabilities were greatly reduced.No significant differences between the untreated and 9 Gy irradiated bone with respect to proliferation and osteogenic differentiation were unveiled.Yet, cells isolated from 18 Gy irradiated specimens exhibited a reduced osteogenic differentiation capacity, and during the first 2 weeks proliferation rates were greatly diminished.
Affiliation: Institute for Biomedical Aging Research, Austrian Academy of Sciences, Innsbruck, Austria.Show MeSH
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Mentions: This observation prompted us to consider in vivo irradiated MSC as an indicator for vitality after treatment. Similar to the observations in vitro, MSC suffer damage, resulting in attenuation of cell intrinsic osteogenic differentiation capacity in vivo. To determine the impact of ionizing radiation on MSC that are borne within bone and bone marrow, mandible biopsies were taken from living animals directly after irradiation with a single dose of 9 or 18 Gy, the latter accounting for a BED of 60 Gy. Notably, long-term proliferation capacity of isolated MSC, which survived the radiation treatment, was comparable to those of non-irradiated counterparts (Fig. 5A). MSC, which had been isolated directly after the animals received a 9 Gy dose, exhibited no difference in colony forming capability, and also osteogenic potential was comparable to non-irradiated controls (Fig. 5B and C). These results suggested that a 9 Gy treatment is tolerated in as much pig mandible and surrounding tissue still contained viable cells, although at decreased numbers, which still exhibited long-term proliferation potential and osteogenic differentiation capacity. Moreover, the tissue showed no obvious signs of exuberant necrosis and only mild enduring inflammation became apparent. Yet, after irradiation with a single dose of 18 Gy MSC numbers were greatly reduced (Fig. 5B) and although isolated MSC still exhibited uninterrupted long-term proliferation potential (Fig. 5A), cellular properties were greatly affected as their osteogenic differentiation potential was attenuated (Fig. 5C). Conspicuously, MSC tolerate irradiation up to 9 Gy.
Affiliation: Institute for Biomedical Aging Research, Austrian Academy of Sciences, Innsbruck, Austria.