Influence of Gold Nanoparticles on Radiation Dose Enhancement and Cellular Migration in Microbeam-Irradiated Cells

The focus of this research was the enhancement of radiation dose for microbeam radiotherapy (MRT) by the inclusion of gold nanoparticles (AuNPs) in the target. Microbeam radiotherapy is a technique that employs a very high dose rate of X-rays to kill highly resistant tumours such as glioma without jeopardizing the tolerance of normal tissue. The reduction of radiation dose rate used in this technique by using AuNPs may enhance the normal tissue tolerance while achieving better tumour control. In this study, microbeam kilovoltage X-ray of mean energy 125 keV from the SPring8 Synchrotron in Japan was used. The results show dose enhancement effects on endothelial cells by AuNPs which are consistent with previously documented results using broad beams of X-rays. It was also observed in this study that the inclusion of AuNPs accelerates cell migration towards the eradicated area which is important in normal tissue recovery. The phenomenon of cell migration is observed when cell fill depleted gaps that have been created by the microbeams or when such gaps are manually made by scratching the cell culture as a wound. The reason behind this acceleration of the rate of gap fillings is not well understood. However, it has been attributed to various biological processes and has also been thought of as being partially due to the effects of electrostatic charge of such particles. It could also be the combined effects of biological and electrostatic effects due to the charges of the particles inside the cells. Moreover, it is also observed that the cancerous glioma cell fills the gaps in much slower rates in comparison to the normal endothelial cells. This is consistent with the notion on which the MRT techniques are based.