Search Results (50)

Background: With renewed interest in long-duration space missions, there is growing exploration into synthetic torpor as a countermeasure to mitigate physiological stressors. Sedative agents, particularly those used in clinical anesthesia, have been proposed to replicate aspects of natural torpor, including reduced metabolic rate, core temperature, and brain activity. Objectives: This systematic review aims to evaluate the potential of sedative agents to induce torpor-like states suitable for extended spaceflight. The review specifically investigates their pharmacokinetics, pharmacodynamics, and performance under space-related stressors such as microgravity and ionizing radiation. Methods: We conducted a comprehensive search across multiple databases (e.g., PubMed, Scopus, Web of Science) for studies published from 1952 to 2024. Eligible studies included experimental, preclinical, and clinical investigations examining sedative agents (especially inhalation anesthetics) in the context of metabolic suppression or space-relevant conditions. Screening, selection, and data extraction followed PRISMA guidelines. Results: Out of the screened records, 141 studies met the inclusion criteria. These were thematically grouped into seven categories, including torpor physiology, anesthetic uptake, metabolism, and inhalation anesthetics. Sedative agents showed variable success in inducing torpor-like states, with inhalation anesthetics demonstrating promising metabolic effects. However, concerns remain regarding delivery methods, safety, rewarming, and the unknown effects of prolonged use in space environments. Conclusions: Sedative agents, particularly volatile anesthetics, hold potential as tools for inducing synthetic torpor in space. Nevertheless, significant knowledge gaps and technical challenges persist. Further targeted research is required to optimize these agents for safe, controlled use in spaceflight settings. Full article

Human space exploration presents an unparalleled opportunity to study life in extreme environments—but it also exposes astronauts to physiological stressors that jeopardize key systems like vision. Corneal health, essential for maintaining precise visual acuity, is threatened by microgravity-induced fluid shifts, cosmic radiation, and the confined nature of spacecraft living environments. These conditions elevate the risk of corneal abrasions, infections, and structural damage. In addition, Spaceflight-Associated Neuro-Ocular Syndrome (SANS)—while primarily affecting the posterior segment—has also been potentially linked to anterior segment alterations such as corneal edema and tear film instability. This review examines these ocular challenges and assesses current mitigation strategies. Traditional approaches, such as terrestrial eye banking and corneal transplantation, are impractical for spaceflight due to the limited viability of preserved tissues, surgical complexities, anesthetic risks, infection potential, and logistical constraints. The paper explores emerging technologies like 3D bioprinting and stem cell-based tissue engineering, which offer promising solutions by enabling the on-demand production of personalized corneal constructs. Complementary advancements, including adaptive protective eyewear, bioengineered tear substitutes, telemedicine, and AI-driven diagnostic tools, also show potential in autonomously managing ocular health during long-duration missions. By addressing the complex interplay of environmental stressors and biological vulnerabilities, these innovations not only safeguard astronaut vision and mission performance but also catalyze new pathways for regenerative medicine on Earth. The evolution of space-based ophthalmic care underscores the dual impact of space medicine investments across planetary exploration and terrestrial health systems. Full article

With the continued exploration of the universe, there is an increasingly urgent need to address the health challenges arising from spaceflight. In space, astronauts are exposed to radiation, confinement and isolation, circadian rhythm dysregulation, and microgravity conditions that are different from those on Earth. These risk factors jeopardize astronauts’ health, thus affecting the quality of space missions. Among these factors, gravitational changes influence the balance between oxidation and antioxidants, stimulating the production of reactive oxygen species (ROS), finally leading to oxidative stress (OS). OS leads to oxidative damage of biomolecules such as lipids, proteins, and DNA, which causes the development of various diseases. The occurrence of OS is increased in microgravity and affects multiple systems, including the musculoskeletal, cardiovascular, nervous, and immune systems. In this review, we discuss the mechanisms of OS, the physiological effects on different systems caused by OS in microgravity environment, and potential treatments for OS. Finally, treatment strategies for oxidative stress in microgravity are summarized, providing some promising approaches for protecting the health of astronauts in future space exploration. Full article

Space exploration has progressed from contemporary discoveries to current endeavors, such as space tourism and Mars missions. As human activity in space accelerates, understanding the physiological effects of microgravity on the human body is becoming increasingly critical. This study analyzes transcriptomic data from human cell lines exposed to microgravity, investigates its effects on gene expression, and identifies potential therapeutic interventions for health challenges posed by spaceflight. Our analysis identified five under-expressed genes (DNPH1, EXOSC5, L3MBTL2, LGALS3BP, SPRYD4) and six over-expressed genes (CSGALNACT2, CSNK2A2, HIPK1, MBNL2, PHF21A, RAP1A), all of which exhibited distinct expression patterns in response to microgravity. Enrichment analysis highlighted significant biological functions influenced by these conditions, while in silico drug repurposing identified potential modulators that could counteract these changes. This study introduces a novel approach to addressing health challenges during space missions by repurposing existing drugs and identifies specific genes and pathways as potential biomarkers for microgravity effects on human health. Our findings represent the first systematic effort to repurpose drugs for spaceflight, establishing a foundation for the development of targeted therapies for astronauts. Future research should aim to validate these findings in authentic space environments and explore broader biological impacts. Full article

In recent years, the increasing number of long-duration space missions has prompted the scientific community to undertake a more comprehensive examination of the impact of microgravity on the human body during spaceflight. This review aims to assess the current knowledge regarding the consequences of exposure to an extreme environment, like microgravity, on the human body, focusing on the role of heat-shock proteins (HSPs). Previous studies have demonstrated that long-term exposure to microgravity during spaceflight can cause various changes in the human body, such as muscle atrophy, changes in muscle fiber composition, cardiovascular function, bone density, and even immune system functions. It has been postulated that heat-shock proteins (HSPs) may play a role in mitigating the harmful effects of microgravity-induced stress. According to past studies, heat-shock proteins (HSPs) are upregulated under simulated microgravity conditions. This upregulation assists in the maintenance of the proper folding and function of other proteins during stressful conditions, thereby safeguarding the physiological systems of organisms from the detrimental effects of microgravity. HSPs could also be used as biomarkers to assess the level of cellular stress in tissues and cells exposed to microgravity. Therefore, modulation of HSPs by drugs and genetic or environmental techniques could prove to be a potential therapeutic strategy to reduce the negative physiological consequences of long-duration spaceflight in astronauts. Full article

The space environment can affect the function of all physiological systems, including the properties of cell membranes. Our goal in this study was to explore the effect of simulated microgravity (SMG) on the cellular uptake of small molecules based on reported microgravity-induced changes in membrane properties. SMG was applied to cultured cells using a random-positioning machine for up to three hours. We assessed the cellular accumulation of compounds representing substrates of uptake and efflux transporters, and of compounds not shown to be transported by membrane carriers. Exposure to SMG led to an increase of up to 60% (p < 0.01) in the cellular uptake of efflux transporter substrates, whereas a glucose transporter substrate showed a decrease of 20% (p < 0.05). The uptake of the cathepsin activity-based probe GB123 (MW, 1198 g/mol) was also enhanced (1.3-fold, p < 0.05). Cellular emission of molecules larger than ~3000 g/mol was reduced by up to 50% in SMG (p < 0.05). Our findings suggest that short-term exposure to SMG could differentially affect drug distribution across membranes. Longer exposure to microgravity, e.g., during spaceflight, may have distinct effects on the cellular uptake of small molecules. Full article

With increasing space exploration, there is a rising need to evaluate the impact of spaceflight on astronauts’ health, including the effects of space-associated hazards such as microgravity. Astronauts’ reports of experienced symptoms upon spaceflight include a notable prevalence of dry eye disease (DED). Hence, there is a pressing need to understand the pathogenesis and mechanism behind space-associated DED onset, which will subsequently guide the development of necessary therapies to reduce dry eye symptoms among astronauts. One critical effect of spaceflight includes alterations to the gut microbiome. On Earth, the prior literature has established the presence of an ocular surface–gut axis and the potential role of gut dysbiosis in DED onset. Meanwhile, the literature about astronauts’ health underscores the presence of space-associated gut microbiome composition alterations and the presence of DED separately. Therefore, in this opinion article, we review and present the current literature regarding the ocular surface–gut axis on Earth and regarding potential translations to spaceflight. We present the view that, based on the existing literature, the ocular surface–gut axis may be a critical mechanism for the pathogenesis of DED in space, and this axis needs to be further explored in the context of identifying ways to reduce astronauts’ experiences of DED during spaceflight. Full article

Microgravity in spaceflight produces headward fluid shifts which probably contribute to Spaceflight-Associated Neuro-Ocular Syndrome (SANS). Developing new methods to mitigate these shifts is crucial for preventing SANS. One possible strategy is the use of self-generated lower body negative pressure (LBNP). This study evaluates biological or physiological effects induced by bed rest to simulate adaptations to microgravity. Participants were tested during powered LBNP and dynamic self-generated (SELF) LBNP at 25 mmHg for 15 min. The results were compared to the physiologic responses observed in seated upright and supine positions without LBNP, which served as controls for normal gravitational effects on fluid dynamics. Eleven participants’ (five male, six female) heart rates, blood pressures, and cross-sectional areas (CSA) of left and right internal jugular veins (IJV) were monitored. Self-generated LBNP, which requires mild to moderate physical activity, significantly elevated heart rate and blood pressure (p < 0.01). Self-generated LBNP also significantly reduced right IJV CSA compared to supine position (p = 0.005), though changes on the left side were not significant (p = 0.365). While the effects of SELF and traditional LBNP on IJV CSA were largely similar, traditional LBNP significantly reduced IJV CSA on both sides. Given its low mass, volume, and power requirements, SELF LBNP is a promising countermeasure against SANS. Results from this study warrant longer-term studies of SELF LBNP under simulated spaceflight conditions. Full article

Ocular health is currently a major concern for astronauts on current and future long-duration spaceflight missions. Spaceflight-associated neuro-ocular syndrome (SANS) is a collection of ophthalmic and neurologic findings that is one potential physiologic barrier to interplanetary spaceflight. Since its initial report in 2011, our understanding of SANS has advanced considerably, with a primary focus on posterior ocular imaging including fundus photography and optical coherence tomography. However, there may be changes to the anterior segment that have not been identified. Additional concerns to ocular health in space include corneal damage and radiation-induced cataract formation. Given these concerns, precision anterior segment imaging of the eye would be a valuable addition to future long-duration spaceflights. The purpose of this paper is to review ultrasound biomicroscopy (UBM) and its potential as a noninvasive, efficient imaging modality for spaceflight. The analysis of UBM for spaceflight is not well defined in the literature, and such technology may help to provide further insights into the overall anatomical changes in the eye in microgravity. Full article

Prolonged inactivity and disuse conditions, such as those experienced during spaceflight and prolonged bedrest, are frequently accompanied by detrimental effects on the motor system, including skeletal muscle atrophy and bone loss, which greatly increase the risk of osteoporosis and fractures. Moreover, the decrease in glucose and lipid utilization in skeletal muscles, a consequence of muscle atrophy, also contributes to the development of metabolic syndrome. Clarifying the mechanisms involved in disuse-induced musculoskeletal deterioration is important, providing therapeutic targets and a scientific foundation for the treatment of musculoskeletal disorders under disuse conditions. Skeletal muscle, as a powerful endocrine organ, participates in the regulation of physiological and biochemical functions of local or distal tissues and organs, including itself, in endocrine, autocrine, or paracrine manners. As a motor organ adjacent to muscle, bone tissue exhibits a relative lag in degenerative changes compared to skeletal muscle under disuse conditions. Based on this phenomenon, roles and mechanisms involved in the communication between skeletal muscle and bone, especially from muscle to bone, under disuse conditions have attracted widespread attention. In this review, we summarize the roles and regulatory mechanisms of muscle-derived myokines and extracellular vesicles (EVs) in the occurrence of muscle atrophy and bone loss under disuse conditions, as well as discuss future perspectives based on existing research. Full article

(1) Background: Starting in 1993, the sociomapping method was used in the Czech Army to map communication. After initial pilot tests in military aviation, where we verified the reliability and validity of the basic subjective scales (for example, by correlations with physiological data), this method was utilized for communication mapping in the HUBES (Human Behavior in Extended Spaceflight) experiment conducted between 1994 and 1995, and since then has been repeatedly used in experiments simulating long-term space flights. (2) Methods: In this article, we summarize the key findings obtained through sociomapping in eight space experiments with crews including women, conducted between 2015 and 2023, including five experiments at the Mars Desert Research Station (MDRS) and in three stages of the SIRIUS project (Scientific International Research in Unique Terrestrial Station). (3) Results: The median test-retest correlation for both the frequency and quality of communication was 0.64, ranging widely from −0.74 to 1. The quantity and quality of communication showed a moderately strong correlation (0.40). Control charts demonstrated diverse developmental trends in crew communication across the experiments. Sociomapping allowed for more detailed visualization of the structure and dynamics of communication throughout the missions, as well as the detection of subgrouping and isolation of individuals in the crews. (4) Conclusions: The experiments showed that scaled assessments of mutual communication in terms of both quantity (frequency) and quality are a reliable and valid tool that enables the capture of significant one-time fluctuations and/or long-term trends. The experiments highlighted the possibility of increased risk of significant fluctuations and gradual deterioration of communication in the second half of the mission, which, however, does not have to be the rule, especially in shorter isolations. Continuous monitoring of communication through simple rating scales allows for timely intervention and stabilization of communication. Full article

A method was previously developed to identify participant-specific parameters in a model of trabecular bone adaptation from longitudinal computed tomography (CT) imaging. In this study, we use these numerical methods to estimate changes in astronaut bone health during the distinct phases of spaceflight and recovery on Earth. Astronauts (N = 16) received high-resolution peripheral quantitative CT (HR-pQCT) scans of their distal tibia prior to launch (L), upon their return from an approximately six-month stay on the international space station (R+0), and after six (R+6) and 12 (R+12) months of recovery. To model trabecular bone adaptation, we determined participant-specific parameters at each time interval and estimated their bone structure at R+0, R+6, and R+12. To assess the fit of our model to this population, we compared static and dynamic bone morphometry as well as the Dice coefficient and symmetric distance at each measurement. In general, modeled and observed static morphometry were highly correlated (R²> 0.94) and statistically different (p < 0.0001) but with errors close to HR-pQCT precision limits. Dynamic morphometry, which captures rates of bone adaptation, was poorly estimated by our model (p < 0.0001). The Dice coefficient and symmetric distance indicated a reasonable local fit between observed and predicted bone volumes. This work applies a general and versatile computational framework to test bone adaptation models. Future work can explore and test increasingly sophisticated models (e.g., those including load or physiological factors) on a participant-specific basis. Full article

Background: Understanding and countering the well-established negative health consequences of spaceflight remains a primary challenge preventing safe deep space exploration. Targeted/personalized therapeutics are at the forefront of space medicine strategies, and cross-species molecular signatures now define the ‘typical’ spaceflight response. However, a lack of direct genotype–phenotype associations currently limits the robustness and, therefore, the therapeutic utility of putative mechanisms underpinning pathological changes in flight. Methods: We employed the worm Caenorhabditis elegans as a validated model of space biology, combined with ‘NemaFlex-S’ microfluidic devices for assessing animal strength production as one of the most reproducible physiological responses to spaceflight. Wild-type and dys-1 (BZ33) strains (a Duchenne muscular dystrophy (DMD) model for comparing predisposed muscle weak animals) were cultured on the International Space Station in chemically defined media before loading second-generation gravid adults into NemaFlex-S devices to assess individual animal strength. These same cultures were then frozen on orbit before returning to Earth for next-generation sequencing transcriptomic analysis. Results: Neuromuscular strength was lower in flight versus ground controls (16.6% decline, p < 0.05), with dys-1 significantly more (23% less strength, p < 0.01) affected than wild types. The transcriptional gene ontology signatures characterizing both strains of weaker animals in flight strongly corroborate previous results across species, enriched for upregulated stress response pathways and downregulated mitochondrial and cytoskeletal processes. Functional gene cluster analysis extended this to implicate decreased neuronal function, including abnormal calcium handling and acetylcholine signaling, in space-induced strength declines under the predicted control of UNC-89 and DAF-19 transcription factors. Finally, gene modules specifically altered in dys-1 animals in flight again cluster to neuronal/neuromuscular pathways, suggesting strength loss in DMD comprises a strong neuronal component that predisposes these animals to exacerbated strength loss in space. Conclusions: Highly reproducible gene signatures are strongly associated with space-induced neuromuscular strength loss across species and neuronal changes in calcium/acetylcholine signaling require further study. These results promote targeted medical efforts towards and provide an in vivo model for safely sending animals and people into deep space in the near future. Full article

Microgravity introduces diverse pathological and various physiological changes to the human body, including intraocular pressure. Astronauts may develop a constellation of symptoms and signs including optic disc edema, choroidal folds, and a hyperopic shift from the flattening of the globe. These ocular findings have been collectively termed spaceflight-associated neuro-ocular syndrome (SANS). SANS is a condition that is unique to long-duration spaceflight. The precise pathogenesis of SANS remains ill-defined, but several hypotheses have been proposed that may be influenced by intraocular pressure. Countermeasures for SANS research also include techniques that impact intraocular pressure. In this article, we discuss intraocular pressure during spaceflight, the translaminar pressure gradient, SANS and potential SANS countermeasures, and the potential for glaucomatous damage during spaceflight. Full article

Space colonization represents the most insidious challenge for mankind, as numerous obstacles affect the success of space missions. Specifically, the absence of gravitational forces leads to systemic physiological alterations, with particular emphasis on the musculoskeletal system. Indeed, astronauts exposed to spaceflight are known to report a significant impairment of bone microarchitecture and muscle mass, conditions clinically defined as osteoporosis and sarcopenia. In this context, space medicine assumes a crucial position, as the development of strategies to prevent and/or counteract weightlessness-induced alterations appears to be necessary. Furthermore, the opportunity to study the biological effects induced by weightlessness could provide valuable information regarding adaptations to spaceflight and suggest potential treatments that can preserve musculoskeletal health under microgravity conditions. Noteworthy, improving knowledge about the latest scientific findings in this field of research is crucial, as is thoroughly investigating the mechanisms underlying biological adaptations to microgravity and searching for innovative solutions to counter spaceflight-induced damage. Therefore, this narrative study review, performed using the MEDLINE and Google Scholar databases, aims to summarize the most recent evidence regarding the effects of real and simulated microgravity on the musculoskeletal system and to discuss the effectiveness of the main defence strategies used in both real and experimental settings. Full article