Histological and Transcriptomic Analysis of Adult Japanese Medaka Sampled Onboard the International Space Station

To understand how humans adapt to the space environment, many experiments can be conducted on astronauts as they work aboard the Space Shuttle or the International Space Station (ISS). We also need animal experiments that can apply to human models and help prevent or solve the health issues we face in space travel. The Japanese medaka (Oryzias latipes) is a suitable model fish for studying space adaptation as evidenced by adults of the species having mated successfully in space during 15 days of flight during the second International Microgravity Laboratory mission in 1994. The eggs laid by the fish developed normally and hatched as juveniles in space. In 2012, another space experiment (“Medaka Osteoclast”) was conducted. Six-week-old male and female Japanese medaka (Cab strain osteoblast transgenic fish) were maintained in the Aquatic Habitat system for two months in the ISS. Fish of the same strain and age were used as the ground controls. Six fish were fixed with paraformaldehyde or kept in RNA stabilization reagent (n = 4) and dissected for tissue sampling after being returned to the ground, so that several principal investigators working on the project could share samples. Histology indicated no significant changes except in the ovary. However, the RNA-seq analysis of 5345 genes from six tissues revealed highly tissue-specific space responsiveness after a two-month stay in the ISS. Similar responsiveness was observed among the brain and eye, ovary and testis, and the liver and intestine. Among these six tissues, the intestine showed the highest space response with 10 genes categorized as oxidation–reduction processes (gene ontogeny term GO:0055114), and the expression levels of choriogenin precursor genes were suppressed in the ovary. Eleven genes including klf9, klf13, odc1, hsp70 and hif3a were upregulated in more than four of the tissues examined, thus suggesting common immunoregulatory and stress responses during space adaptation.     

Shuttle radiation dose measurements in the International Space Station orbits.

The International Space Station (ISS) is now a reality with the start of a permanent human presence on board. Radiation presents a serious risk to the health and safety of the astronauts, and there is a clear requirement for estimating their exposures prior to and after flights. Predictions of the dose rate at times other than solar minimum or solar maximum have not been possible, because there has been no method to calculate the trapped-particle spectrum at intermediate times. Over the last few years, a tissue-equivalent proportional counter (TEPC) has been flown at a fixed mid-deck location on board the Space Shuttle in 51.65 degrees inclination flights. These flights have provided data that cover the expected changes in the dose rates due to changes in altitude and changes in solar activity from the solar minimum to the solar maximum of the current 23rd solar cycle. Based on these data, a simple function of the solar deceleration potential has been derived that can be used to predict the galactic cosmic radiation (GCR) dose rates to within +/-10%. For altitudes to be covered by the ISS, the dose rate due to the trapped particles is found to be a power-law function, rho(-2/3), of the atmospheric density, rho. This relationship can be used to predict trapped dose rates inside these spacecraft to +/-10% throughout the solar cycle. Thus, given the shielding distribution for a location inside the Space Shuttle or inside an ISS module, this approach can be used to predict the combined GCR + trapped dose rate to better than +/-15% for quiet solar conditions.     

Columbus, the European Physiology Modules Facility and CADMOS

Columbus, the European Space Agency (ESA) orbital facility laboratory will be launched in December 2007 and attached to the International Space Station (ISS). In its launch configuration, Columbus includes 4 multi-user facilities: one of them is the European Physiology Modules Facility, also called EPM. The EPM will be devoted to Human Physiology; it will be collocated in the Columbus module with two other physiology racks, i.e. the HRF-1 and HRF-2 American racks (Human Research Facility). CADMOS is part of the French Space Agency, located in Toulouse; it has been designated by the European Space Agency as the Facility Responsible Centre (FRC) for the EPM. As a User Support and Operations Centre, CADMOS main tasks are to help the scientists to prepare and perform their experiments in Space and to monitor operations on the ISS.     

Microbe-I: fungal biota analyses of the Japanese experimental module KIBO of the International Space Station before launch and after being in orbit for about 460 days

In addition to the crew, microbes also find their way aboard the International Space Station (ISS). Therefore, microbial monitoring is necessary for the health and safety of the crew and for general maintenance of the facilities of this station. Samples were collected from three sites in the Japanese experimental module KIBO on the ISS (air diffuser, handrail, and surfaces) for analysis of fungal biota approximately 1 year after this module had docked with the ISS. Samples taken from KIBO before launch and from our laboratory were used as controls. In the case of KIBO, both microbe detection sheet (MDS) and swab culture tests of orbital samples were negative. The MDS were also examined by field emission-scanning electron microscopy; no microbial structures were detected. However, fungal DNAs were detected by real-time PCR and analyzed by the clone library method; Alternaria sp. and Malassezia spp. were the dominant species before launch and in space, respectively. The dominant species found in specimens from the air conditioner diffuser, lab bench, door push panel, and facility surfaces on our laboratory (ground controls) were Inonotus sp., Cladosporium sp., Malassezia spp., and Pezicula sp., respectively. The fungi in the KIBO were probably derived from contamination due to humans, while those in our laboratory came from the environment (e.g., the soil). In conclusion, the cleanliness in KIBO was equivalent to that in a clean room environment on the ground.     

Lipid peroxidation rate and the antioxidant protection system during the readaptation period after long-term space flights on board the International Space Station

The content of lipid peroxidation (LPO) products (diene conjugates (DC), malondialdehyde (MDA), Schiff bases (SB), and tocopherol (TP, a main lipid antioxidant) were measured in blood serum of 17 astronauts taking part in long-term (125–217 days) missions on board the International Space Station (ISS) during the preflight period, on the day of the landing, and on the 7th and 14th days after landing (the rehabilitation period, RP). A decrease in the DC and MDA levels against a background of an increase in TP has been found in a group of eight astronauts after landing on board the Space Shuttle spacecraft and a group of eight astronauts after a space flight on board the Soyuz TM in the course of RP. The changes in measured indices were more pronounced in the group of astronauts after the space flight on board the Space Shuttle spacecraft. Inhibition of LPO during RP was regarded as an adequate response to readaptation stress to the conditions on earth. The possible mechanisms of differences in the efficiency of LPO inhibition between groups are discussed: the changes in the biomembrane phase state under the conditions of deceleration load during disorbiting and the stressful reaction to landing on board different spacecrafts.     

Effects of a Closed Space Environment on Gene Expression in Hair Follicles of Astronauts in the International Space Station

Adaptation to the space environment can sometimes pose physiological problems to International Space Station (ISS) astronauts after their return to earth. Therefore, it is important to develop healthcare technologies for astronauts. In this study, we examined the feasibility of using hair follicles, a readily obtained sample, to assess gene expression changes in response to spaceflight adaptation. In order to investigate the gene expression changes in human hair follicles during spaceflight, hair follicles of 10 astronauts were analyzed by microarray and real time qPCR analyses. We found that spaceflight alters human hair follicle gene expression. The degree of changes in gene expression was found to vary among individuals. In some astronauts, genes related to hair growth such as FGF18, ANGPTL7 and COMP were upregulated during flight, suggesting that spaceflight inhibits cell proliferation in hair follicles.     

The effects of weightlessness on the human organism and mammalian cells

It has always been a desire of mankind to conquest Space. A major step in realizing this dream was the completion of the International Space Station (ISS). Living there for several months confirmed early observations of short-term spaceflights that a loss of gravity affects the health of astronauts. Space medicine tries to understand the mechanism of microgravity-induced health problems and to conceive potent countermeasures. There are four different aspects which make space medicine appealing: i) finding better strategies for adapting astronauts to weightlessness; ii) identification of microgravity-induced diseases (e.g. osteoporosis, muscle atrophy, cardiac problems and others); iii) defining new therapies to conquer these diseases which will benefit astronauts as well as people on Earth in the end; and iv) on top of that, unveiling the mechanisms of weightlessness-dependent molecular and cellular changes is a requirement for improving space medicine. In mammalian cells, microgravity induces apoptosis and alters the cytoskeleton and affects signal transduction pathways, cell differentiation, growth, proliferation, migration and adhesion. This review focused on gravi-sensitive signal transduction elements and pathways as well as molecular mechanisms in human cells, aiming to understand the cellular changes in altered gravity. Moreover, the latest information on how these changes lead to clinically relevant health problems and current strategies of countermeasures are reviewed.     

Physical and biological organ dosimetry analysis for international space station astronauts

In this study, we analyzed the biological and physical organ dose equivalents for International Space Station (ISS) astronauts. Individual physical dosimetry is difficult in space due to the complexity of the space radiation environment, which consists of protons, heavy ions and secondary neutrons, and the modification of these radiation types in tissue as well as limitations in dosimeter devices that can be worn for several months in outer space. Astronauts returning from missions to the ISS undergo biodosimetry assessment of chromosomal damage in lymphocyte cells using the multicolor fluorescence in situ hybridization (FISH) technique. Individual-based pre-flight dose responses for lymphocyte exposure in vitro to gamma rays were compared to those exposed to space radiation in vivo to determine an equivalent biological dose. We compared the ISS biodosimetry results, NASA's space radiation transport models of organ dose equivalents, and results from ISS and space shuttle phantom torso experiments. Physical and biological doses for 19 ISS astronauts yielded average effective doses and individual or population-based biological doses for the approximately 6-month missions of 72 mSv and 85 or 81 mGy-Eq, respectively. Analyses showed that 80% or more of organ dose equivalents on the ISS are from galactic cosmic rays and only a small contribution is from trapped protons and that GCR doses were decreased by the high level of solar activity in recent years. Comparisons of models to data showed that space radiation effective doses can be predicted to within about a +/-10% accuracy by space radiation transport models. Finally, effective dose estimates for all previous NASA missions are summarized.     

Updates to astronaut radiation limits: radiation risks for never-smokers

New epidemiology assessments of the life span study (LSS) of the atomic bomb survivors in Japan and of other exposed cohorts have been made by the U.S. National Academy of Sciences, the United Nations Committee on the Effects of Atomic Radiation, and the Radiation Research Effects Foundation in Japan. The National Aeronautics and Space Administration (NASA) uses a 3% risk of exposure-induced death (REID) as a basis for setting age- and gender-specific dose limits for astronauts. NASA's dose limits originate from the report of the National Council on Radiation Protection and Measurements (NCRP) in the year 2000 based on analysis of older epidemiology data. We compared the results of the recent analysis of the LSS to the earlier risk projections from the NCRP. Using tissue-specific, incidence-based risk transfer from the LSS data to a U.S. population to project REID values leads to higher risk and reduced dose limits for older astronauts (>40 years) compared to earlier models that were based on mortality risk transfer. Because astronauts and many other individuals should be considered as healthy workers, including never-smokers free of lifetime use of tobacco, we considered possible variations in risks and dose limits that would occur due to the reference population used for estimates. After adjusting cancer rates to remove smoking effects, radiation risks for lung and total cancer were estimated using a mixture model, with equal weights for additive and multiplicative transfer, to be 20% and 30% lower for males and females, respectively, for never-smokers compared to the average U.S. population. We recommend age- and gender-specific dose limits based on incidence-based risk transfer for never-smokers that could be used by NASA. Our analysis illustrates that gaining knowledge to improve transfer models, which entail knowledge of cancer initiation and promotion effects, could significantly reduce uncertainties in risk projections.     

A study of orientation in a zero gravity environment by means of virtual reality simulation

When the International Space Station (ISS) is completed and starts its operation, crew members will be stationed for three months or more in orbit aboard the ISS. As they stay longer in the space environment, "habitability" for them will become most important in the design of the interior space. One of the problems about habitability in a zero gravity (0 G) environment is disorientation. Crew members have difficulty in discriminating between "up" and "down" and more serious disorientations may cause space motion sickness. Crew members rely on visual perception to orient themselves because they can't use their sense of equilibrium in a 0 G environment. Although color and the direction of equipment of Space Shuttles or modules has been considered, no systematic study has been conducted on interior space. This study intended to clarify how people acquire visual information and recognize their orientation in a 0 G environment by an experiment in which a subject wears a head-mounted display (HMD) and enters a virtual weightless state represented by computer graphics (CG). Visual information of a room and the degree-of-freedom of motion were varied to examine the influence of the conditions on such a simple task as movement through several connected modules, and the performance and the behavior of each subject were investigated.     

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.     

Foot forces during typical days on the international space station

Decreased bone mineral density (BMD) in astronauts returning from long-duration spaceflight missions has been well documented, but the altered mechanical loading environment experienced by the musculoskeletal system, which may contribute to these changes, has not been well characterized. The current study describes the loading environment of the lower extremity (LE) during typical days on the International Space Station (ISS) compared to similar data for the same individuals living on Earth. Data from in-shoe force measurements are also used as input to the enhanced daily load stimulus (EDLS) model to determine the mechanical “dose” experienced by the musculoskeletal system and to associate this dose with changes in BMD.Four male astronauts on approximately 6-month missions to the ISS participated in this study. In-shoe forces were recorded using capacitance-based insoles during entire typical working days both on Earth and on-orbit. BMD estimates from the hip and spine regions were obtained from dual energy X-ray absorptiometry (DXA) pre- and post-flight.Measurable loading was recorded for only 30% of the time assigned for exercise. In-shoe forces during treadmill walking and running on the ISS were reduced by 25% and 46%, respectively, compared to similar activities on Earth. Mean on-orbit LE loads varied from 0.20 to 1.3 body weight (BW) during resistance exercise and were ～0.10 BW during bicycle ergometry. Application of the EDLS model showed a mean decrease of 25% in the daily load experienced by the LE. BMD decreased by 0.71% and 0.83% per month during their missions in the femoral neck and lumbar spine, respectively.Our findings support the conclusion that the measured ISS exercise durations and/or loading were insufficient to provide the loading stimulus required to prevent bone loss. Future trials with EDLS values closer to 100% of Earth values will offer a true test of exercise as a countermeasure to on-orbit bone loss.     

STS-95 Space Experiments (plants and cell biology).

We report the outline of Space Experiments conducted on Space Shuttle (STS-95) launched in autumn of 1998. In this STS-95 mission, Japanese astronaut Dr. Chiaki Mukai achieved her 2nd space flight and conducted a part of 82 space experiments including Japanese experiments. US astronaut Senator John Glenn also achieved his second space flight, 36 years after his first space flight. Senator Glenn was a leader of the original (the first) 7 US astronauts and very famous in US because he succeeded US first orbital space flight around the earth. NASDA had started the project of space experiment using STS-95 at the summer of 1997, therefore we had only one year for the all preparation Yamashita, et al. Biological Sciences in Space, Vol.12 No.3(1998). Scientific results will be reported by investigators, therefore we report here how we had been developing the space experiment plan, on board operation procedure and ground operations including ground control experiments about four plant experiments and one cell biology experiment.     

Developing protocols for recombinant adeno-associated virus-mediated gene therapy in space

With the advent of the era of International Space Station (ISS) and Mars exploration, it is important more than ever to develop means to cure genetic and acquired diseases, which include cancer and AIDS, for these diseases hamper human activities. Thus, our ultimate goal is to develop protocols for gene therapy, which are suitable to humans on the earth as well as in space. Specifically, we are trying to cure the hemoglobinopathies, beta-thalassemia (Cooley's anemia) and sickle cell anemia, by gene therapy. These well-characterized molecular diseases serve as models for developing ex vivo gene therapy, which would apply to other disorders as well. For example, the procedure may become directly relevant to treating astronauts for space-anemia, immune suppression and bone marrow derived tumors, e.g. leukemia. The adeno-associated virus serotype 2 (AAV2) is a non-pathogenic human parvovirus with broad host-range and tissue specificity. Exploiting these characteristics we have been developing protocols for recombinant AAV2 (rAAV)-based gene therapy. With the rAAV constructs and hematopoietic stem cell (HSC) culture systems in hand, we are currently attempting to cure the mouse model of beta-thalassemia [C57BL/6- Hbbth/Hbbth, Hb(d-minor)] by HSC transplantation (HST) as well as by gene therapy. This paper describes the current status of our rAAV-gene therapy research.     

NUNDO: a numerical model of a human torso phantom and its application to effective dose equivalent calculations for astronauts at the ISS

The health effects of cosmic radiation on astronauts need to be precisely quantified and controlled. This task is important not only in perspective of the increasing human presence at the International Space Station (ISS), but also for the preparation of safe human missions beyond low earth orbit. From a radiation protection point of view, the baseline quantity for radiation risk assessment in space is the effective dose equivalent. The present work reports the first successful attempt of the experimental determination of the effective dose equivalent in space, both for extra-vehicular activity (EVA) and intra-vehicular activity (IVA). This was achieved using the anthropomorphic torso phantom RANDO^® equipped with more than 6,000 passive thermoluminescent detectors and plastic nuclear track detectors, which have been exposed to cosmic radiation inside the European Space Agency MATROSHKA facility both outside and inside the ISS. In order to calculate the effective dose equivalent, a numerical model of the RANDO^® phantom, based on computer tomography scans of the actual phantom, was developed. It was found that the effective dose equivalent rate during an EVA approaches 700 μSv/d, while during an IVA about 20 % lower values were observed. It is shown that the individual dose based on a personal dosimeter reading for an astronaut during IVA results in an overestimate of the effective dose equivalent of about 15 %, whereas under an EVA conditions the overestimate is more than 200 %. A personal dosemeter can therefore deliver quite good exposure records during IVA, but may overestimate the effective dose equivalent received during an EVA considerably.     

Some aspects of the comparative analysis of hemodynamic responses to LBNP tests in cosmonauts of different age groups

The age-specific indicators of the functions of the cardiovascular system and its responses to the lower body negative pressure (LBNP) test were studied in career cosmonauts for the first time. The results of 174 LBNP tests implemented within the standard medical monitoring program on board the ??Mir?? orbital station (OS ??Mir??), using a Gamma-01 device, and aboard the International Space Station (ISS), using the Gamma-1M complex, were subjected to comparative analysis. In total, 38 cosmonauts from 25 long-duration space missions on board the ??Mir?? OS and ISS, who were examined in their pre-flight state and during in-flight periods, beginning, typically, on flight day (FD) 120, were subdivided into two age groups: 30- to 39-year-olds (their mean age was 36 ± 0.7 years; 39% of the total number of subjects) and 40- to 55-year olds (their mean age was 46 ± 0.8 years; 61% of the total number of subjects). We have revealed age-specific indicators for the hemodynamic status recorded at each stage of the investigation: at rest in a preflight state; responses of the indicators to the effects of microgravity; the relative dynamics of the indicators due to a simulated orthostatic posture, which was unidirectional but substantially different at the pre-and in-flight stages. For purposes of medical control, our results have shown that we need to establish age-specific references in our methodical approaches to the analysis and interpretation of the data received from monitoring cosmonauts?? health in their preflight state and during the entire mission and, which is particularly important in practical terms, when evaluating the LBNP test intolerance at different flight stages.     

Issues in protection from galactic cosmic rays

Radiation risks to astronauts depend on the microscopic fluctuations of energy absorption events in specific tissues. These fluctuations depend not only on the space environment but also on the modifications of that environment by the shielding provided by structures surrounding the astronauts and the attenuation characteristics of the astronaut's body. The effects of attenuation within the shield and body depends on the tissue biological response to these microscopic fluctuations. In the absence of an accepted method for estimating astronaut risk, we examined the attenuation characteristics using conventional linear energy transfer (LET)-dependent quality factors (as one means of representing relative biological effectiveness, RBE) and a track-structure repair model to fit cell transformation (and inactivation) data in the C3H10 T1/2 mouse cell system obtained for various ion beams. Although the usual aluminum spacecraft shield is effective in reducing dose equivalent with increasing shield thickness, cell transformation rates are increased for thin aluminum shields. Clearly, the exact nature of the biological response to LET and track width is critical to evaluation of biological protection factors provided by a shield design. A significant fraction of biological injury results from the LET region above 100 keV/µm. Uncertainty in nuclear cross-sections results in a factor of 2–3 in the transmitted LET spectrum beyond depths of 15 g/cm², but even greater uncertainty is due to the combined effects of uncertainty in biological response and nuclear parameters. Clearly, these uncertainties must be reduced before the shield design can be finalised.Submitted paper presented at the International Symposium on Heavy Ion Research: Space, Radiation Protection and Therapy, Sophia-Antipolis, France, 21–24 March 1994     

Intraspecific differences in bacterial responses to modelled reduced gravity

AIMS: Bacteria are important residents of water systems, including those of space stations which feature specific environmental conditions, such as lowered effects of gravity. The purpose of this study was to compare responses with modelled reduced gravity of space station, water system bacterial isolates with other isolates of the same species. METHODS AND RESULTS: Bacterial isolates, Stenotrophomonas paucimobilis and Acinetobacter radioresistens, originally recovered from the water supply aboard the International Space Station (ISS) were grown in nutrient broth under modelled reduced gravity. Their growth was compared with type strains S. paucimobilis ATCC 10829 and A. radioresistens ATCC 49000. Acinetobacter radioresistens ATCC 49000 and the two ISS isolates showed similar growth profiles under modelled reduced gravity compared with normal gravity, whereas S. paucimobilis ATCC 10829 was negatively affected by modelled reduced gravity. CONCLUSIONS: These results suggest that microgravity might have selected for bacteria that were able to thrive under this unusual condition. These responses, coupled with impacts of other features (such as radiation resistance and ability to persist under very oligotrophic conditions), may contribute to the success of these water system bacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: Water quality is a significant factor in many environments including the ISS. Efforts to remove microbial contaminants are likely to be complicated by the features of these bacteria which allow them to persist under the extreme conditions of the systems.     

Characterization of the Survival Ability of Cupriavidus metallidurans and Ralstonia pickettii from Space-Related Environments

Four Cupriavidus metallidurans and eight Ralstonia pickettii isolates from the space industry and the International Space Station (ISS) were characterized in detail. Nine of the 12 isolates were able to form a biofilm on plastics and all were resistant to several antibiotics. R. pickettii isolates from the surface of the Mars Orbiter prior to flight were 2.5 times more resistant to UV-C_254nm radiation compared to the R. pickettii type strain. All isolates showed moderate to high tolerance against at least seven different metal ions. They were tolerant to medium to high silver concentrations (0.5–4 μM), which are higher than the ionic silver disinfectant concentrations measured regularly in the drinking water aboard the ISS. Furthermore, all isolates survived a 23-month exposure to 2 μM AgNO₃ in drinking water. These resistance properties are putatively encoded by their endogenous megaplasmids. This study demonstrated that extreme resistance is not required to withstand the disinfection and sterilization procedures implemented in the ISS and space industry. All isolates acquired moderate to high tolerance against several stressors and can grow in oligotrophic conditions, enabling them to persist in these environments.