Growth Capacity of Human Cells after Exposure to Heavy Ions in a Phantom Head
- Paper number
IAC-12,A1,4,5,x13162
- Author
Dr. Christine Hellweg, Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR), Germany
- Coauthor
Dr. Thomas Berger, Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR), Germany
- Coauthor
Mr. Arif Ali Chishti, Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR), Germany
- Coauthor
Mrs. Christine Körner, Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR), Germany
- Coauthor
Dr. Chiara La Tessa, GSI Helmholtz Centre for Heavy Ion Research, Germany
- Coauthor
Mr. Sebastian Feles, Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR), Germany
- Coauthor
Mrs. Claudia Schmitz, Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR), Germany
- Coauthor
Dr. Patrick Lau, Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR), Germany
- Coauthor
Dr. Christa Baumstark-Khan, Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR), Germany
- Coauthor
Dr. Günther Reitz, Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR), Germany
- Year
2012
- Abstract
Radiation measurements using anthropomorphic phantoms provide more reliable data for space radiation exposure risk estimates. There are currently no published data available on depth distribution of biological effects of space relevant energetic heavy ion beams in a human phantom. Therefore, a bioassay using the red fluorescent protein tdTomato was established to complement the physical detector systems used in the head of a human phantom with intrinsically biologically weighted measures of cellular responses to simulated compounds of the radiation field in a space habitat. The plasmid ptdTomato-N1 in which tdTomato is controlled by a constitutively active strong viral promoter (CMV) was stably transfected into human embryonic kidney cells (HEK-ptdTomato-N1). Measurement of this reporter protein in a fluorescence microplate reader allowed rapid quantification of cell number and proliferation. X-ray doses above 4 Gy resulted in significant reduction of cellular proliferation as monitored by constitutive tdTomato expression. The growth curves of HEK-ptdTomato-N1 cells after Fe and Ni ion exposure revealed a strong dose-dependent reduction in cellular proliferation. HEK-ptdTomato-N1 cells were irradiated during growth in the phantom head with iron or nickel ions (1 GeV/nucleon, linear energy transfer - LET - 150 and 175 keV/µm) or with X-rays (200 kV). Therefore, the cells were seeded in strip well plates that were closed with lids during irradiation in the phantom head. Closing the culture vessels during irradiation did not affect the radiosensitivity of HEK-ptdTomato-N1 cells. The relative biological effectiveness (RBE) of iron and nickel ions in growth reduction with 200 kV X-rays as reference radiation is 17.5 and 5.8, respectively, based on the dose resulting in growth reduction to 37 \%. The relative growth of HEK-ptdTomato-N1 cells 100 h after exposure to nickel and iron ions in one slice of the Phantom head showed that survival of cells is highest in the back of the head and lowest in the forehead region, with the beam entering from the nose. Cellular responses to radiation as invading in the phantom head might contribute to the risk assessment of astronauts’ space radiation exposure. Acknowledgement: The experiments were performed in frame of the ESA-Iber program (AO-08-IBER-12) at the Helmholtz Center for Heavy Ion Research (GSI) in Darmstadt with support by Michael Scholz.
- Abstract document
- Manuscript document
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