Current status of proton microbeam irradiation system at NIRS

Abstract

The development of SPICE (Single-Particle Irradiation system to Cell), a microbeam irradiation system, has been completed at the National Institute of Radiological Sciences (NIRS). The beam size has been improved to approximately 2 μm in diameter. Cell targeting system can irradiate up to 24,000 cells per hour and enables one to irradiation cells from a single proton. This facility is now in operation for collaborative researches.
From this year we started a study of effects on neural stem cells irradiated with a proton microbeam (SPICE). Neural stem cells are a subtype of progenitor cells in the developing fetal brain that can self-renew and generate both neurons and glia, which form a central nervous system. In the developing stage, radiation exposure is said one of causes of inducing microcephaly. Radiation effects with neural stem cells are yet to be understood. In order to clarify the mechanism that neural stem cells have radiation damages in the both processes of proliferation and differentiation, we used a microbeam. We prepared homogenous neural stem cells differentiated from ES cells by NSS (; Neural Stem Sphere) method, original differentiation-inducing method. Each of the targeted cells was irradiated. First of all, in the process of proliferation, we started studying about survival fraction, DNA damage and its repair of neural stem cells to a number of irradiated proton particles. In this announcement, we also report about current status of the development of SPICE.