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NASA NTRS2017

The Effects of CDKN1a/p21 on Oxidative Stress and Mitochondrial Function During Long Duration Spaceflight

Spaceflight factors, such as microgravity and space radiation, are known to put astronauts at risk for negative effects to their tissue regeneration and degenerative conditions. On our previous spaceflight research, we found that long duration spaceflight produced increased oxidative stress and activation of the inflammatory response as a major contributor to physiological changes, including alterations to the cardiovascular and musculoskeletal systems, metabolism, and the liver. Proliferation, apoptosis, and ion-channel remodeling of vascular smooth muscle cells, as well as endothelial inflammation, and nitric oxide synthase-nitric oxide system regulation have been shown by spaceflight and simulated spaceflight projects. CDKN1ap21 is a regulatory gene for tissue regeneration and also plays an important role in upregulating oxidative stress caused by radiation. In further research, we have also determined CDKN1ap21 to be overexpressed during spaceflight. When knocked out in mice, however, it protects against unloading-induced changes to the morphology and physiology of carotid arteries. In this proposal, we seek to test a potential dietary countermeasure to down-regulate CDKN1ap21 in the mice and protect against oxidative stress in the rodents. Specifically, we will expose both Wildtype and CDKN1ap21-null mice to hydrogen peroxide to induce oxidative stress and observe the molecular mechanisms in which a dietary supplement protects vascular smooth muscle cells against the consequences of the apoptotic environment within Wildtype mice versus the, hypothetically, sound physiology of CDKN1ap21-null mice. The successful completion of this experiment will conclusively determine accuracy of a dietary supplement as a CDKN1ap21 suppressor. This will provide a new perspective on the problem of increased oxidative stress developing into cardiovascular disease as a result of long-term space flight. This research will address the Human Research Plan Roadmaps Risk of Cardiac Rhythm Problems including CV-8, the Risk of Cardiovascular Disease and Other Degenerative Tissue Effects from Radiation Exposure including Degen-6 and Degen-7, and the Risk of Adverse Health Event from Radiation Exposure including IM-8. Additionally, this research will address Space Biology Research Plans questions SBP CMB-1, SBP CMB-3, and SB AN-2.

Oxidative Stress↗

NASA NTRS2019

Effects of Spaceflight and Simulated Microgravity on a Host-Pathogen System

While evidence suggests that astronauts and cosmonauts suffer from immune disorders both during and after spaceflight, the underlying causes are still poorly understood, due in part to the fact that there are so many variables to consider when investigating the human immune system in a complex environment. Furthermore, research has shown that common human pathogens also become more virulent after experiencing spaceflight, which can be especially concerning in the context of potentially immunocompromised astronauts. Invertebrates have become popular models for studying human disease because they have immune systems with a high genetic similarity to humans. Recently, the common bacterial pathogen Serratia marcescens was shown to become more lethal to the fruit fly, Drosophila melanogaster, after being cultured in space, suggesting that not only do we need to consider host changes in susceptibility, but also changes in the pathogen itself after exposure to spaceflight conditions. Being able to simulate spaceflight conditions in a controlled environment on the ground gives us the ability to understand how the microorganisms that cause immune disorders are being affected by these drastic environmental shifts. In this study, I use both spaceflight and Low-shear modeled microgravity (LSMMG) environments to examine the genetic changes associated with increased S. marcescens virulence in order to understand how microgravity is affecting this pathogen, as well as how these genetic changes influence and interact with the host immune system. I also examined the effects of nutrient composition and altered growth conditions on the LSMMG-induced increase in virulence, as well as changes in gene expression mediated by both nutrient composition and exposure to LSMMG. This study will provide us with more directed approaches to studying the effects of spaceflight on human beings, with the ultimate goal of being able to prevent human immune dysfunction in future space exploration.

Gilbert, Rachel↗

NASA NTRSDate not supplied

Circulating miRNA Signature Predicts and Rescues Spaceflight Associated Health Risks

We have identified and validated a spaceflight-associated microRNA (miRNA) signature that is shared by rodents and humans in response to simulated and real spaceflight and regulates vascular damage by simulated deep space radiation. In previous studies, we identified miRNAs that are predicted to regulate rodent responses to spaceflight in low-Earth orbit. Here we have validated the expression of key spaceflight-associated miRNAs in rodents reacting to simulated spaceflight conditions (exposure to ionizing radiation combined with simulated microgravity) and in astronaut samples from the NASA Twin Study. We demonstrate that this circulating miRNA siganture is conserved between these different species and will serve as an ideal biomarker to monitor increase health risk due to exposure to the space environment. Lastly, to demonstrate their physiological relevance, we have utilized antagomirs to target a subset of miRNAs from the spaceflight associated signature to successfully rescue simulated deep space radiation-mediated damage in human 3D vascular constructs. These results provide strong evidence to further develop a miRNA based countermeasure in astronauts.

Afshin Beheshti↗

NASA NTRS2020

Circulating Mirna Spaceflight Signature Reveals Targets to Mitigate Associated Health Risks

We have identified and validated a spaceflight-associated microRNA (miRNA) signature that is shared by rodents and humans in response to simulated, short-duration, and long-duration spaceflight and regulates vascular damage caused by simulated deep space radiation. In previous studies, we had identified miRNAs that are predicted to regulate rodent responses to spaceflight in low-Earth orbit. Here we have confirmed the expression of these proposed spaceflight associated miRNAs in rodents reacting to simulated spaceflight conditions (exposure to ionizing radiation combined with simulated microgravity) and in astronaut samples from the NASA Twins Study via direct quantification of miRNAs, miRNA sequencing, and inferring miRNA target levels based on single-cell RNA (scRNA-seq) and single-cell chromatin (scATAC-seq) sequencing data. To demonstrate the physiological relevance of key spaceflight associated miRNAs, we utilized antagomirs to inhibit their expression and successfully rescue simulated deep space radiation-mediated damage in human 3D vascular constructs.

Sherina Malkani↗

NASA NTRSDate not supplied

Spaceflight-Induced Changes in Microbial Virulence and the Impact to the Host Immune Response

Over the past 50 years, microorganisms have displayed unexpected responses relevant to infectious disease when grown in spaceflight and spaceflight analogues, including changes in final cell concentration, biofilm production, stress resistance, antibiotic sensitivity, gene expression, and virulence. •Seminal studies demonstrated that the foodborne pathogen, Salmonella enterica serovar Typhimurium, increased its virulence and pathogenesis-related characteristics in response to both spaceflight and spaceflight analogue culture. Since those experiments, alterations in the pathogenesis-related characteristics of other pathogens have been documented in response to growth in these environments4,5,6, and a recent study has demonstrated an increase in virulence of Serratia marcescens cultured during spaceflight7. However, our overall knowledge of which microorganisms will alter their virulence in response to spaceflight and spaceflight analogue culture remains very limited

C. M. Ott↗

NASA NTRSDate not supplied

Effects of Spaceflight Relevant Carbon Dioxide Levels on Pathogenesis Related Microbial Characteristics

BACKGROUND Multiple stressors in the spaceflight environment have the potential to alter microbial pathogenesis and virulence characteristics, including microgravity, radiation, and hostile/confined conditions. This combination of factors may lead to a stacking of risks, potentially creating unexpected increase in the risk of infectious disease. One understudied variable is the higher CO2 atmospheric concentration. The current Spaceflight Maximum Allowance Concentration (SMAC) for 24-hour average CO2 is 0.4% (3 mm Hg). These elevated ambient CO2 levels aboard the ISS could potentially influence the diversity and phenotypic responses of the resident microbial communities from both the spacecraft environment (air, surface, water) and crewmembers (gut, nasal, skin microbiomes). METHODS For these studies, we will evaluate the response of Staphylococcus aureus, Streptococcus pneumoniae and Enterobacter aerogenes, which are opportunistic pathogens that are of medical significance and have been or are likely to be found aboard spacecraft. These microorganisms will be cultured in both spaceflight analog and control conditions at CO2levels representing terrestrial atmospheric concentration of 0.04% (0.3 mmHg), ISS elevated concentration of 0.4% (3 mm Hg), and an unexpected elevated concentration of 1 % (7.6 mmHg) to represent a worst case scenario. DISCUSSION Overwhelming evidence from studies performed in food microbiology, marine biology and terrestrial environmental biology suggest altered gene expression, selective bacterial inhibition, increased growth and diversity, and increased antibiotic resistance of bacterial communities individually and in biofilm formation when exposed to increased levels of CO2. While many of these findings are based on levels of CO2 higher than would be found during spaceflight exploration missions, the potential for subtle changes in CO2 levels to exacerbate infectious disease risks warrants an evaluation of pathogen responses to spaceflight CO2 conditions. Our study will provide answers to spaceflight relevant atmospheric conditions, as described in the Risk of Adverse Health Effects Due to Host-Microorganism Interaction (GapMicro 103).

A A Medina-Colorado↗

NASA NTRS2022

Changes in Optic Nerve Head and Retinal Morphology During Spaceflight and Acute Fluid Shift Reversal

Importance: Countermeasures that reverse the headward fluid shift experienced in weightlessness have the potential to mitigate spaceflight-associated neuro-ocular syndrome. This study investigated whether use of the countermeasure lower-body negative pressure during spaceflight was associated with changes in ocular structure. Objective: To determine whether changes to the optic nerve head and retina during spaceflight can be mitigated by brief in-flight application of 25-mm Hg lower-body negative pressure. Design, Setting, and Participants: In the National Aeronautics and Space Administration’s “Fluid Shifts Study,” a prospective cohort study, optical coherence tomography scans of the optic nerve head and macula were obtained from US and international crew members before flight, in-flight, and up to 180 days after return to Earth. In-flight scans were obtained both under normal weightless conditions and 10 to 20 minutes into lower-body negative pressure exposure. Preflight and postflight data were collected in the seated, supine, and head-down tilt postures. Crew members completed 6- to 12-month missions that took place on the International Space Station. Data were analyzed from 2016 to 2021. Interventions or Exposures: Spaceflight and lower-body negative pressure. Main Outcomes and Measures: Changes in minimum rim width, optic cup volume, Bruch membrane opening height, peripapillary total retinal thickness, and macular thickness. Results: Mean (SD) flight duration for the 14 crew members (mean [SD] age, 45 [6] years; 11 male crew members [79%]) was 214 (72) days. Ocular changes on flight day 150, as compared with preflight seated, included an increase in minimum rim width (33.8 μm; 95% CI, 27.9-39.7 μm; P < .001), decrease in cup volume (0.038 mm^3; 95% CI, 0.030-0.046 mm^3; P < .001), posterior displacement of Bruch membrane opening (−9.0 μm; 95% CI, −15.7 to −2.2 μm; P = .009), and decrease in macular thickness (fovea to 500 μm, 5.1 μm; 95% CI, 3.5-6.8 μm; P < .001). Brief exposure to lower-body negative pressure did not affect these parameters. Conclusions and Relevance: Results of this cohort study suggest that peripapillary tissue thickening, decreased cup volume, and mild central macular thinning were associated with long-duration spaceflight. Acute exposure to 25-mm Hg lower-body negative pressure did not alter optic nerve head or retinal morphology, suggesting that longer durations of a fluid shift reversal may be needed to mitigate spaceflight-induced changes and/or other factors are involved.

Laura P. Pardon↗

NASA NTRSDate not supplied

Effects of Spaceflight Relevant Carbon Dioxide Levels on Pathogenesis Related Microbial Characteristics

Multiple stressors in the spaceflight environment, including microgravity and radiation, have the potential to alter microbial pathogenesis and virulence characteristics. Understanding how these and other factors may exacerbate the risk of infectious disease for astronauts is important to ensure the success of the mission. One understudied question in our assessment of infectious disease risk is the contribution carbon dioxide (CO2) at atmospheric concentrations higher than would be observed in terrestrial settings. Previous terrestrial studies have shown altered gene expression, selective bacterial inhibition, increased growth and diversity, and increased antibiotic resistance of bacterial communities individually and in biofilms when exposed to increased levels of CO2. While many of these findings are based on levels of CO2 higher than would be found during spaceflight exploration missions, the potential for subtle changes in CO2 levels to exacerbate infectious disease risks warrants an evaluation of pathogen responses to spaceflight CO2 conditions. To address this question, we are evaluating the effects of elevated atmospheric CO2 on microbial concentration, diversity, and pathogenesis-related characteristics using medically significant microorganisms cultured at CO2 levels representing terrestrial atmospheric concentration (≈0.04 %), ISS elevated concentration (0.4 %), and an unexpectedly elevated concentration (1 %) to represent a worst-case scenario. To determine if microbial responses to these CO2 concentrations may be exacerbated in response to the spaceflight environment, microorganisms are being cultured under static conditions and both spaceflight analogue and control conditions using the Rotating Wall Vessel (RWV) bioreactor (Synthecon, Houston, TX). For these studies, we will evaluate the response of Staphylococcus aureus, Streptococcus pneumoniae, and Enterobacter aerogenes, which are opportunistic bacterial pathogens that are of medical significance and have been or are likely to be found aboard human-inhabited spacecraft. Bacteria will be evaluated individually and together as a consortium. The following Specific Aims are be investigated: Aim 1. Characterize the growth, diversity, and pathogenesis-related stress responses of medically significant microorganisms grown under multiple CO2 concentrations under static growth in a liquid medium. Stress responses include acid stress, oxidative stress, and thermal stress. Aim 2. Characterize the growth, diversity, and pathogenesis-related stress responses of medically significant microorganisms grown under multiple CO2 concentrations in both spaceflight analogue and control conditions. Stress responses include acid stress, oxidative stress, and thermal stress.

S G Thornhill↗

NASA NTRSDate not supplied

Spaceflight-Induced Changes in Microbial Virulence and the Impact to the Host Immune Response

Many microbial pathogen shave repeatedly exhibited unexpected responses relevant to infectious disease when grown in microgravity and microgravity analogue environments, including changes in final cell concentration, biofilm production, stress resistance, antibiotic sensitivity, gene expression, host-pathogen interactions, and virulence. Notably, the classic foodborne pathogen Salmonella enterica serovar Typhimurium displayed increased virulence in animals when cultured in either the spaceflight analogue or true spaceflight environment. Recently, Serratia marcescens also was shown to increase virulence when cultured in the spaceflight environment. In parallel, astronaut studies have characterized a persistent spaceflight-induced dysregulation of the human immune system at multiple levels, which suggests an increased risk of infectious diseases. Moreover, astronauts have some degree of clinical infectious disease incidence. However, the contribution of the microgravity environment on host-pathogen interactions and potential for clinical disease remains understudied and poorly characterized. The goal of this study is to gain insight into the breadth of other medically significant microbial pathogens that may exhibit altered virulence and pathogenesis-related responses when cultured in space flight analogue conditions. Specifically, we are characterizing the effect of spaceflight analogue culture (Low Shear Modeled Microgravity/LSMMG) on microbial pathogenesis-related stress responses, in vitro host-pathogen interactions, gene expression, and virulence potential in animals using five important model bacterial pathogens, Salmonella enterica Enteritidis, Pseudomonas aeruginosa, Burkholderia cepacia, Streptococcus pneumoniae, and enterohemorrhagic Escherichia coli. Herein, we present data from one of these pathogens, the foodborne bacterium, S. enterica Enteritidis, which is closely related to S. enterica Typhimurium. Phenotypes evaluated included growth profiles, environmental stress responses(acid, oxidative, bile, and thermal stresses),and in vitro colonization of3-D biomimetic cultures of human intestinal tissue containing immune cells. Transcriptomic profiling and virulence studies are ongoing. We show that S. Enteritidis exhibited key alterations in pathogenic responses to LSMMG culture that suggest increased infection risk, including several responses which were different from those observed in the closely related pathovar S. Typhimurium. This information will provide critical mechanistic insight into the potential impact of microgravity on alterations in microbial virulence and associated infectious disease risk to crew health during spaceflight missions.

C M Ott↗

NASA NTRS2024

Spaceflight-Induced Changes in Microbial Virulence and the Impact to the Host Immune Response

C.M. Ott↗

NASA NTRS2023

Exploring the Complexities of Drug Formulation Selection, Storage, and Shelf-Life for Exploration Spaceflight

Medications have been a part of space travel dating back as far as the Apollo missions. Currently, medical kits aboard the ISS contain medications and supplies to help crew members cope with a variety of possible medical events. NASA reported that 1,867 medical events occurred from 1981 to 1998 on space shuttle flights, STS-1 to STS-89; 498 out of the 508 crewmembers on those flights reported experiencing a medical event other than space motion sickness. In 2000, the Institute of Medicine (IOM) convened a committee of experts, Committee on Creating a Vision for Space Medicine during Travel beyond Earth Orbit, to examine the issues surrounding astronaut health and safety for long duration space missions. The primary theme of the committee’s final report is that there is not enough known about the risks to human health during long-duration missions beyond Earth’s orbit and ways to effectively mitigate those risks in an environment of deep space. In 2014, the IOM convened the Committee on Ethics Principles and Guidelines for Health Standards for Long Duration and Exploration Spaceflights and released a report emphasizing the importance of prevention, mitigation, and treatment of major risks to human health during exploration spaceflight. NASA’s Human Research Program has organized five distinct categories of spaceflight hazards summarized by the acronym “RIDGE” (Space Radiation, Isolation and Confinement, Distance from Earth, Gravity fields, and Hostile/Closed Environments) that astronauts may encounter during exploration spaceflight. From those hazards, NASA further derived 30 of the most critical human health and performance risks, including limits to medical care resulting from pharmaceutical degradation. As we prepare for more distant exploration missions to Mars and beyond, risk management planning for astronaut healthcare should include the assembly of a medication formulary that is comprehensive enough to prevent or treat anticipated medical events, remains safe and chemically stable, and retains sufficient potency to last for the duration of the mission. The present editorial will summarize the current state of knowledge regarding innovative formulary optimization strategies, pharmaceutical stability assessment techniques, and storage and packaging solutions that could enhance drug safety and efficacy for future exploration spaceflight missions.

drug degradation risk assessment↗

NASA NTRS2018

Aging and Spaceflight: Catalase Targeted to Mitochondria Alters Skeletal Structure and Responses to Musculoskeletal Disuse

Microgravity and ionizing radiation in the spaceflight environment pose multiple challenges to homeostasis and may contribute to cellular stress. Effects may include increased generation of reactive oxygen species (ROS), DNA damage and repair error, cell cycle arrest, cell senescence or death. Our central hypothesis is that prolonged exposure to the spaceflight environment leads to excess production of ROS and oxidative damage, culminating in accelerated tissue degeneration which resembles aging. The main goal of this project is to determine the importance of cellular redox defense for physiological adaptations and tissue degeneration in the space environment. To accomplish this, we will use both wildtype (WT) mice and a well-established, genetically-engineered animal model (mCAT mice) which displays extended lifespan (Schriner et al. 2005). The animal model selected to test these ideas is engineered to quench ROS in mitochondria by targeted over-expression of the human catalase gene to the mitochondrial matrix. We showed previously that mCAT mice express the catalase transgene in skeletal tissues, bone forming osteoblasts, and bone resorbing osteoclasts. In addition, mCAT mice also display increased catalase activity in bone. Our findings revealed that exposure of adult, male, C57Bl/6J mice to simulated spaceflight (hindlimb unloading and gamma radiation) led to an increase in markers of oxidative damage (malondialdehyde, 4-hydroxynonenol) in skeletal tissue of WT mice but not mCAT mice. To extend our hypothesis to other, spaceflight-relevant tissues, we are performing a ground-based study simulating 30 days of spaceflight by hindlimb unloading to determine potential protective effects of mitochondrial catalase activity on aging of multiple tissues (cardiovascular, nervous and skeletal).

transgenic mice↗

NASA NTRS1992

Spaceflight and growth effects on muscle fibers in the rhesus monkey

The effect of a 14-day spaceflight onboard Cosmos 2044 on selected morphological and metabolic properties of single muscle fibers was investigated in a nonhuman primate, Macaca mulatta. It is concluded that the 14-day spaceflight had little impact on fiber size in the soleus (S) and medial gastrocnemius (MG) muscles, whereas it appeared to be a slight decrease in sized in the tibialis anterior (TA). The mean fiber size in the postflight biopsies increased relative to preflight values. The mean fiber succinate dehydrogenase activity was found to decrease in the MG, whereas there was no apparent effect of spaceflight on the s and ta muscles. The differences in response of the S, MG, and TA to spaceflight in monkeys vs rats may be related to a species responsiveness to spaceflight, the manner in which the animals were restrained, and/or the possibility that the ankle musculature was able to function against a load while in space.

Bodine-Fowler, Sue C.↗

NASA NTRS1991

Cardiovascular adaptation to spaceflight

Data are presented on the rate of adaptation of the human cardiovascular system to conditions of spaceflight, with particular attention given to data obtained during spaceflight in the U.S. Space Shuttle Program. It is pointed out that many of the cardiovascular changes that occurred during spaceflights that lasted from 2 to 11 days can be traced directly to changes in the body fluid volume. The beneficial effects of a fluid loading countermeasure (oral rehydration) and of the supine body position on the heart rate during the spaceflight are demonstrated. It is noted that, after hours or a few days of spaceflight, a state of adaptation is reached, in which the subject is well adapted and appropriately hydrated for the weightless environment. However, the return to the normal gravity of the earth leaves the individual especially sensitive to orthostatic stress.

Charles, John B.↗

NASA NTRS1994

Comparison of the Physiology of the Spaceflight and Hindlimb Suspended Rat

The suspended rat has been used extensively as a simulation of the spaceflight animal. In suspension, hindlimbs are unloaded from the acceleration of gravity, much as they are in spaceflight. Comparisons of data from spaceflight (microgravity) and suspended (1G) rats have suggested that suspension my be an appropriate model, but no direct comparisons had been made between the spaceflight and suspended rat. Cosmos 2044 afforded the first opportunity to directly compare the effects of hindlimb suspension (HS) and spaceflight (SF) on a broad range of physiological and histological parameters. This paper reports on the comparison of skelton, skeletal muscle, heart, neural, pulmonary, kidney, liver, intestine, blood plasma, immune function, red blood cells, and endocrine and reproductive functions and systems.

Grindeland, R. E.↗

NASA NTRS1999

Effects of Spaceflight on Bone: The Rat as an Animal Model for Human Bone Loss

The loss of weight bearing during spaceflight results in osteopenia in humans. Decrements in bone mineral reach 3-10% after as little as 75-184 days in space. Loss of bone mineral during flight decreases bone strength and increases fracture risk. The mechanisms responsible for, and the factors contributing to, the changes in bone induced by spaceflight are poorly understood. The rat has been widely used as an animal model for human bone loss during spaceflight. Despite its potential usefulness, the results of bone studies performed in the rat in space have been inconsistent. In some flights bone formation is decreased and cancellous bone volume reduced, while in others no significant changes in bone occur. In June of 1996 Drs. T. Wronski, S. Miller and myself participated in a flight experiment (STS 78) to examine the effects of glucocorticoids on bone during weightlessness. Technically the 17 day flight experiment was flawless. The results, however, were surprising. Cancellous bone volume and osteoblast surface in the proximal tibial metaphysis were the same in flight and ground-based control rats. Normal levels of cancellous bone mass and bone formation were also detected in the lumbar vertebrae and femoral neck of flight rats. Furthermore, periosteal bone formation rate was found to be identical in flight and ground-based control rats. Spaceflight had little or no effect on bone metabolism! These results prompted us to carefully review the changes in bone observed in, and the flight conditions of previous spaceflight missions.

Halloran, B.↗

NASA NTRS2001

Investigation of the Influence of Microgravity on Transport Mechanisms in a Virtual Spaceflight Chamber: A Ground-Based Program

The IML-1 Spaceflight produced over 1000 holograms of a well-defined particle field in the low g Spacelab environment; each containing as much as 1000 megabytes of information. This project took advantage of these data and the concept of holographic "virtual" spaceflight to advance the understanding of convection in the space shuttle environment, g-jitter effects on crystal growth, and complex transport phenomena in low Reynolds number flows. The first objective of the proposed work was to advance the understanding of microgravity effects on crystal growth. This objective was achieved through the use of existing holographic data recorded during the IML-1 Spaceflight. The second objective was to design a spaceflight experiment that exploits the "virtual space chamber concept" in which holograms of space chambers can provide a virtual access to space. This led to a flight definition project, which is now underway under a separate contract known as SHIVA, Spaceflight Holography Investigation in a Virtual Apparatus.

Trolinger, James D.↗

NASA NTRS2001

Looking Backward, Looking Forward: Forty Years of US Human Spaceflight Symposium

This symposium reflects on forty years of U.S. Human Spaceflight, its role over the next four decades and beyond. The topics include: 1) Perspectives on the Past Forty Years of Human Spaceflight; 2) The Experience of Spaceflight; 3) Perspectives on the Next Forty Years of Human Spaceflight; and 4) The International Space Station and the Future of Human Spaceflight.

Garber, Stephen J.↗