Istituto Superiore di Sanità (ISS), Rome, Italy.
Istituto Nazionale di Fisica Nucleare (INFN) Sezione Roma 1, Rome, Italy.
Front Public Health. 2024 Oct 22;12:1404748. doi: 10.3389/fpubh.2024.1404748. eCollection 2024.
Radiobiological studies at low dose rates allow us to improve our knowledge of the mechanisms by which radiation exerts its effects on biological systems following chronic exposures. Moreover, these studies can complement available epidemiological data on the biological effects of low doses and dose rates of ionizing radiation. Very few studies have simultaneously compared the biological effects of low- and high-LET radiations at the same dose rate for chronic irradiation.
We compared, for the first time in the same experiment, the effects of chronic (dose rates as low as ~18 and 5 mGy/h) and acute irradiations on clonogenicity and micronucleus formation in AG1522 normal human skin fibroblasts in the confluent state exposed to doses of low- and high-LET radiation (gamma rays and alpha particles) to investigate any differences due to the different radiation quality and different dose rate (in the dose range 0.006-0.9 Gy for alpha particles and 0.4-2.3 Gy for gamma rays).
As expected, alpha particles were more effective than gamma rays at inducing cytogenetic damage and reduced clonogenic cell survival. For gamma rays, the cytogenetic damage and the reduction of clonogenic cell survival were greater when the dose was delivered acutely instead of chronically. Instead, for the alpha particles, at the same dose, we found equal cytogenetic damage and reduction of clonogenic cell survival for both chronic and acute exposure (except for the highest doses of 0.4 and 0.9 Gy, where cytogenetic damage is greater at a low dose rate).
The results of this study may have an impact on space and terrestrial radioprotection of humans at low doses and low dose rates, on biodosimetry, and on the use of ionizing radiation in medicine. These results also provide insights into understanding damage induction and cell reaction mechanisms following chronic exposure (at dose rates as low as 18 and 5 mGy/h) to low- and high-LET radiation.
低剂量率下的放射生物学研究使我们能够更好地了解辐射在慢性暴露后对生物系统产生影响的机制。此外，这些研究可以补充有关低剂量和剂量率电离辐射生物效应的现有流行病学数据。很少有研究同时在相同的剂量率下比较低和高 LET 辐射的生物效应。
我们首次在同一项实验中比较了低剂量率（低至约 18 和 5 mGy/h）和急性照射对汇合状态下 AG1522 正常人皮肤成纤维细胞克隆形成和微核形成的慢性照射的影响，以研究不同辐射质量和不同剂量率（对于α粒子在 0.006-0.9 Gy 范围内，对于γ射线在 0.4-2.3 Gy 范围内）下的任何差异。
正如预期的那样，α粒子比γ射线更有效地诱导细胞遗传损伤并降低克隆形成细胞的存活率。对于γ射线，当剂量以急性而不是慢性方式给予时，细胞遗传损伤和克隆形成细胞存活率的降低更大。相反，对于α粒子，在相同剂量下，我们发现慢性和急性暴露的细胞遗传损伤和克隆形成细胞存活率相等（除了 0.4 和 0.9 Gy 的最高剂量外，在低剂量率下细胞遗传损伤更大）。
这项研究的结果可能会对人类在低剂量和低剂量率下的空间和陆地辐射防护、生物剂量学以及电离辐射在医学中的应用产生影响。这些结果还深入了解了对低 LET 和高 LET 辐射的慢性暴露（低至 18 和 5 mGy/h 的剂量率）后损伤诱导和细胞反应机制。
