Buonanno M, Randers-Pehrson G, Smilenov L B, Kleiman N J, Young E, Ponnayia B, Brenner D J
a Radiological Research Accelerator Facility, Columbia University, Irvington, New York 10533;
b Center for Radiological Research and.
Radiat Res. 2015 Aug;184(2):219-25. doi: 10.1667/rr14057.1. Epub 2015 Jul 24.
Radiation-induced bystander effects have been observed in vitro and in cell and tissue culture models, however, there are few reported studies showing these effects in vivo. To our knowledge, this is the first reported study on bystander effects induced by microbeam irradiation in an intact living mammal. The mouse ear was used to investigate radiation-induced bystander effects in keratinocytes, utilizing a 3 MeV proton microbeam (LET 13.1 keV/μm) with a range in skin of about 135 μm. Using a custom-designed holder, the ear of an anesthetized C57BL/6J mouse was flattened by gentle suction and placed over the microbeam port to irradiate cells along a 35 μm wide, 6 mm long path. Immunohistochemical analysis of γ-H2AX foci formation in tissue sections revealed, compared to control tissue, proton-induced γ-H2AX foci formation in one of the two epidermal layers of the mouse ear. Strikingly, a higher number of cells than expected showed foci from direct irradiation effects. Although the proton-irradiated line was ~35 μm wide, the average width spanned by γ-H2AX-positive cells exceeded 150 μm. Cells adjacent to or in the epidermal layer opposite the γ-H2AX-positive region did not exhibit foci. These findings validate this mammalian model as a viable system for investigating radiation-induced bystander effects in an intact living organism.
辐射诱导的旁观者效应已在体外以及细胞和组织培养模型中被观察到，然而，鲜有报道显示这些效应在体内的情况。据我们所知，这是首次报道关于在完整活体哺乳动物中微束辐照诱导旁观者效应的研究。使用3兆电子伏特质子微束（线性能量传递为13.1千电子伏特/微米），其在皮肤中的射程约为135微米，利用小鼠耳朵来研究角质形成细胞中的辐射诱导旁观者效应。使用定制设计的固定器，将麻醉后的C57BL/6J小鼠的耳朵通过轻柔抽吸使其变平，并放置在微束端口上方，以沿着一条35微米宽、6毫米长的路径照射细胞。组织切片中γ-H2AX焦点形成的免疫组织化学分析显示，与对照组织相比，质子诱导的γ-H2AX焦点在小鼠耳朵的两层表皮之一中形成。引人注目的是，显示出直接辐照效应焦点的细胞数量比预期的要多。尽管质子辐照线宽约为35微米，但γ-H2AX阳性细胞跨越的平均宽度超过150微米。与γ-H2AX阳性区域相邻或在其对面表皮层中的细胞未显示出焦点。这些发现证实了这个哺乳动物模型是一个用于在完整活生物体中研究辐射诱导旁观者效应的可行系统。
