Assessing skin exposure by measuring DNA damage in skin cells

人体意外暴露于辐射后，身体不同部位的剂量往往高度不同，皮肤区域受到的剂量可能比身体其他部位大得多。该项目的目标是开发可用于评估皮肤剂量的生物学方法，特别是真皮和表皮细胞中的DNA损伤。我们以前的工作已经证明，在照射后几周的大鼠和人的皮肤成纤维细胞中检测到微核(MN)是可能的。因此，我们的假设是，在由于事故或恐怖分子煽动的事件而暴露后，使用小冲孔(3毫米)活检来估计皮肤剂量是可能的。 这可能会在辐射暴露后的几天或几周内进行。该项目将有四个具体目标。第一个目标建立在我们之前的研究基础上，并将完善我们现有的技术，以建立最佳方法来测量从真皮成纤维细胞获得的MN，使用尽可能小的活组织检查，首先与小鼠合作，然后与人类皮肤合作。第二个具体目标将是通过直接在皮肤活检切片上测量细胞核中蛋白质的辐射诱导灶(RIF)来研究预测皮肤接受剂量的可能性。同样，这项工作将在各种不同品系的小鼠(野生型和具有影响辐射敏感性的已知基因缺陷，如SCID和ATM基因敲除)的皮肤中启动，并将在人类研究中进行后续研究 皮肤。第三个具体目标将扩展这些技术，以检查高LET辐射(热中子)的暴露情况。这些研究的重点将是利用这些技术获得与意外接触有关的RBE值的信息。最终的具体目标是将这些皮肤研究与该中心其他项目在接受全身照射或局部照射的动物身上开发的技术相结合，这些技术模拟了人类在意外或恐怖分子煽动的辐射暴露中暴露后的预期条件；我们将使用衍生的终点来检查该计划中开发的缓解剂对皮肤损伤的缓解能力。

Following accidental exposure of humans to irradiation, the dose to different parts of the body is often highly heterogeneous, and regions of the skin may receive substantially greater doses than other parts of the body. The goal of this project is to develop biological approaches that can be used to assess dose to the skin, with a particular emphasis on DNA damage in cells of the dermis and epidermis. Our previous work has demonstrated that it is possible to detect micronuclei (MN) in skin fibroblasts from both rats and humans taken weeks after irradiation. Thus, our hypothesis is that, following exposures due to accidents or terrorist-instigated incidents, it will be possible to estimate skin dose using a small punch (3 mm) biopsy that could be taken within a number of days or weeks after radiation exposure. The project will have four specific aims. The first aim builds on our previous studies and will refine our existing techniques to establish optimal methods to measure MN obtained from dermal fibroblasts using the smallest possible biopsy, working initially with mice and then with human skin. The second specific aim will be to investigate the potential for predicting the dose received by the skin, using measurements of radiation-induced foci (RIF) of proteins in the cell nuclei performed directly on sections obtained from skin biopsies. Again, the work will be initiated in skin from various different strains of mice (wild-type and with known genetic defects that influence radiosensitivity e.g. SCID and ATM knock-outs) and will be followed up in studies of human skin. The third specific aim will extend these techniques to examine exposure to high LET radiation (thermal neutrons). The focus of these studies will be to obtain information on RBE values relevant to accidental exposure using these techniques. The final specific aim will integrate these studies in skin with techniques being developed in other projects in the Center in animals given whole body irradiation or partial body irradiation, which simulate the conditions expected following exposure of humans in an accidental or terrorist-instigated radiation exposure; we will use the derived endpoints to examine the ability of mitigating agents developed in the program to mitigate against skin injury.