Yang H, Anzenberg V, Held K D
Department of Radiation Oncology, Massachusetts General Hospital/Harvard Medical School, Boston, MA 02114, USA.
Radiats Biol Radioecol. 2007 May-Jun;47(3):302-6.
At the low particle fluences of radiation to which astronauts are exposed in space, "non-targeted" effects such as the bystander response may have increased significance. The radiation-induced bystander effect is the occurrence of biological responses in unirradiated cells near to or sharing medium with cells traversed by radiation. The objectives of this study were to establish the responses of AG01522 diploid human fibroblasts after exposure to several heavy ions and energetic protons, as compared to X-rays, and to obtain initial information on the bystander effect in terms of cell clonogenic survival after Fe ion irradiation. Using a clonogenic survival assay, relative biological effectiveness (RBE) values at 10% survival were 2.5, 2.3, 1.0 and 1.2 for 1 GeV/amu Fe, 1 GeV/amu Ti, 290 MeV/amu C and 1 GeV/amu protons, respectively, compared to 250 kVp X-rays. For induction of micronuclei (MN), compared to the low LET protons, Fe and Ti are very effective inducers of damage, although C ions are similar to protons. Using a transwell insert system in which irradiated and unirradiated bystander cells share medium but are not touching each other, it was found that clonogenic survival in unirradiated bystander cells was decreased when irradiated cells were exposed to Fe ions or X-rays. The magnitude of the decrease in bystander survival was similar with both radiation types, reaching a plateau of about 80% survival at doses of about 0.5 Gy or larger.
在宇航员在太空中所遭受的低粒子注量辐射条件下，诸如旁观者效应等“非靶向”效应可能具有更大的意义。辐射诱导的旁观者效应是指在与受辐射穿过的细胞相邻或共享培养基的未受辐射细胞中发生生物反应。本研究的目的是确定AG01522二倍体人成纤维细胞在暴露于几种重离子和高能质子后与X射线相比的反应，并就铁离子辐照后细胞克隆存活方面获得关于旁观者效应的初步信息。使用克隆存活测定法，与250 kVp X射线相比，1 GeV/amu铁、1 GeV/amu钛、290 MeV/amu碳和1 GeV/amu质子在10%存活时的相对生物效能（RBE）值分别为2.5、2.3、1.0和1.2。对于微核（MN）的诱导，与低传能线密度质子相比，铁和钛是非常有效的损伤诱导剂，尽管碳离子与质子相似。使用一种Transwell插入系统，其中受辐照和未受辐照的旁观者细胞共享培养基但彼此不接触，结果发现当受辐照细胞暴露于铁离子或X射线时，未受辐照旁观者细胞中的克隆存活降低。两种辐射类型导致的旁观者存活降低幅度相似，在约0.5 Gy或更大剂量时达到约80%存活的平台期。
