Biological Effects Of Space Radiation Research Articles

WormSpace μ-TAS enabling automated on-chip multi-strain culturing and multi-function imaging of Caenorhabditis elegans at the single-worm level on the China Space Station.

As a model organism for space biology experiments, Caenorhabditis elegans (C. elegans) has low demand for life support and strong resistance to unfavorable environments, making experimentation with C. elegans relatively easy and cost-effective. Previously, C. elegans has been flown in several spaceflight investigations, but there is still an urgent need for analytical platforms enabling on-orbit automated monitoring of multiple phenotypes of worms, such as growth and development, movement, changes of biomarkers, etc. To solve this problem, we presented a fully integrated microfluidic system (WormSpace μ-TAS) with an arrayed microfluidic chip (WormChip-4.8.1) and a replaceable microfluidic module (WormChip cartridge), which was compatible with the experimental facility on the China Space Station (CSS). By adopting technologies of programmed fluid control based on liquid medium CeMM as well as multi-function imaging with a camera mounted on a three-dimensional (3D) transportation stage, automated and long-term experimentation can be performed for on-chip multi-strain culturing and bright-field and fluorescence imaging of C. elegans at the single-worm level. The presented WormSpace μ-TAS enabled its successful application on the CSS, achieving flight launch of the sample unit (WormChip cartridge) at low temperature (controlled by a passive thermal case at 12 °C), automated 30-day cultivation of 4 strains of C. elegans, on-orbit monitoring of multiple phenotypes (growth and development, movement, and changes of fluorescent protein expression) at the single worm-level, on-chip fixation of animals at the end of the experiment and returning the fixed samples to earth. In summary, this study presented a verified microfluidic system and experimental protocols for automated on-chip multi-strain culturing and multi-function imaging of C. elegans at the single-worm level on the CSS. The WormSpace μ-TAS will provide a novel experimental platform for the study of biological effects of space radiation and microgravity, and for the development of protective drugs.

Simulated galactic cosmic ray exposure activates dose-dependent DNA repair response and down regulates glucosinolate pathways in arabidopsis seedlings.

Outside the protection of Earth's magnetic field, organisms are constantly exposed to space radiation consisting of energetic protons and other heavier charged particles. With the goal of crewed Mars exploration, the production of fresh food during long duration space missions is critical for meeting astronauts' nutritional and psychological needs. However, the biological effects of space radiation on plants have not been sufficiently investigated and characterized. To that end, 10-day-old Arabidopsis seedlings were exposed to simulated Galactic Cosmic Rays (GCR) and assessed for transcriptomic changes. The simulated GCR irradiation was carried out in the NASA Space Radiation Laboratory (NSRL) at Brookhaven National Lab (BNL). The exposures were conducted acutely for two dose points at 40 cGy or 80 cGy, with sequential delivery of proton, helium, oxygen, silicon, and iron ions. Control and irradiated seedlings were then harvested and preserved in RNAlater at 3 hrs post irradiation. Total RNA was isolated for transcriptomic analyses using RNAseq. The data revealed that the transcriptomic responses were dose-dependent, with significant upregulation of DNA repair pathways and downregulation of glucosinolate biosynthetic pathways. Glucosinolates are important for plant pathogen defense and for the taste of a plant, which are both relevant to growing plants for spaceflight. These findings fill in knowledge gaps of how plants respond to radiation in beyond-Earth environments.

Comparison of biological measurement and physical estimates of space radiation in the International Space Station

Nowadays, ordinary people can travel in space, and the possibility of extended durations in an environment such as moon of the Earth and Mars with higher space radiation exposures compared to past missions, is increasing. Until now, the physical doses of space radiation have been measured, but measurement of direct biological effects has been hampered by its low dose and low dose-rate effect. To assess the biological effects of space radiation, we launched and kept frozen mouse embryonic stem (ES) cells in minus eighty degree Celsius freezer in ISS (MELFI) on the International Space Station (ISS) for a maximum of 1,584 days. The passive dosimeter for life science experiments in space (PADLES) was attached on the surface of the sample case of the ES cells. The physical dosimeter measured the absorbed dose in water. After return, the frozen cells were thawed and cultured and their chromosome aberrations were analyzed. Comparative experiments with proton and iron ion irradiation were performed at particle accelerators on Earth. The wild-type ES cells showed no differences in chromosomal aberrations between the ground control and ISS exposures. However, we detected an increase of chromosome aberrations in radio-sensitized histone H2AX heterozygous-deficient mouse ES cells and found that the rate of increase against the absorbed dose was 1.54-fold of proton irradiation at an accelerator. On the other hand, we estimated the quality factor of space radiation as 1.48 ± 0.2. using formulas of International Commission of Radiation Protection (ICRP) 60. The relative biological effectiveness (RBE) observed from our experiments (1.54-fold of proton) was almost equal (1.04-fold) to the physical estimation (1.48 ± 0.2). It should be important to clarify the relation between biological effect and physical estimates of space radiation. This comparative study paves a way to reveal the complex radiation environments to reduce the uncertainty for risk assessment of human stay in space.

Space Radiation Protection Countermeasures in Microgravity and Planetary Exploration.

Background: Space radiation is one of the principal environmental factors limiting the human tolerance for space travel, and therefore a primary risk in need of mitigation strategies to enable crewed exploration of the solar system. Methods: We summarize the current state of knowledge regarding potential means to reduce the biological effects of space radiation. New countermeasure strategies for exploration-class missions are proposed, based on recent advances in nutrition, pharmacologic, and immune science. Results: Radiation protection can be categorized into (1) exposure-limiting: shielding and mission duration; (2) countermeasures: radioprotectors, radiomodulators, radiomitigators, and immune-modulation, and; (3) treatment and supportive care for the effects of radiation. Vehicle and mission design can augment the overall exposure. Testing in terrestrial laboratories and earth-based exposure facilities, as well as on the International Space Station (ISS), has demonstrated that dietary and pharmacologic countermeasures can be safe and effective. Immune system modulators are less robustly tested but show promise. Therapies for radiation prodromal syndrome may include pharmacologic agents; and autologous marrow for acute radiation syndrome (ARS). Conclusions: Current radiation protection technology is not yet optimized, but nevertheless offers substantial protection to crews based on Lunar or Mars design reference missions. With additional research and human testing, the space radiation risk can be further mitigated to allow for long-duration exploration of the solar system.

Repair Kinetics of DNA Double Strand Breaks Induced by Simulated Space Radiation.

Radiation is unavoidable in space. Energetic particles in space radiation are reported to induce cluster DNA damage that is difficult to repair. In this study, normal human fibroblasts were irradiated with components of space radiation such as proton, helium, or carbon ion beams. Immunostaining for γ-H2AX and 53BP1 was performed over time to evaluate the kinetics of DNA damage repair. Our data clearly show that the repair kinetics of DNA double strand breaks (DSBs) induced by carbon ion irradiation, which has a high linear energy transfer (LET), are significantly slower than those of proton and helium ion irradiation. Mixed irradiation with carbon ions, followed by helium ions, did not have an additive effect on the DSB repair kinetics. Interestingly, the mean γ-H2AX focus size was shown to increase with LET, suggesting that the delay in repair kinetics was due to damage that is more complex. Further, the 53BP1 focus size also increased in an LET-dependent manner. Repair of DSBs, characterized by large 53BP1 foci, was a slow process within the biphasic kinetics of DSB repair, suggesting non-homologous end joining with error-prone end resection. Our data suggest that the biological effects of space radiation may be significantly influenced by the dose as well as the type of radiation exposure.

Determination of Chromosome Aberrations in Human Fibroblasts Irradiated by Mixed Fields Generated with Shielding.

To better study biological effects of space radiation using ground-based facilities, the NASA Space Radiation Laboratory (NSRL) at the Brookhaven National Laboratory has been upgraded to rapidly switch ions and energies. This has allowed investigators to design irradiation protocols comprising a mixture of ions and energies more indicative of the galactic cosmic ray (GCR) environment. Despite these advancements, beam selection and delivery schemes should be optimized against facility and experimental constraints and validated to ensure such irradiations are a suitable representation of the space environment. Importantly, since experiments are time consuming and expensive, models capable of predicting biological outcomes over a range of irradiation conditions (single ion, sequential multi ion or mixed fields) are needed to support such efforts. In this work, human fibroblasts were placed behind 20 g/cm2 aluminum and 10.345 g/cm2 polyethylene and irradiated separately by 344 MeV hydrogen, 344 MeV/n helium, 450 MeV/n oxygen and 950 MeV/n iron ions at various doses. The fluorescence in situ hybridization (FISH) whole chromosome painting technique was then used to assess the cells for chromosome aberrations (CAs), notably simple exchanges. A multi-scale modeling approach was also developed to predict the formation of chromosome aberrations in these experiments. The Geant4 simulation toolkit was used to determine the spectra of particles and energies produced by interactions between the incident beams and shielding. The simulated mixed field generated by shielding was then transferred into the track structure code, RITRACKS (relativistic ion tracks), to generate three-dimensional (3D) voxelized dose maps at the nanometer scale. Finally, these voxel dose maps were input into the new damage and repair model, RITCARD (radiation-induced tracks, chromosome aberrations, repair and damage), to predict the formation of various CAs. The multi-scale model described herein is a significant advancement for the computational tools used to predict biological outcomes in cells exposed to highly complex, mixed ion fields related to the GCR environment. Results show that the simulation and experimental data are in good agreement for the complex radiation fields generated by all ions incident on shielding for most data points. The differences between model predictions and measurements are discussed. Although improvements are needed, the model extends current capabilities for evaluating beam selection and delivery schemes at the NSRL ground-based GCR simulator and for informing NASA risk projection models in the future.

Bcl2-induced DNA replication stress promotes lung carcinogenesis in response to space radiation.

Space radiation is characterized by high-linear energy transfer (LET) ionizing radiation. The relationships between the early biological effects of space radiation and the probability of cancer in humans are poorly understood. Bcl2 not only functions as a potent antiapoptotic molecule but also as an oncogenic protein that induces DNA replication stress. To test the role and mechanism of Bcl2 in high-LET space radiation-induced lung carcinogenesis, we created lung-targeting Bcl2 transgenic C57BL/6 mice using the CC10 promoter to drive Bcl2 expression selectively in lung tissues. Intriguingly, lung-targeting transgenic Bcl2 inhibits ribonucleotide reductase activity, reduces dNTP pool size and retards DNA replication fork progression in mouse bronchial epithelial cells. After exposure of mice to space radiation derived from 56iron, 28silicon or protons, the incidence of lung cancer was significantly higher in lung-targeting Bcl2 transgenic mice than in wild-type mice, indicating that Bcl2-induced DNA replication stress promotes lung carcinogenesis in response to space radiation. The findings provide some evidence for the relative effectiveness of space radiation and Bcl-2 at inducing lung cancer in mice.

Comments on "New Concerns for Neurocognitive Function during Deep Space Exposures to Chronic, Low Dose Rate, Neutron Radiation".

Evaluations of the biological effects of space radiation must carefully consider the biological system response and the specific nature of the source term. Acharya et al. (2019) review neurocognitive function during deep space exposures to chronic, low dose rate, neutron radiation, but do not use a source term that reflects the actual space environment in terms of radiation types and their respective energies. In addition, important biological effects, including the adaptive response to the space radiation environment, are not addressed.

Role of High-Linear Energy Transfer Radiobiology in Space Radiation Exposure Risks.

Many manned missions to the Moon and Mars are scheduled in the near future. However, space radiation presents a major hazard to humans, and astronauts are constantly exposed to radiation, including high linear energy transfer (LET) radiation, which differs from radiation on Earth. Thus, there is thus an urgent need to clarify the biological effects of space radiation and reduce the associated risks. In this review, we consider the role of high-LET radiobiology in relation to space-radiation exposure.

Detection of DNA damage by space radiation in human fibroblasts flown on the International Space Station

Although charged particles in space have been detected with radiation detectors on board spacecraft since the discovery of the Van Allen Belts, reports on the effects of direct exposure to space radiation in biological systems have been limited. Measurement of biological effects of space radiation is challenging due to the low dose and low dose rate nature of the radiation environment, and due to the difficulty in distinguishing the radiation effects from microgravity and other space environmental factors. In astronauts, only a few changes, such as increased chromosome aberrations in their lymphocytes and early onset of cataracts, are attributed primarily to their exposure to space radiation. In this study, cultured human fibroblasts were flown on the International Space Station (ISS). Cells were kept at 37°C in space for 14 days before being fixed for analysis of DNA damage with the γ-H2AX assay. The 3-dimensional γ-H2AX foci were captured with a laser confocal microscope. Quantitative analysis revealed several foci that were larger and displayed a track pattern only in the Day 14 flight samples. To confirm that the foci data from the flight study was actually induced from space radiation exposure, cultured human fibroblasts were exposed to low dose rate γ rays at 37°C. Cells exposed to chronic γ rays showed similar foci size distribution in comparison to the non-exposed controls. The cells were also exposed to low- and high-LET protons, and high-LET Fe ions on the ground. Our results suggest that in G1 human fibroblasts under the normal culture condition, only a small fraction of large size foci can be attributed to high-LET radiation in space.

BioSentinel: A 6U Nanosatellite for Deep-Space Biological Science

BioSentinel is a 6U nanosatellite planned to launch in 2020 as a secondary payload onboard NASA's Space Launch System first exploration mission, Artemis-1, from which it will be deployed to a lunar fly-by trajectory leading to a heliocentric orbit. BioSentinel will conduct the first in situ measurements of biological response to space radiation outside low Earth orbit (LEO) in five decades; it will thus address strategic knowledge gaps related to the biological effects of space radiation. BioSentinel will measure the DNA damage and response to ambient space radiation in a model biological organism, which will be compared to information provided by an onboard physical radiation sensor and to data obtained in LEO (on the International Space Station) and on Earth. The spacecraft will operate in a deep-space environment with functions that include command and data handling, communications, power generation and energy storage, and attitude determination and control, including micropropulsion. The BioSentinel spacecraft advances multiple nanosatellite systems in order to function beyond LEO; by doing so, it provides an adaptable instrument platform to perform a range of human-exploration-relevant measurements in multiple space environments. BioSentinel's results will be critical for improving interpretation of the biological effects of space radiation exposure, and for reducing the risk to humans associated with long-term space exploration.

Oxygen and Silicon Ion Particles Induce Neoplastic Transformation in Human Colonic Epithelial Cells

ABSTRACT High charge (Z) and energy (E) (HZE) particles in deep space have significantly contributed to the biological effects of space radiation, although they only account for less than 1% of the galactic cosmic rays (GCR) particle fluxes. Previously we have shown that combined radiation exposure of 2-Gy proton (1H) followed by 0.5-Gy iron (56Fe) ion particles increase transformation in human colonic epithelial cells (HCEC CT7). The present study was undertaken to characterize if additional HZE ions, such as oxygen (16O) and silicon (28Si) particles, also result in increased cell transformation. HCEC CT7 cells irradiated with 1-Gy 16O (250 MeV/nucleon), followed 24 hours later by 1-Gy 28Si particle (300 MeV/nucleon), showed an increase in proliferation, anchorage-independent growth, migration, and invasion abilities compared to unirradiated controls. In addition, we found that the β-catenin pathway was activated and that subsets of DNA repair genes were under-expressed in these transformed cells. Pretreatment with the radioprotector, CDDO-Me, 18 hours before and during irradiation prevented the HZE-induced transformation. These results can be interpreted to suggest that the mixed radiation exposure of 16O followed by 28Si has carcinogenic potential. Importantly, this transformation can be protected by CDDO-Me pre-treatment.

Simulated studies on the biological effects of space radiation on quiescent human fibroblasts

High charge and energy (HZE) particles are severe risk to manned long-term outer space exploration. Studies on the biological effects of space HZE particles and the underlying mechanisms are essential to the accurate risk assessment and the development of efficient countermeasure. Since majority of the cells in human body stay quiescent (G0 phase), in this study, we established G0 cell and G1 cell models by releasing human normal embryonic lung fibroblast cells from contact inhibition and studied the radiation toxicity of various kinds of HZE particles. Results showed that all of the particles were dose-dependently lethal and G0 cells were more radioresistant than G1 cells. We also found that 53BP1 foci were induced in a LET- and fluence-dependent manner and fewer foci were induced in G0 cells than G1 cells, however, the decrease of foci in 24h after irradiation was highly relevant to the type of particles. These results imply that even though health risk of space radiation is probably overestimated by the data obtained with exponentially growing cells, whose radiosensitivity is similar to G1 cells, the risk of space HZE particles is un-ignorable and accurate assessment and mechanistic studies should be deepened. The diverse abilities of G0 cells and G1 cells in repairing DNA damages induced by HZE particles emphasize the importance in studying the impact of HZE particles on DNA damage repair pathways.

Effects of shielding on the induction of 53BP1 foci and micronuclei after Fe ion exposures

High atomic number and high-energy (HZE) particles in deep space are of low abundance but substantially contribute to the biological effects of space radiation. Shielding is so far the most effective way to partially protect astronauts from these highly penetrating particles. However, simulated calculations and measurements have predicted that secondary particles resulting from the shielding of cosmic rays produce a significant fraction of the total dose and dose equivalent. In this study, we investigated the biological effects of secondary radiation with two cell types, and with cells exposed in different phases of the cell cycle, by comparing the biological effects of a 200 MeV/u iron beam with a shielded beam in which the energy of the iron ion beam was decreased from 500 MeV/u to 200 MeV/u with PMMA, polyethylene (PE), or aluminum. We found that beam shielding resulted in increased induction of 53BP1 foci and micronuclei in a cell-type-dependent manner compared with the unshielded 200 MeV/u Fe ion beam. These findings provide experimental proof that the biological effects of secondary particles resulting from the interaction between HZE particles and shielding materials should be considered in shielding design.

The CRaTER Special Issue of Space Weather: Building the observational foundation to deduce biological effects of space radiation

Key Points Need for validated measurements of radiation environment

In Vivo Space Radiation-Induced Non-Targeted Responses: Late Effects on Molecular Signaling in Mitochondria

The lack of clear knowledge about space radiation-induced biological effects has been singled out as the most important factor limiting the prediction of radiation risk associated with human space exploration. The expression of space radiation-induced non-targeted effects is thought to impact our understanding of the health risks associated with exposure to low fluences of particulate radiation encountered by astronauts during prolonged space travel. Following a brief review of radiation-induced bystander effects and the growing literature for the involvement of oxidative metabolism in their expression, we show novel data on the induction of in vivo non-targeted effects following exposure to 1100 MeV/nucleon titanium ions. Analyses of proteins by two-dimensional gel electrophoresis in non-targeted liver of cranially-irradiated Sprague Dawley rats revealed that the levels of key proteins involved in mitochondrial fatty acid metabolism are decreased. In contrast, those of proteins involved in various cellular defense mechanisms, including antioxidation, were increased. These data contribute to our understanding of the mechanisms underlying the biological responses to space radiation, and support the involvement of mitochondrial processes in the expression of radiation induced non-targeted effects. Significantly, they reveal the cross-talk between propagated stressful effects and induced adaptive responses. Together, with the accumulating data in the field, our results may help reduce the uncertainty in the assessment of the health risks to astronauts. They further demonstrate that ‘network analyses’ is an effective tool towards characterizing the signaling pathways that mediate the long-term biological effects of space radiation. Keywords: High charge and high energy particles, ionizing radiation, liver, mitochondria, non-targeted responses, oxidative metabolism, space radiation, Mass spectrometry, Mitochondrial DNA, Reactive oxygen species

In Vivo Space Radiation-Induced Non-Targeted Responses: Late Effects on Molecular Signaling in Mitochondria

The lack of clear knowledge about space radiation-induced biological effects has been singled out as the most important factor limiting the prediction of radiation risk associated with human space exploration. The expression of space radiation-induced non-targeted effects is thought to impact our understanding of the health risks associated with exposure to low fluences of particulate radiation encountered by astronauts during prolonged space travel. Following a brief review of radiation-induced bystander effects and the growing literature for the involvement of oxidative metabolism in their expression, we show novel data on the induction of in vivo non-targeted effects following exposure to 1100 MeV/nucleon titanium ions. Analyses of proteins by two-dimensional gel electrophoresis in non-targeted liver of cranially-irradiated Sprague Dawley rats revealed that the levels of key proteins involved in mitochondrial fatty acid metabolism are decreased. In contrast, those of proteins involved in various cellular defense mechanisms, including antioxidation, were increased. These data contribute to our understanding of the mechanisms underlying the biological responses to space radiation, and support the involvement of mitochondrial processes in the expression of radiation induced non-targeted effects. Significantly, they reveal the cross-talk between propagated stressful effects and induced adaptive responses. Together, with the accumulating data in the field, our results may help reduce the uncertainty in the assessment of the health risks to astronauts. They further demonstrate that 'network analyses' is an effective tool towards characterizing the signaling pathways that mediate the long-term biological effects of space radiation.

Biological Effects of Space Radiation on Human Cells: History, Advances and Outcomes

Exposure to radiation is one of the main concerns for space exploration by humans. By focusing deliberately on the works performed on human cells, we endeavored to review, decade by decade, the technological developments and conceptual advances of space radiation biology. Despite considerable efforts, the cancer and the toxicity risks remain to be quantified: 1) the nature and the frequency of secondary heavy ions need to be better characterized in order to estimate their contribution to the dose and to the final biological response; 2) the diversity of radiation history of each astronaut and the impact of individual susceptibility make very difficult any epidemiological analysis for estimating hazards specifically due to space radiation exposure. 3) Cytogenetic data undoubtedly revealed that space radiation exposure produce significant damage in cells. However, our knowledge of the basic mechanisms specific to low-dose, to repeated doses and to adaptive response is still poor. The application of new radiobiological techniques, like immunofluorescence, and the use of human tissue models different from blood, like skin fibroblasts, may help in clarifying all the above items.

Simulations of the MATROSHKA experiment at the international space station using PHITS

Concerns about the biological effects of space radiation are increasing rapidly due to the perspective of long-duration manned missions, both in relation to the International Space Station (ISS) and to manned interplanetary missions to Moon and Mars in the future. As a preparation for these long-duration space missions, it is important to ensure an excellent capability to evaluate the impact of space radiation on human health, in order to secure the safety of the astronauts/cosmonauts and minimize their risks. It is therefore necessary to measure the radiation load on the personnel both inside and outside the space vehicles and certify that organ- and tissue-equivalent doses can be simulated as accurate as possible. In this paper, simulations are presented using the three-dimensional Monte Carlo Particle and Heavy-Ion Transport code System (PHITS) (Iwase et al. in J Nucl Sci Tech 39(11):1142-1151, 2002) of long-term dose measurements performed with the European Space Agency-supported MATROSHKA (MTR) experiment (Reitz and Berger in Radiat Prot Dosim 120:442-445, 2006). MATROSHKA is an anthropomorphic phantom containing over 6,000 radiation detectors, mimicking a human head and torso. The MTR experiment, led by the German Aerospace Center (DLR), was launched in January 2004 and has measured the absorbed doses from space radiation both inside and outside the ISS. Comparisons of simulations with measurements outside the ISS are presented. The results indicate that PHITS is a suitable tool for estimation of doses received from cosmic radiation and for study of the shielding of spacecraft against cosmic radiation.

Monte Carlo analysis of pion contribution to absorbed dose from Galactic cosmic rays

Accurate knowledge of the physics of interaction, particle production and transport is necessary to estimate the radiation damage to equipment used on spacecraft and the biological effects of space radiation. For long duration astronaut missions, both on the International Space Station and the planned manned missions to Moon and Mars, the shielding strategy must include a comprehensive knowledge of the secondary radiation environment. The distribution of absorbed dose and dose equivalent is a function of the type, energy and population of these secondary products. Galactic cosmic rays (GCR) comprised of protons and heavier nuclei have energies from a few MeV per nucleon to the ZeV region, with the spectra reaching flux maxima in the hundreds of MeV range. Therefore, the MeV–GeV region is most important for space radiation. Coincidentally, the pion production energy threshold is about 280 MeV. The question naturally arises as to how important these particles are with respect to space radiation problems. The space radiation transport code, HZETRN (High charge (Z) and Energy TRaNsport), currently used by NASA, performs neutron, proton and heavy ion transport explicitly, but it does not take into account the production and transport of mesons, photons and leptons. In this paper, we present results from the Monte Carlo code MCNPX (Monte Carlo N-Particle eXtended), showing the effect of leptons and mesons when they are produced and transported in a GCR environment.