本研究在利用具有不同离子种类的重离子微束研究辐射质量依赖的旁观细胞效应。重离子微束是在国家量子科学技术研究院高崎离子加速器高级辐射应用中心产生的。碳离子（12C5+，220 MeV），氖离子（20Ne7+，260 MeV）和氩离子（40Ar13+，460 MeV）被用作微束，通过碳离子与缺乏缝隙连接抑制剂的细胞与缺乏抑制剂的细胞，碳离子与抑制剂的细胞相比，存活率（SF）在0.5和3小时照射后显著降低，但在24小时时，不论有无细胞杀伤，SFs相同。相反，在氩离子照射的细胞中，在0.5和3小时内没有观察到细胞杀伤效应，但在24小时内，不论有无抑制剂，SFs均显著降低，并且使用维生素C而不是二甲基亚砜，这种效应受到抑制。碳离子照射的细胞中的突变频率（MF）在0.5和3小时内是未照射对照组的8至6倍；然而，在使用缝隙连接抑制剂处理的细胞中未观察到突变。在24小时内，由各离子源引发的MF比例提高了3至5倍，并且在有无抑制剂的情况下相同。这些发现表明旁观细胞效应取决于生物学终点、离子种类和微束照射后的时间。© The Author(s) 2023. Published by Oxford University Press on behalf of The Japanese Radiation Research Society and Japanese Society for Radiation Oncology.

We investigated the radiation-quality-dependent bystander cellular effects using heavy-ion microbeams with different ion species. The heavy-ion microbeams were produced in Takasaki Ion Accelerators for Advanced Radiation Application, National Institutes for Quantum Science and Technology. Carbon (12C5+, 220 MeV), neon (20Ne7+, 260 MeV) and argon (40Ar13+, 460 MeV) ions were used as the microbeams, collimating the beam size with a diameter of 20 μm. After 0.5 and 3 h of irradiation, the surviving fractions (SFs) are significantly lower in cells irradiated with carbon ions without a gap-junction inhibitor than those irradiated with the inhibitor. However, the same SFs with no cell killing were found with and without the inhibitor at 24 h. Conversely, no cell-killing effect was observed in argon-ion-irradiated cells at 0.5 and 3 h; however, significantly low SFs were found at 24 h with and without the inhibitor, and the effect was suppressed using vitamin C and not dimethyl sulfoxide. The mutation frequency (MF) in cells irradiated with carbon ions was 8- to 6-fold higher than that in the unirradiated control at 0.5 and 3 h; however, no mutation was observed in cells treated with the gap-junction inhibitor. At 24 h, the MFs induced by each ion source were 3- to 5-fold higher and the same with and without the inhibitor. These findings suggest that the bystander cellular effects depend on the biological endpoints, ion species and time after microbeam irradiations with different pathways.© The Author(s) 2023. Published by Oxford University Press on behalf of The Japanese Radiation Research Society and Japanese Society for Radiation Oncology.