(D-141) Increased Gravitational Loading Mitigates Performance Deficits During Spaceflight

Friday, October 13, 2023

3:30 PM – 4:30 PM PDT

Location: Exhibit Hall - Row D - Poster # 141

Presenting Author(s)

LK

Leslie Kim

Undergraduate
University of Virginia
Annandale, Virginia, United States

Co-Author(s)

CP

Chirayu Patel

PhD Candidate
Wake Forest University School of Medicine, United States

Primary Investigator(s)

JW

Jeffrey Willey

Section Head of Radiation Oncology
Wake Forest University School of Medicine, United States

Introduction::

Mechanical loading is required for the maintenance of the musculoskeletal system. Our lab has previously shown cartilage and meniscal degradation from reduced weight-bearing via hindlimb unloading and spaceflight aboard the International Space Station (ISS) during the Rodent Research-9 mission (RR9). This is a major concern for astronauts during and after long duration spaceflight, as they may be at increased risk for reduced performance and early-onset arthritis. Artificial gravity via centripetal acceleration is one possible approach to alleviate these deleterious changes. The Joint Partial Gravity (Rodent Research)-Mouse Habitat Unit 8 mission (MHU8) exposed mice to partial G-exposures via centrifugation aboard the ISS. We measured altered gait of mice during spaceflight to assess artificial gravity via centrifugation as a countermeasure to performance deficits during long-duration spaceflight as part of the MHU8 mission to the ISS.

Materials and Methods::

Twenty-three 10-week-old C57bl/6 male mice spent 30 days aboard the ISS with exposure to varying amounts of gravitational loading (μG, 0.33G, 0.67G, 1G, n=5/6 per group). The animals were singly housed in centrifuge cages developed by the Japanese Aerospace Exploration Agency (JAXA), which allowed for the creation of partial G-exposures on the ISS. The study has corresponding age-matched ground (GC, n=12) and vivarium controls (VIV, n=12). Pre-flight and post-flight gait analysis was performed longitudinally on left limbs utilizing the portable DigiGait System. Gait signals were collected over 4-8 consecutive strides at a walking speed of 17 cm/s, and artificial intelligence was utilized to determine paw positions relative to the treadmill belt, resulting in gait signals for each limb. The parameters that were selected for analysis were those that have been reported by previous spaceflight studies utilizing the DigiGait to measure gait changes [1].

Results, Conclusions, and Discussions:: Animals exposed to long duration microgravity in isolation failed to perform (i.e. locomote) and were excluded from the results. Animals from the 0.33G group had similar performance failures and the group size was limited (n=3). Left hind limb swing time and swing stride % increased (Δswing time: 0.33G +243.2%, 0.67G +82.3%, 1G +20.0% vs GC +12.2%; Δswing stride %: 0.33G +136.0%, 0.67G +54.8%, 1G +4.4% vs GC +3.5%), and stance/swing and stance time decreased (Δstance/swing: 0.33G -81.2%, 0.67G -46.6, 1G -4.1% vs GC -1.6%; Δstance time: 0.33G -55.0%, 0.67G -13.4%, 1G +0.3% vs GC +5.0%) in a G-level dose dependent manner in flight animals post-flight compared to ground controls (Fig 1). Left forelimb swing stride %, stride length, and stride time increased (Δswing stride %: 0.33G +75.9%, 0.67G +12.5%, 1G +10.0% vs GC +10.3%; Δstride length: 0.33G +100.6%, 0.67G +35.4%, 1G +14.2% vs GC +0.7%; Δstride time: 0.33G +100.5%, 0.67G +35.7%, 1G +13.4% vs GC +1.2%), and brake stride % decreased (Δbrake stride %: 0.33G -42.0%, 0.67G -27.4%, 1G -18.5% vs GC -6.3) in a G-level dose dependent manner in flight animals post-flight compared to ground controls (Fig 2). These changes in gait parameters have been associated with impaired neuromuscular function [1, 2] and indicate that reduced load bearing at low gravity conditions (0.3G) can impair astronaut performance. Preserved gait parameters at higher gravity conditions (0.6G and 1G), indicate that gravitational loading reduces impaired neuromuscular function during spaceflight. Increased load bearing as a result of artificial gravity via centrifugation may provide a novel countermeasure against impaired neuromuscular function to prevent performance deficits during long duration spaceflight.

Acknowledgements (Optional): :

This project was supported by NASA (NASA 80NSSC21K0544, NASA 80NSSC21K0294, NASA NNX15AB50G) and in part by the NSF REU Site (Award #1950281) in the Department of Biomedical Engineering at Wake Forest University School of Medicine.

References (Optional): :

[1] Kwok, Andy T et al. “Altered rodent gait characteristics after ~35 days in orbit abroad the International Space Station.” Life Sciences in Space Research vol. 24, 29 October 2019.

[2] Vincelette, Jon et al. “Gait Analysis in a murine model of collagen-induced arthritis.” Arthritis Research & Therapy vol. 9, 24 November 2007.