Assessing skin exposure by measuring DNA damage in skin cells

在人体意外暴露于辐射之后，身体不同部位的剂量通常是高度不均匀的，并且皮肤区域可能比身体其他部位接收到显著更大的剂量。该项目的目标是开发可用于评估皮肤剂量的生物学方法，特别强调真皮和表皮细胞中的DNA损伤。我们以前的工作已经证明，它是可能的检测微核（MN）在皮肤成纤维细胞从大鼠和人采取数周后照射。因此，我们的假设是，在事故或恐怖分子煽动的事件造成的照射之后，可以使用小穿孔（3 mm）活检来估计皮肤剂量 可以在辐射暴露后数天或数周内服用。该项目将有四个具体目标。第一个目标建立在我们以前的研究基础上，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，使用尽可能小的活检，最初使用小鼠，然后使用人类皮肤。第二个具体目标将是研究预测皮肤所接受的剂量的可能性，使用直接在从皮肤活检获得的切片上进行的细胞核中蛋白质的辐射诱导病灶（RIF）的测量。同样，这项工作将在来自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遗传缺陷，例如SCID和ATM敲除）的皮肤中开始，并将在人类皮肤的研究中进行。 皮肤第三个具体目标是将这些技术扩展到检查高LET辐射（热中子）的照射。这些研究的重点将是利用这些技术获得与意外照射有关的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正在开发的技术相结合，这些技术在接受全身照射或部分全身照射的动物中进行，模拟人类在意外或恐怖分子引发的辐射暴露后的预期条件;我们将使用衍生终点来检查该项目中开发的缓解剂缓解皮肤损伤的能力。

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.