by
John R. Fischer, Senior Reporter | January 02, 2018
Upon examining the progeny of cells eleven cellular generations following low-dose exposure, researchers found no differences between them and a control group of cells not treated with X-rays. The progeny of the cells also did not show any signs of genome instability, proliferation abnormalities or accelerated senescence.
The authors say their results challenge the linear no-threshold model, which estimates ionizing radiation to be harmful to all living cells regardless of the dosage, thereby providing insight for better treatment of patients.
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"Our findings provide evidence that the LNT model may not account for compensatory mechanisms inherently present in cells and may not predict the outcomes accurately. The truth is, when the LNT model was proposed, scientists not only did not know the double helix structure of the DNA molecule, they did not even know that DNA repair existed. Lastly, the radiation protection regulatory documents acknowledge that the LNT is a hypothesis; and like any hypothesis, it can be proved or disproved as new scientific knowledge accumulates, a detail that many forget."
"Our research suggests that the presence of γH2AX foci in cultured human stem cells 24 hours after low-dose X-ray irradiation is associated with cell division processes and does not lead to delayed effects related to aging,” Osipov said in a statement. “This is an important conclusion to draw, because γH2AX foci are now actively used in biodosimetry. Misunderstanding the biological significance of residual foci might lead to a severe overestimation of the risks associated with low-dose exposure."
Researchers caution against jumping to the conclusion that medical imaging does not increase health risks, explaining that stem cells are only a small fraction of cells within the body, and that the study did not directly measure transformation of irradiated cells into cancerous cells, meaning the results found only speak for the type of cells used, mesenchymal stem cells, which are indirectly related to cancerous transformation.
Research was financed partially through a grant from the Russian Foundation for Basic Research, and was conducted with the financial support of the Ministry of Education and Science of the Russian Federation.
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