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Richmond SB, Seidler RD, Iliff JJ, Schwartz DL, Luther M, Silbert LC, Wood SJ, Bloomberg JJ, Mulder E, Lee JK, De Luca A, Piantino J. Dynamic changes in perivascular space morphology predict signs of spaceflight-associated neuro-ocular syndrome in bed rest. NPJ Microgravity 2024; 10:24. [PMID: 38429289 PMCID: PMC10907584 DOI: 10.1038/s41526-024-00368-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 02/15/2024] [Indexed: 03/03/2024] Open
Abstract
During long-duration spaceflight, astronauts experience headward fluid shifts and expansion of the cerebral perivascular spaces (PVS). A major limitation to our understanding of the changes in brain structure and physiology induced by spaceflight stems from the logistical difficulties of studying astronauts. The current study aimed to determine whether PVS changes also occur on Earth with the spaceflight analog head-down tilt bed rest (HDBR). We examined how the number and morphology of magnetic resonance imaging-visible PVS (MV-PVS) are affected by HDBR with and without elevated carbon dioxide (CO2). These environments mimic the headward fluid shifts, body unloading, and elevated CO2 observed aboard the International Space Station. Additionally, we sought to understand how changes in MV-PVS are associated with signs of Spaceflight Associated Neuro-ocular Syndrome (SANS), ocular structural alterations that can occur with spaceflight. Participants were separated into two bed rest campaigns: HDBR (60 days) and HDBR + CO2 (30 days with elevated ambient CO2). Both groups completed multiple magnetic resonance image acquisitions before, during, and post-bed rest. We found that at the group level, neither spaceflight analog affected MV-PVS quantity or morphology. However, when taking into account SANS status, persons exhibiting signs of SANS showed little or no MV-PVS changes, whereas their No-SANS counterparts showed MV-PVS morphological changes during the HDBR + CO2 campaign. These findings highlight spaceflight analogs as models for inducing changes in MV-PVS and implicate MV-PVS dynamic compliance as a mechanism underlying SANS. These findings may lead to countermeasures to mitigate health risks associated with human spaceflight.
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Affiliation(s)
- Sutton B Richmond
- Department of Applied Physiology and Kinesiology, University of Florida, 1864, Stadium Rd., Gainesville, FL, USA
| | - Rachael D Seidler
- Department of Applied Physiology and Kinesiology, University of Florida, 1864, Stadium Rd., Gainesville, FL, USA
- Norman Fixel Institute for Neurological Diseases, University of Florida, Gainesville, FL, USA
| | - Jeffrey J Iliff
- Department of Psychiatry and Behavioral Sciences, University of Washington School of Medicine, Seattle, WA, USA
- Department of Neurology, University of Washington School of Medicine, Seattle, WA, USA
- VISN 20 Mental Illness Research, Education and Clinical Center (MIRECC), VA Puget Sound Health Care System, Seattle, WA, USA
| | - Daniel L Schwartz
- Layton-NIA Oregon Aging and Alzheimer's Disease Research Center, Department of Neurology, Oregon Health & Science University, Portland, OR, USA
- Advanced Imaging Research Center, Oregon Health & Science University, Portland, OR, USA
| | - Madison Luther
- Department of Pediatrics, Division of Child Neurology, Doernbecher Children's Hospital, Oregon Health and Science University, Portland, OR, USA
| | - Lisa C Silbert
- Layton-NIA Oregon Aging and Alzheimer's Disease Research Center, Department of Neurology, Oregon Health & Science University, Portland, OR, USA
- Veteran's Affairs Portland Health Care System, Neurology, Portland, OR, USA
| | | | | | | | - Jessica K Lee
- Department of Applied Physiology and Kinesiology, University of Florida, 1864, Stadium Rd., Gainesville, FL, USA
- German Aerospace Center (DLR), Cologne, Germany
| | - Alberto De Luca
- Department of Radiology, University Medical Center Utrecht, Utrecht, Netherlands
| | - Juan Piantino
- Department of Pediatrics, Division of Child Neurology, Doernbecher Children's Hospital, Oregon Health and Science University, Portland, OR, USA.
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Homo sapiens—A Species Not Designed for Space Flight: Health Risks in Low Earth Orbit and Beyond, Including Potential Risks When Traveling beyond the Geomagnetic Field of Earth. Life (Basel) 2023; 13:life13030757. [PMID: 36983912 PMCID: PMC10051707 DOI: 10.3390/life13030757] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2023] [Revised: 03/03/2023] [Accepted: 03/08/2023] [Indexed: 03/18/2023] Open
Abstract
Homo sapiens and their predecessors evolved in the context of the boundary conditions of Earth, including a 1 g gravity and a geomagnetic field (GMF). These variables, plus others, led to complex organisms that evolved under a defined set of conditions and define how humans will respond to space flight, a circumstance that could not have been anticipated by evolution. Over the past ~60 years, space flight and living in low Earth orbit (LEO) have revealed that astronauts are impacted to varying degrees by such new environments. In addition, it has been noted that astronauts are quite heterogeneous in their response patterns, indicating that such variation is either silent if one remained on Earth, or the heterogeneity unknowingly contributes to disease development during aging or in response to insults. With the planned mission to deep space, humans will now be exposed to further risks from radiation when traveling beyond the influence of the GMF, as well as other potential risks that are associated with the actual loss of the GMF on the astronauts, their microbiomes, and growing food sources. Experimental studies with model systems have revealed that hypogravity conditions can influence a variety biological and physiological systems, and thus the loss of the GMF may have unanticipated consequences to astronauts’ systems, such as those that are electrical in nature (i.e., the cardiovascular system and central neural systems). As astronauts have been shown to be heterogeneous in their responses to LEO, they may require personalized countermeasures, while others may not be good candidates for deep-space missions if effective countermeasures cannot be developed for long-duration missions. This review will discuss several of the physiological and neural systems that are affected and how the emerging variables may influence astronaut health and functioning.
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Krittanawong C, Singh NK, Scheuring RA, Urquieta E, Bershad EM, Macaulay TR, Kaplin S, Dunn C, Kry SF, Russomano T, Shepanek M, Stowe RP, Kirkpatrick AW, Broderick TJ, Sibonga JD, Lee AG, Crucian BE. Human Health during Space Travel: State-of-the-Art Review. Cells 2022; 12:cells12010040. [PMID: 36611835 PMCID: PMC9818606 DOI: 10.3390/cells12010040] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 12/05/2022] [Accepted: 12/07/2022] [Indexed: 12/24/2022] Open
Abstract
The field of human space travel is in the midst of a dramatic revolution. Upcoming missions are looking to push the boundaries of space travel, with plans to travel for longer distances and durations than ever before. Both the National Aeronautics and Space Administration (NASA) and several commercial space companies (e.g., Blue Origin, SpaceX, Virgin Galactic) have already started the process of preparing for long-distance, long-duration space exploration and currently plan to explore inner solar planets (e.g., Mars) by the 2030s. With the emergence of space tourism, space travel has materialized as a potential new, exciting frontier of business, hospitality, medicine, and technology in the coming years. However, current evidence regarding human health in space is very limited, particularly pertaining to short-term and long-term space travel. This review synthesizes developments across the continuum of space health including prior studies and unpublished data from NASA related to each individual organ system, and medical screening prior to space travel. We categorized the extraterrestrial environment into exogenous (e.g., space radiation and microgravity) and endogenous processes (e.g., alteration of humans' natural circadian rhythm and mental health due to confinement, isolation, immobilization, and lack of social interaction) and their various effects on human health. The aim of this review is to explore the potential health challenges associated with space travel and how they may be overcome in order to enable new paradigms for space health, as well as the use of emerging Artificial Intelligence based (AI) technology to propel future space health research.
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Affiliation(s)
- Chayakrit Krittanawong
- Department of Medicine and Center for Space Medicine, Section of Cardiology, Baylor College of Medicine, Houston, TX 77030, USA
- Translational Research Institute for Space Health, Houston, TX 77030, USA
- Department of Cardiovascular Diseases, New York University School of Medicine, New York, NY 10016, USA
- Correspondence: or (C.K.); (B.E.C.); Tel.: +1-713-798-4951 (C.K.); +1-281-483-0123 (B.E.C.)
| | - Nitin Kumar Singh
- Biotechnology and Planetary Protection Group, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
| | | | - Emmanuel Urquieta
- Translational Research Institute for Space Health, Houston, TX 77030, USA
- Department of Emergency Medicine and Center for Space Medicine, Baylor College of Medicine, Houston, TX 77030, USA
| | - Eric M. Bershad
- Department of Neurology, Center for Space Medicine, Baylor College of Medicine, Houston, TX 77030, USA
| | | | - Scott Kaplin
- Department of Cardiovascular Diseases, New York University School of Medicine, New York, NY 10016, USA
| | - Carly Dunn
- Department of Dermatology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Stephen F. Kry
- Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | | | - Marc Shepanek
- Office of the Chief Health and Medical Officer, NASA, Washington, DC 20546, USA
| | | | - Andrew W. Kirkpatrick
- Department of Surgery and Critical Care Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada
| | | | - Jean D. Sibonga
- Division of Biomedical Research and Environmental Sciences, NASA Lyndon B. Johnson Space Center, Houston, TX 77058, USA
| | - Andrew G. Lee
- Department of Ophthalmology, University of Texas Medical Branch School of Medicine, Galveston, TX 77555, USA
- Department of Ophthalmology, Blanton Eye Institute, Houston Methodist Hospital, Houston, TX 77030, USA
- Department of Ophthalmology, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
- Department of Ophthalmology, Texas A and M College of Medicine, College Station, TX 77807, USA
- Department of Ophthalmology, University of Iowa Hospitals and Clinics, Iowa City, IA 52242, USA
- Departments of Ophthalmology, Neurology, and Neurosurgery, Weill Cornell Medicine, New York, NY 10021, USA
| | - Brian E. Crucian
- National Aeronautics and Space Administration (NASA) Johnson Space Center, Human Health and Performance Directorate, Houston, TX 77058, USA
- Correspondence: or (C.K.); (B.E.C.); Tel.: +1-713-798-4951 (C.K.); +1-281-483-0123 (B.E.C.)
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Wostyn P, Mader TH, Gibson CR, Nedergaard M. Does Long-Duration Exposure to Microgravity Lead to Dysregulation of the Brain and Ocular Glymphatic Systems? Eye Brain 2022; 14:49-58. [PMID: 35546965 PMCID: PMC9081191 DOI: 10.2147/eb.s354710] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 04/27/2022] [Indexed: 02/05/2023] Open
Abstract
Spaceflight-associated neuro-ocular syndrome (SANS) has been well documented in astronauts both during and after long-duration spaceflight and is characterized by the development of optic disc edema, globe flattening, choroidal folds, and hyperopic refractive error shifts. The exact mechanisms underlying these ophthalmic abnormalities remain unclear. New findings regarding spaceflight-associated alterations in cerebrospinal fluid spaces, specifically perivascular spaces, may shed more light on the pathophysiology of SANS. The preliminary results of a recent brain magnetic resonance imaging study show that perivascular spaces enlarge under prolonged microgravity conditions, and that the amount of fluid in perivascular spaces is linked to SANS. The exact pathophysiological mechanisms underlying enlargement of perivascular spaces in space crews are currently unclear. Here, we speculate that the dilation of perivascular spaces observed in long-duration space travelers may result from impaired cerebral venous outflow and compromised cerebrospinal fluid resorption, leading to obstruction of glymphatic perivenous outflow and increased periarterial cerebrospinal fluid inflow, respectively. Further, we provide a possible explanation for how dilated perivascular spaces can be associated with SANS. Given that enlarged perivascular spaces in space crews may be a marker of altered venous hemodynamics and reduced cerebrospinal fluid outflow, at the level of the optic nerve and eye, these disturbances may contribute to SANS. If confirmed by further studies, brain glymphatic dysfunction in space crews could potentially be considered a risk factor for the development of neurodegenerative diseases, such as Alzheimer’s disease. Furthermore, long-duration exposure to microgravity might contribute to SANS through dysregulation of the ocular glymphatic system. If prolonged spaceflight exposure causes disruption of the glymphatic systems, this might affect the ability to conduct future exploration missions, for example, to Mars. The considerations outlined in the present paper further stress the crucial need to develop effective long-term countermeasures to mitigate SANS-related physiologic changes during long-duration spaceflight.
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Affiliation(s)
- Peter Wostyn
- Department of Psychiatry, PC Sint-Amandus, Beernem, Belgium
- Correspondence: Peter Wostyn, Department of Psychiatry, PC Sint-Amandus, Reigerlostraat 10, Beernem, 8730, Belgium, Tel +32-472713719, Fax +32-50-819720, Email
| | | | - Charles Robert Gibson
- Coastal Eye Associates, Webster, TX, USA
- KBR, NASA Space Medicine Operations Division, Houston, TX, USA
| | - Maiken Nedergaard
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, NY, USA
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