Development of a method for assessing non-targeted radiation damage in an artificial 3D human skin model.

PURPOSE Despite the increasing concern about the effect of doses below 0.5 Gy and non-targeted exposures of ionising radiation on living organisms, the majority of radiobiological studies are conducted using in vitro cell lines. In order to be able to extrapolate the in vitro results to in vivo models with confidence, it would be of great benefit to develop a reproducible tissue system suitable for critical radiobiological assays. This manuscript describes the development of a reliable protocol to harvest cells from tissue samples and investigate the radiation damage induced on a single cell basis. MATERIALS AND METHODS To validate this approach as a potential tool for bystander experiments, the method focuses on analysing radiation damage in individual cells as a function of their relative position in the tissue. The experiments reported describe the micronucleus formation following partial irradiation with 3.5 MeV protons (0.1, 0.5 and 1 Gy) in an artificial human skin construct. RESULTS The reproducible and low background frequency of micronuclei measured in this system allows detection of small increases following radiation exposures. The effect was statistically significant at doses as low as 0.1 Gy in the directly irradiated as well as in the bystander cells. CONCLUSIONS The data presented provide evidence of a spatially dependent bystander effect whose magnitude decrease as a function of the distance from the directly exposed area.