npj Microgravity最新文献

Microgravity offers a unique platform for understanding how physical forces influence the fate and function of stem cells. This review integrates recent findings on genomic, epigenetic, and mechanotransductive responses of diverse stem cell types under actual and simulated microgravity conditions. It uniquely relates these biological insights with space-based biomanufacturing, translational applications, and ethical frameworks, highlighting how space-enabled stem cell research advances regenerative medicine both in orbit and on Earth.

Exposure to microgravity results in transient sensorimotor performance declines when crewmembers return to Earth, likely due to sensory re-weighting. This poses performance risks following gravitational transitions, such as arriving on the Moon or Mars. Here, we examined whether sensory brain network segregation (how independently a given network functions) in astronauts prior to an International Space Station mission would predict balance post-flight. Intraclass correlation analysis showed high test-retest reliability for all sensory network segregation measures. Indices of the Parietal Operculum 2 network (OP2) segregation pre-flight significantly predicted balance performance. Specifically, greater segregation predicted poorer balance on day one following return to Earth (Left OP2), better balance four days post-flight (Left and Right OP2) and greater balance improvements from one to four days post-flight. Results suggest that OP2 segregation may index plasticity of sensory weighting processes; that is, the degree of vestibular input down-weighting measured initially post-flight and extent of recovery over subsequent four days.

Orthostatic intolerance (OI) remains a post-flight challenge for astronauts. As part of the ESA/CNES BRACE bed rest study, we tested, in ambulatory participants, a combined individualized cycling exercise and artificial gravity (AG) training procedure as a multi-system OI countermeasure. The training limits of cycling intensity and AG exposure were based on individual V̇O2peak and presyncopal AG level. In a randomized crossover design, heart rate (HR) and blood pressure responses were assessed during cycling with or without AG exposure. Our results demonstrated cardiovascular stimuli (i.e., higher HR and blood pressure) during cycling with AG exposure. Greater maximum HR responses were observed in men with AG exposure. This novel individualized exercise and orthostatic training protocol was successful in providing each participant with equally strenuous cardiovascular stimuli close to their tolerance limits regardless of individual and sex differences.

Cardiovascular (CV) deconditioning is a consequence of spaceflight, characterized by functional and structural changes in the heart and blood vessels due to prolonged exposure to microgravity. These adaptations lead to a noticeable reduction in exercise capacity, particularly evident in alterations of maximum aerobic power (VO₂ max [mL/kg/min]). This work explored the hypothesis that microgravity-induced CV deconditioning could be anticipated through information derived from a non-exercise longitudinal 24-h Holter ECG recording, thereby offering a means for its regular monitoring in space. Pooled data acquired at baseline and at the last day of six Head-Down Tilt bed rest campaigns of different duration were utilized to test this hypothesis. Machine Learning models were developed using multiple features to predict VO₂ max after deconditioning. Obtained results showed good prediction accuracy (RMSE < 5 mL/kg/min) demonstrating the potential of this approach to identify VO₂ max deterioration during bed rest, with possible applications in real world space environments and clinical settings.

Natural killer (NK) cells play an important role in antitumor and viral resistance. However, the mechanism of impaired NK cell function in microgravity remains unclear. Cholesterol metabolism, a new research hotspot, plays a critical role in NK cells function. This study found that simulated microgravity downregulate NK cell membrane cholesterol levels by disrupting cholesterol biosynthesis and transport to the membrane, leading to the obstruction of activated immune synapse formation, which inhibit the release of NK cell cytotoxic particles and ultimately decreasing NK cell immune function. Most importantly, this study identified a new target for regulating NK cell function, LEPR (leptin receptor). LEPR affected NK cell membrane cholesterol levels by influencing the CAMKK-SREBP1-HMGCR cholesterol endogenous synthesis pathway and regulating the expression of NPC1 and NPC2 genes, which ultimately influencing NK cell cytotoxic function. The study is significant for understanding the mechanism of NK cell activity in microgravity and offers new targets for clinical immunotherapy of NK cells.

Human spaceflight is advancing toward sustainable exploration through initiatives like NASA's Artemis program, aiming for a lunar outpost and eventual Mars mission. Astronauts face hazards including altered gravity, isolation, and cosmic radiation, linked to over thirty health risks. This review, reflecting ESA community expertise, outlines how understanding the space exposome-integrome interaction can improve risk stratification, guide personalized countermeasures, and address knowledge gaps essential for safe deep-space exploration.

Biomedical research during spaceflight and simulation studies reveals significant changes in biochemical and cellular pathways relevant to understanding diseases on Earth. While adult health has been the historical focus of aerospace medicine, applications for children's health remain unexplored and are becoming more paramount as civilian access to space increases. We discuss biological and physiological changes in spaceflight that may be relevant to pediatric diseases. We also explore nutritional approaches for pediatric conditions, which may also benefit astronaut health.

Contemporary plans to establish human habitation on the Earth's Moon have increased interest in the ability of humans to establish extraterrestrial pregnancies. There is a lack of data to identify if humans could safely reproduce away from the Earth, and even less guidance with regard to whether we should attempt to do so. This work was developed to stimulate investigation into the likely biological and ethical challenges facing the establishment and maintenance of a healthy human extraterrestrial pregnancy.

Spaceflight Standard Measures is an integrated research study designed to characterize how spaceflight affects the health and performance of astronauts. Standardizing the research methods allows for robust monitoring of individuals and allows comparison between crewmembers of different missions of various durations. This manuscript reviews the objectives of the Spaceflight Standard Measures project, and details how each disciplinary component is used to monitor spaceflight-induced human risks. It also covers the timeline of data collection, the methods used to analyze the data, and the process for requesting access to the data. With the impending return to lunar operations and exploration of deep space, an urgent need exists for high-quality, multidisciplinary investigations to inform programmatic and operational decisions. The Spaceflight Standard Measures model provides a standardized, flexible research approach, fostering collaboration across agencies to create a strong evidence base that can be used to safely advance human spaceflight into multiplanetary exploration.

Microgravity exposure induces cardiac deconditioning, primarily due to hypovolemia and inactivity. Animal models suggest microgravity may cause left ventricular (LV) papillary muscle atrophy, but this has not been studied in humans. This study used MRI to assess LV papillary muscle mass and LV morphology and function in nine male cosmonauts before and 6 ± 2 days after long-duration spaceflight (247 ± 90 days). Spaceflight did not affect LV volumes, ejection fraction, and strain parameters, but increased heart rate (P < 0.001) and cardiac output (P = 0.03). LV papillary muscle mass decreased by 14% (P = 0.017), while LV mass tended to increase (P = 0.083), mitral annular diameter increased (P = 0.004) without mitral leakage, and LV sphericity increased (P = 0.02). These findings suggest LV adapts to space with geometric changes, but microgravity-induced papillary muscle atrophy requires further study for long-term implications.