Cytogenetic Effects of Ionizing Radiation in Peripheral Lymphocytes of ISS Crewmembers (Chromosome-2) - 10.21.14
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Chromosome-2, a European Space Agency experiment, is a continuation of the Chromosome investigation performed on earlier ISS expeditions. White blood cells (lymphocytes) are collected from crewmembers preflight and postflight. The lymphocytes are examined using different analytic methods to determine quantity and quality of genetic changes resulting from exposure to cosmic radiation, particularly ionizing radiation.
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The Chromosome-2 study determined that current astronaut radiation exposure fall well below the NASA limit, with galactic cosmic rays responsible for 80 percent or more of dose absorbed aboard the station. Early studies indicate that radiation during long-duration flights can increase chromosome damage, whereas shorter missions do not. Samples collected within a week or two of space flight provide reliable estimates of radiation dose and risk, but retrospective doses may be difficult to estimate because chromosomal damages disappear over time. Estimates from individuals on repeated or very long missions also may be complicated by an adaptive response to space radiation.
European Space Agency (ESA), Noordwijk, , Netherlands
Sponsoring Space Agency
European Space Agency (ESA)
ISS Expedition Duration
October 2005 - April 2008
Previous ISS Missions
Earlier versions of this experiment flew on the Space Shuttle and the Russian Space Station, Mir, as well as, ISS Expeditions 6-11.
- This study will assess changes in the morphology of chromosomes, particularly chromosomal aberrations by taking into account the sensitivity to radiation by each crew member. The frequency and the type of chromosomal aberrations depend on characteristics and doses of ionizing radiation the crewmembers are exposed to while in orbit.
- Chromosomes collected from blood lymphocytes are scored for different types of abnormalities before and after a stay on ISS. Some of the analysis methods are new, and will provide a new way of visualizing all changes, particularly those increasing the risk of cancer.
Cosmic radiation is a major risk factor in manned space missions. This investigation will give a better insight into the mutagenic burden of astronauts during space flights as consequence of exposure to the complex cosmic radiation field. Although it can be assumed that radiation plays a major role in mutation induction in astronauts, synergistic influences such as weightlessness, acceleration, vibration hyperthermia, noise microwave radiation, physical exercises, trauma, and infections cannot be ruled out.
During flights astronauts are chronically exposed to radiations of solar and galactic origin. The space radiation field consists of electrons, protons, heavy particles, and secondary radiation like bremsstrahlung, neutrons, and charged particles created by interactions of primary radiations with nuclei of spacecraft shielding material or the human body (Reitz et al., 1996). The contribution of the dose of single radiation types depends on altitude and inclination of the spacecraft, effective shielding thickness and solar activity during the mission.
The Chromosome-2 experiment will use astronauts as test subjects, but no actual in-flight experiment or data collection will be carried out. To assess the genetic impact of space radiation, blood (15 mL) is drawn before and directly after flights by venous puncture. Whole blood cultures will be set up with phytohemagglutinin to stimulate lymphocytes to undergo mitoses. After 48 h mitotic cells will be arrested with Colcemid, fixed and prepared on slides for microscopic analysis. The preparations will be scored for chromosomal aberrations. Three different staining procedures shall be performed to assess all types of aberrations induced by ionising radiations:
- classical Giemsa block-staining to score dicentric and ring chromosomes
- multicolor fluorescence in-situ hybridisation to score reciprocal translocations and insertions
- multicolor banding fluorescence in-situ hybridisation of a selected chromosome pair to score for inversions and translocations between homologous chromosomes.
The association of chromosomal aberrations with an enhanced cancer risk stresses the importance of the planned research. The data obtained will be helpful in order to carefully plan space flight missions.
As astronauts spend longer periods in space, it has become more important to accurately measure radiation doses and assess individual risk for long-duration space flights. Chromosome damage in peripheral blood lymphocytes, a type of white blood cell (WBC), is commonly used as an indicator of radiation exposure, and the introduction of the fluorescence in situ hybridization (FISH) chromosome painting technique has made it possible to "paint" individual chromosomes with different colors so alterations can be identified as multi-color chromosomes allowing for more detailed and accurate analysis.
NASA has implemented a radiation biodosimetry program that utilizes FISH to determine chromosomal damage in US astronauts who participate in long-duration missions. All crewmembers returning from ISS missions are evaluated for chromosomal damage in lymphocyte cells with this technique. For this study, physical and biological doses for 23 ISS astronauts yielded average effective doses and individual or population-based biological doses for the approximately 6-month missions of 85 or 81 mGy-Eq (milligray-equivalent), respectively, which is well below NASA limit of 250 mGy-Eq per 30 days. For comparison, the average radiation dose from a chest X-ray is < 0.25 mGy. Analyses showed that galactic cosmic rays (GCR) is the major source, responsible for 80% or more, of radiation organ dose absorbed on the ISS. Comparisons of models to clinical data showed that space radiation effective doses can now be predicted to within about a +15% accuracy (George et al., 2011, Cucinotta et al., 2008).
Early chromosome studies strongly indicated that the radiation dose absorbed during a long-duration flight can cause quantifiable increases in chromosome damage, whereas shorter missions of a few weeks or less did not show measurable effects. These previous studies focused on the detection of dicentric chromosomes (2 partial chromosomes joined at broken ends resulting in a chromosomal structure having 2 distinct pinched areas called centromeres) which are known to decay over time with an average half-life of about 3 years, but more recent studies indicate that this rate of decay could vary greatly between individuals (Durante, 2005). In addition, follow-up measurements of chromosome damage in the blood lymphocytes by FISH from 5 months to more than 5 years after space flight revealed a time-dependent loss of "stable’" aberrations as well in blood lymphocytes, with half-lives ranging from 10 to 58 months. Current available data show that biodosimetry analyses on samples collected within a week or two of return from space provides a reliable estimate of equivalent radiation dose and risk after exposure to space radiation of a few months or more. However, retrospective doses may be more difficult to estimate because of the fairly rapid time-dependent loss of "stable" chromosomal aberrations in blood lymphocytes. Also, biodosimetry estimates from individuals who participate in repeated missions, or very long (interplanetary) missions, may be complicated by an adaptive response to space radiation and/or changes in lymphocyte survival and repopulation (George et al., 2005, 2007).
Radiation exposure for missions beyond low earth orbit will be much greater because of the absence of the magnetic protection provided by the Earth. Understanding the biological effects of such exposures and developing effective countermeasures is a major endeavor and is the focus of current international research efforts (Cucinotta, 2011).
George KA, Chappell LJ, Cucinotta FA, Cucinotta FA. Persistence of space radiation induced cytogenetic damage in the blood lymphocytes of astronauts. Mutation Research - Genetic Toxicology and Environmental Mutagenesis. 2010 August; 701(1): 75-79.
George KA, Willingham V, Cucinotta FA, Cucinotta FA. Stability of Chromosome Aberrations in the Blood Lymphocytes of Astronauts Measured After Space Flight by FISH Chromosome Painting. Radiation Research. 2005; 164(4): 474-480. DOI: 10.1667/RR3323.1.
Cucinotta FA, Cucinotta FA, Kim MY, Willingham V, George KA. Physical and Biological Organ Dosimetry Analysis for International Space Station Astronauts. Radiation Research. 2008 July; 170(1): 127-138. DOI: 10.1667/RR1330.1.
George KA, Rhone J, Beitman A, Cucinotta FA, Cucinotta FA. Cytogenetic damage in the blood lymphocytes of astronauts: Effects of repeat long-duration space missions. Mutation Research - Genetic Toxicology and Environmental Mutagenesis. 2013 August 30; 756(1-2): 165-169. DOI: 10.1016/j.mrgentox.2013.04.007. PMID: 23639573.
Durante M. Biomarkers of Space Radiation Risk. Radiation Research. 2005; 164(4 Pt 2): 467-473. PMID: 16187751.
George KA, Durante M, Cucinotta FA, Cucinotta FA. Chromosome Aberrations in Astronauts. Advances in Space Research. 2007; 40(4): 483-490. DOI: 10.1016/j.asr.2007.03.100.
Cucinotta FA, Cucinotta FA. Space Radiation Organ Doses for Astronauts on Past and Future Missions. NASA Technical Publication; 2006.
Ground Based Results Publications
Johannes C, Horstmann M, Durante M, Chudoba I, Obe G. Chromosome intrachanges and interchanges detected by multicolor banding in lymphocytes: searching for clastogen signatures in the human genome. Radiation Research. 2004; 161: 540-548.
Fedorenko BS, Druzhinin S, Yudaeva L, Petrov VP, Akatov YA, Snigiryova GP, Novitskaya NN, Shevchenko V, Rubanovich A. Cytogenetic studies of blood lymphocytes from cosmonauts after long-term space flights on Mir station. Advances in Space Research. 2001; 27(2): 355-359. PMID: 11642297.
Hada M, Gersey B, Saganti PB, Wilkins R, Cucinotta FA, Cucinotta FA, Wu H. mBAND analysis of chromosome aberrations in human epithelial cells induced by γ-rays and secondary neutrons of low dose rate. Mutation Research - Genetic Toxicology and Environmental Mutagenesis. 2010 August; 701(1): 67-74. DOI: 10.1016/j.mrgentox.2010.03.009. PMID: 20338263.
Obe G, Johannes I, Johannes C, Hallman K, Reitz G, Facius R. Chromosomal aberrations in blood lymphocytes of astronauts after long-term space flights. International Journal of Radiation Biology. 1997; 72(6): 727-734.
George KA, Durante M, Wu H, Willingham V, Badhwar GD, Cucinotta FA, Cucinotta FA. Chromosome aberrations in the blood lymphocytes of astronauts after space flight. Radiation Research. 2001 December; 156(6): 731-738. PMID: 11741497.
Chatterjee A, Borak TH. Physical and biological studies with protons and HZE particles in a NASA supported research center in radiation health. Physica Medica: European Journal of Medical Physics. 2001; 17(Suppl 1): 59-66.
George KA, Wu H, Willingham V, Cucinotta FA, Cucinotta FA. The effect of space radiation on the induction of chromosome damage. Physica Medica: European Journal of Medical Physics. 2001; 17(Suppl 1): 222-225. PMID: 11776981.
Horstmann M, Durante M, Johannes C, Obe G. Chromosomal intrachanges induced by swift iron ions. Advances in Space Research. 2005; 35(2): 276-279. DOI: 10.1016/j.asr.2004.12.031.
Wu H, George KA, Willingham V, Cucinotta FA, Cucinotta FA. Comparison of chromosome aberration frequencies in pre- and post-flight astronaut lymphocytes irradiated in vitro with gamma rays. Physica Medica: European Journal of Medical Physics. 2001; 17(Suppl 1): 229-231. PMID: 11776983. [Also Biodosimetry related.]
Obe G, Facius R, Reitz G, Johannes I, Johannes C. Manned missions to Mars and chromosome damage. International Journal of Radiation Biology. 1999; 75(4): 429-433. PMID: 10331847.
Goedecke W, Obe G, Bergau L. Cytogenetic investigations in flight personnel. Radiation Protection Dosimetry. 1999; 86(4): 275-278. PMID: 11543396.
Durante M, Bonassi S, George KA, Cucinotta FA, Cucinotta FA. Risk estimation based on chromosomal aberrations induced by radiation. Radiation Research. 2001 November; 156(5 pt 2): 662-667. PMID: 11604089.
ESA Erasmus Experiment Archive.
Columbus Mission - European Experiment Programme
University of Duisburg Essen
Researchers use mFISH to study human chromosomal pairs. This photo shows that there has been a reciprocal exchange (translocation between chromosomes 11 and 12 and between 13 and 22) in blood lymphocytes of a crew member after space flight.
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Classical Giemsa staining makes it possible to detect major structural changes. (a) shows normal undamaged chromosomes, (b) shows a dicentric chromosome and an associated acentric fragment indicated by arrows.
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The mBAND method is used to detect aberrations within chromosomes as shown in the photo. An interstitial piece is lost from one of the two chromosomes 5. Image courtesy of University of Duisburg - Essen.
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