Stem cells unharmed by low-dose x-rays

A team of researchers found stem cells remained healthy after exposure to low-dose x-ray radiation, according to a study published in Aging.

The authors, led by Andreyan N. Osipov with the Burnazyan Federal Medical Biophysical Center in Moscow, examined MSCs isolated from bone marrow aspirates taken from a 37-year-old male donor.

The study showed that yH2AX foci (indicators of damage to DNA) induced by an intermediate dose of X-ray exposure (100 mGy) returned to the control value within 24 hours, while low-dose irradiation (80 mGy) led to residual yH2AX foci still present after the same 24-hour period.

Authors also found, low-dose induced residual yH2AX foci were not co-localized with pATM foci and were observed predominately in the proliferating Ki67 positive (Ki67+) cells. The number of yH2AX foci and the fraction of non-proliferating (Ki67-) and senescent (SA-β-gal+) cells measured at passage 11 were increased in cultures exposed to an intermediate dose compared to unirradiated controls.

“Importantly, the dose of 80 mGy falls within the window of doses delivered to patients during medical diagnostic imaging procedures, such as CT scans that [are] often done in conjunction with stem cell therapy procedures,” wrote Osipov and colleagues. “Our results therefore provide important knowledge that can be utilized in regenerative medicine with respect to understanding health risks resulting from exposures of human stem cells to low doses of radiation.”