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NASA NTRS2002

Spatial and temporal traction response in human airway smooth muscle cells

Tractions that cells exert on their substrates are essential in cell spreading, migration, and contraction. These tractions can be determined by plating the cells on a flexible gel and measuring the deformation of the gel by using fluorescent beads embedded just below the surface of the gel. In this article we describe the image correlation method (ICM) optimized for determining the displacement field of the gel under a contracting cell. For the calculation of the traction field from the displacement field we use the recently developed method of Fourier transform traction cytometry (FTTC). The ICM and FTTC methods are applied to human airway smooth muscle cells during stimulation with the contractile agonist histamine or the relaxing agonist isoproterenol. The overall intensity of the cell contraction (the median traction magnitude, the energy transferred from the cell to the gel, and the net contractile moment) increased after activation with histamine, and decreased after treatment with isoproterenol. Cells exhibited regional differences in the time course of traction during the treatment. Both temporal evolution and magnitude of traction increase induced by histamine varied markedly among different cell protrusions, whereas the nuclear region showed the smallest response. These results suggest that intracellular mediators of cell adhesion and contraction respond to contractile stimuli with different rates and intensities in different regions of the cell.

NASA Discipline Cell Biology↗

NASA NTRS2017

New Developments in NASA's Rodent Research Hardware for Conducting Long Duration Biomedical and Basic Research in Space

Animal models, particularly rodents, are the foundation of pre-clinical research to understand human diseases and evaluate new therapeutics, and play a key role in advancing biomedical discoveries both on Earth and in space. The National Research Councils Decadal survey emphasized the importance of expanding NASA's life sciences research to perform long duration, rodent experiments on the International Space Station (ISS) to study effects of the space environment on the musculoskeletal and neurological systems of mice as model organisms of human health and disease, particularly in areas of muscle atrophy, bone loss, and fracture healing. To accomplish this objective, flight hardware, operations, and science capabilities were developed at NASA Ames Research Center (ARC) to enhance science return for both commercial (CASIS) and government-sponsored rodent research. The Rodent Research Project at NASA ARC has pioneered a new research capability on the International Space Station and has progressed toward translating research to the ISS utilizing commercial rockets, collaborating with academia and science industry, while training crewmembers to assist in performing research on orbit. The Rodent Research Habitat provides a living environment for animals on ISS according to standard animal welfare requirements, and daily health checks can be performed using the habitats camera system. Results from these studies contribute to the science community via both the primary investigation and banked samples that are shared in publicly available data repository such as GeneLab. Following each flight, through the Biospecimen Sharing Program (BSP), numerous tissues and thousands of samples will be harvested, and distributed from the Space Life and Physical Sciences (SLPS) to Principal Investigators (PIs) through the Ames Life Science Data Archive (ALSDA). Every completed mission sets a foundation to build and design greater complexity into future research and answer questions about common human diseases. Together, the hardware improvements (enrichment, telemetry sensors, cameras), new capabilities (live animal return), and experience that the Rodent Research team has gained working with principal investigator teams and ISS crew to conduct complex experiments on orbit are expanding capabilities for long duration rodent research on the ISS to achieve both basic science and biomedical research objectives.

Shirazi, Yasaman↗

NASA NTRS1999

Role of microtubules in the contractile dysfunction of hypertrophied myocardium

OBJECTIVES: We sought to determine whether the ameliorative effects of microtubule depolymerization on cellular contractile dysfunction in pressure overload cardiac hypertrophy apply at the tissue level. BACKGROUND: A selective and persistent increase in microtubule density causes decreased contractile function of cardiocytes from cats with hypertrophy produced by chronic right ventricular (RV) pressure overloading. Microtubule depolymerization by colchicine normalizes contractility in these isolated cardiocytes. However, whether these changes in cellular function might contribute to changes in function at the more highly integrated and complex cardiac tissue level was unknown. METHODS: Accordingly, RV papillary muscles were isolated from 25 cats with RV pressure overload hypertrophy induced by pulmonary artery banding (PAB) for 4 weeks and 25 control cats. Contractile state was measured using physiologically sequenced contractions before and 90 min after treatment with 10(-5) mol/liter colchicine. RESULTS: The PAB significantly increased RV systolic pressure and the RV weight/body weight ratio in PAB; it significantly decreased developed tension from 59+/-3 mN/mm2 in control to 25+/-4 mN/mm2 in PAB, shortening extent from 0.21+/-0.01 muscle lengths (ML) in control to 0.12+/-0.01 ML in PAB, and shortening rate from 1.12+/-0.07 ML/s in control to 0.55+/-0.03 ML/s in PAB. Indirect immunofluorescence confocal microscopy showed that PAB muscles had a selective increase in microtubule density and that colchicine caused complete microtubule depolymerization in both control and PAB papillary muscles. Microtubule depolymerization normalized myocardial contractility in papillary muscles of PAB cats but did not alter contractility in control muscles. CONCLUSIONS: Excess microtubule density, therefore, is equally important to both cellular and to myocardial contractile dysfunction caused by chronic, severe pressure-overload cardiac hypertrophy.

NASA Discipline Cardiopulmonary↗

NASA NTRS1980

Change in energy expenditure and brain and adrenal content of catecholamines in rats during muscular loading and hypokinesia

In male 1-7 month old rats, the growth and the protein content of skeletal muscles were higher than in female rats while the O2 consumption and the heart rate were lower. This is combined with reduction of the thyroid gland weight and of catecholamine content in adrenals at the age of 7 months. The development of male and female rats (1-7 month) under conditions of systematic muscular loads increases the growth tempo and protein of skeletal muscles and intensifies the degree of reduction of energy expenditure and the heart rate. This is accomplished by the greater reduction of relative weight of the thyroid gland and, at the age of 7 months, by reduction of the noradrenaline content in the brainstem. Hypodynamic conditions have the exact opposite effect.

Rozanova, V. D.↗

NASA NTRS2016

Squat Biomechanical Modeling Results from Exercising on the Hybrid Ultimate Lifting Kit

Long duration space travel will expose astronauts to extended periods of reduced gravity. Since gravity is not present to aid loading, astronauts will use resistive and aerobic exercise regimes for the duration of the space flight to minimize loss of bone density, muscle mass and aerobic capacity that occurs during exposure to a reduced gravity environment. Unlike the International Space Station (ISS), the area available for an exercise device in the next generation of spacecraft is limited and therefore compact resistance exercise device prototypes are being developed. The Advanced Resistive Exercise Device (ARED) currently on the ISS is being used as a benchmark for the functional performance of these new devices. Biomechanical data collection and computational modeling aid the device design process by quantifying the joint torques and the musculoskeletal forces that occur during exercises performed on the prototype devices. The computational models currently under development utilize the OpenSim software, an open source code for musculoskeletal modeling, with biomechanical input data from test subjects for estimation of muscle and joint loads. The subjects are instrumented with reflective markers for motion capture data collection while exercising on the Hybrid Ultimate Lifting Kit (HULK) prototype device. Ground reaction force data is collected with force plates under the feet and device loading is recorded through load cells internal to the HULK. Test variables include applied device load, narrow or wide foot stance, slow or fast cadence and the harness or long bar interface between the test subject and the device. Data is also obtained using free weights for a comparison to the resistively loaded exercise device. This data is input into the OpenSim biomechanical model, which has been scaled to match the anthropometrics of the test subject, to calculate the body loads. The focus of this presentation is to summarize the results from the full squat exercises across the different test variables.

Bioengineering↗

NASA NTRS1995

Bicycle ergometer instrumentation to determine muscle and bone forces during exercise

It is hypothesized that bone loss experienced by astronauts in zero gravity conditions may be curtailed by appropriate exercise. According to Wolf's law, bone regenerates when muscles produce stresses by pulling on the bone during daily activity and/or exercise on Earth. to use this theory to prevent or decrease bone loss, one needs to quantify musculoskeletal loads and relate them to bone density changes. In the context of the space program, it is desirable to determine musculoskeletal loads during exercise (using the bicycle ergometer in this case) so that one may make similar measurements on Earth and in space. In this manner, load measurements on Earth may be used as reference to generate similar loads during exercise in space. The work reported in this document entails a musculoskeletal load measurement system that, when complete, will provide forces at muscle insertion points and other contact points, on bone. This data will be used by Dr. Beth A. Todd, who is also a SSF working with Dr. Shackelford, as input to a finite element model of bone sections to determine stress distributions. A bicycle ergometer has been instrumented to measure parameters needed to determine musculoskeletal forces during exercise. A primary feature of the system is its compactness. It uses small/light sensors without line-of-sight requirements. The system developed includes sensors, signal processing, a data acquisition system, and software to collect the data. The sensors used include optical encoders to measure position and orientation of the pedal (foot), accelerometers to determine kinematic parameters of the shank and thigh, load cells to measure pedal forces on the sagittal plane, and EMG probes to measure muscle activity. The signals are processed using anti-aliasing filters and amplifiers. The sensors' output is digitized using 30 channels of a board mounted inside a 486 class PC. A program sets the data acquisition parameters and collects data during a time period specified by the user. The data is put directly into a file on the hard disk in binary form. The 30 channels are sampled at 200 KHz, and each 30 channel scan is done at a rate of 1000 Hz. The instrumented ergometer has been flown in the KC-135 zero-gravity (zero-g) flight to collect information needed to determine musculoskeletal forces under these conditions. Similar information has been collected in 1-g conditions for comparision with the results from the zero-g case. At this time, the sets of data from both experiments are being processed. An existing methodology will be used to determine the kinematic parameters of the shank and thigh using accelerometer and encoder data. This methodology was developed during the fellow's previous NASA/ASEE fellowship and thanks to a Director's Grant. In the future, a methodology to determine the musculoskeletal forces using Newton's Law of Motion and optimization techniques will be developed to determine forces exerted by particular muscles.

Figueroa, Fernando↗

NASA NTRS2017

Biomechanical Modeling Analysis of Loads Configuration for Squat Exercise

INTRODUCTION: Long duration space travel will expose astronauts to extended periods of reduced gravity. Since gravity is not present to assist loading, astronauts will use resistive and aerobic exercise regimes for the duration of the space flight to minimize loss of bone density, muscle mass and aerobic capacity that occurs during exposure to a reduced gravity environment. Unlike the International Space Station (ISS), the area available for an exercise device in the next generation of spacecraft for travel to the Moon or to Mars is limited and therefore compact resistance exercise device prototypes are being developed. The Advanced Resistive Exercise Device (ARED) currently on the ISS is being used as a benchmark for the functional performance of these new devices. Biomechanical data collection and computational modeling aid the device design process by quantifying the joint torques and the musculoskeletal forces that occur during exercises performed on the prototype devices. METHODS The computational models currently under development utilize the OpenSim [1] software platform, consisting of open source code for musculoskeletal modeling, using biomechanical input data from test subjects for estimation of muscle and joint loads. The OpenSim Full Body Model [2] is used for all analyses. The model incorporates simplified wrap surfaces, a new knee model and updated lower body muscle parameters derived from cadaver measurements and magnetic resonance imaging of young adults. The upper body uses torque actuators at the lumbar and extremity joints. The test subjects who volunteer for this study are instrumented with reflective markers for motion capture data collection while performing squat exercising on the Hybrid Ultimate Lifting Kit (HULK) prototype device (ZIN Technologies, Middleburg Heights, OH). Ground reaction force data is collected with force plates under the feet, and device loading is recorded through load cells internal to the HULK. Test variables include the applied device load and the dual cable long bar or single cable T-bar interface between the test subject and the device. Data is also obtained using free weights with the identical loading for a comparison to the resistively loaded exercise device trials. The data drives the OpenSim biomechanical model, which has been scaled to match the anthropometrics of the test subject, to calculate the body loads. RESULTS Lower body kinematics, joint moments, joint forces and muscle forces are obtained from the OpenSim biomechanical analysis of the squat exercises under different loading conditions. Preliminary results from the model for the loading conditions will be presented as will hypotheses developed for follow on work.

Human Factors Engineering↗

NASA NTRS1990

Human skeletal muscle responses to spaceflight and possible countermeasures

The current status of knowledge concerning the effects of unweighting skeletal muscle is summarized. The results of both ground-based and space-based animal studies are reviewed which show that there is rapid loss in muscle mass, primarily in slow-twitch muscle, of the rat during unweighting of muscle. There is also a shift in the myosin isoforms with muscles such that slow-twitch muscles take on many of the characteristics of fast-twitch muscles. Ground-based studies in human suggest that programs of electrical stimulation can be developed to simulate normal muscular contractions. Attempts to develop countermeasures to the adverse effects of space travel on muscular functions in humans have not been successful to date.

Gollnick, Philip D.↗

NASA NTRS1993

A musculoskeletal model of the elbow joint complex

This paper describes a musculoskeletal model that represents human elbow flexion-extension and forearm pronation-supination. Musculotendon parameters and the skeletal geometry were determined for the musculoskeletal model in the analysis of ballistic elbow joint complex movements. The key objective was to develop a computational model, guided by optimal control, to investigate the relationship among patterns of muscle excitation, individual muscle forces, and movement kinematics. The model was verified using experimental kinematic, torque, and electromyographic data from volunteer subjects performing both isometric and ballistic elbow joint complex movements. In general, the model predicted kinematic and muscle excitation patterns similar to what was experimentally measured.

Gonzalez, Roger V.↗

NASA NTRS2000

Genetic dissection of cardiac growth control pathways

Cardiac muscle cells exhibit two related but distinct modes of growth that are highly regulated during development and disease. Cardiac myocytes rapidly proliferate during fetal life but exit the cell cycle irreversibly soon after birth, following which the predominant form of growth shifts from hyperplastic to hypertrophic. Much research has focused on identifying the candidate mitogens, hypertrophic agonists, and signaling pathways that mediate these processes in isolated cells. What drives the proliferative growth of embryonic myocardium in vivo and the mechanisms by which adult cardiac myocytes hypertrophy in vivo are less clear. Efforts to answer these questions have benefited from rapid progress made in techniques to manipulate the murine genome. Complementary technologies for gain- and loss-of-function now permit a mutational analysis of these growth control pathways in vivo in the intact heart. These studies have confirmed the importance of suspected pathways, have implicated unexpected pathways as well, and have led to new paradigms for the control of cardiac growth.

NASA Program Biomedical Research and Countermeasur↗

NASA NTRS2003

Accomplishments in Bioastronautics Research Aboard International Space Station

The seventh long-duration expedition crew is currently in residence aboard International Space Station (ISS), continuing a permanent human presence in space that began in October 2000. During that time, expedition crews have been operators and subjects for 16 Human Life Sciences investigations, to gain a better understanding of the effects of long-duration space flight on the crew members and of the environment in which they live. Investigations have been conducted to study the radiation environment in the station as well as during extravehicular activity (EVA); bone demineralization and muscle deconditioning; changes in neuromuscular reflexes, muscle forces and postflight mobility; causes and possible treatment of postflight orthostatic intolerance; risk of developing kidney stones; changes in pulmonary function caused by long-duration flight as well as EVA; crew and crew-ground interactions; and changes in immune function. The experiment mix has included some conducted in flight aboard ISS as well as several which collected data only pre- and postflight. The conduct of these investigations has been facilitated by the Human Research Facility (HRF). HRF Rack 1 became the first research rack on ISS when it was installed in the US laboratory module Destiny in March 2001. The rack provides a core set of experiment hardware to support investigations, as well as power, data and commanding capability, and stowage. The second HRF rack, to complement the first with additional hardware and stowage capability, will be launched once Shuttle flights resume. Future years will see additional capability to conduct human research on ISS as International Partner modules and facility racks are added to ISS . Crew availability, both as a subject count and time, will remain a major challenge to maximizing the science return from the bioastronautics research program.

Uri, John J.↗

NASA NTRS2020

Circulating miRNA Signature Predicts Health Risks Associated with Cancer and Spaceflight

Biological risks associated with space radiation and microgravity are major concerns for long-term space travel. Through a Systems Biology approach, our previous NASA work has shown both TGF signaling pathways and miRNAs have a critical impact on defining health risks with and without space irradiation. We hypothesize that circulating microRNA (miRNA) signatures are driving microvascular disease and muscle degeneration associated with accelerating aging and will be enhanced by exposure to the space environment (radiation and microgravity). We are investigating this hypothesis with both in vivo and in vitro models to test novel antagonist therapies to these miRNA signatures as countermeasures to reduce space radiation-induced health risks. A comprehensive Systems Biology approach is utilized to examine the influence by high atomic number by high (H) atomic number (Z) and energy (E) (HZE) irradiation. To simulate low-dose exposure due to galactic cosmic rays (GCR), we used ions, energy, and doses determined by a NASA consensus formula of 7 different ions to represent GCR (referred to as GCR sim model). To similate high-dose radiation exposure due to solar particle events (SPE), we used a solar particle event (SPE) sim model which gave a total dose of 1Gy protons with energy ranges from 50MeV to 150MeV. C57BL/6 wild-type female mice were utilized for the irradiations with our established simulated microgravity model (hindlimb suspension model) and an in vitro 3D microvasculature tissue model under simulated microgravity (clinostat) conditions was also irradiated. To expand on the circulating miRNA signature determined from our preliminary data, we determined a group of conserved miRNAs which are commonly being regulated in the majority of the organs and tissues throughout the host using our established techniques. MiRNA-sequencing was done on serum (at time of sacrifice), liver, heart, and muscle (soleus muscle) tissue for all radiation groups. Additional validation of the key miRNAs was performed by droplet digital PCR (ddPCR). This revealed a key circulating miRNA signature (consisting of multiple miRNAs) impacting cardiovascular and muscular disease risk. Further in vitro experiments with CRISPR/Cas9 system to knockout the key miRNA signatures, novel self-delivering antagomirs, overexpression of the miRNAs test the functional impact of the miRNA signatures on both microvascular disease and muscle degeneration due to space irradiation. The current work has started to allow the possible development of a novel minimally invasive miRNA based radioprotector to be used as a countermeasure for space radiation. Collectively, understanding of how whole body space radiation impacts microvascular and tissue degeneration through circulating miRNAs will greatly enhance health risk prognostication and provide possible new mechanisms for protection against space radiation. This work is supported by the Translational Research Institute through NASA Cooperative Agreement NNX16AO69A (T-0404) awarded to AB.

Beheshti, Afshin↗

NASA NTRS1991

Dynamic inter-limb resistance exercise device for long-duration space flight

Essential for fitness on Earth, resistive exercise is even more important for astronauts, who must maintain muscle and bone strength in the absence of gravity. To meet this need, designers and scientists at NASA Ames Research Center, Life Science Division, have worked to develop more effective exercise devices for long-duration exposure to microgravity. One of these concepts is the Inter-Limb Resistance Device which allows the subject to exercise one limb directly against another, strengthening muscle groups in the arms, legs, and back. It features a modular harness with an inelastic cable and instrumented pulley. Forces similar to other high resistance exercise equipment are generated. Sensors in the pulley measure force and velocity for performance feedback display and data acquisition. This free-floating apparatus avoids vibration of sensitive experiments on board spacecraft. Compact with low mass, this hardware is also well suited for a 'safe haven' from radiation on board Space Station Freedom, and may prove useful in confined environments on Earth, such as Antarctic stations, submarines, and other underwater habitats. Potential spin-offs of this technology include products for personal strengthening and cardiovascular conditioning, rehabilitation of hospital patients, fitness exercise for the disabled, and retraining after sports injuries.

Schwandt, Douglas F.↗

NASA NTRS2025

Countermeasures for Mitigation of Sensorimotor Decrements Following Head-Down Tilt Bed Rest

BACKGROUND Astronauts experience postflight disturbances in postural and locomotor control due to sensorimotor adaptations during spaceflight. These alterations may have adverse consequences if a rapid egress is required after landing. Although exercise is partially effective for mitigating cardiovascular and muscular deconditioning, additional countermeasures are needed to further preserve sensorimotor function. Proprioception training and electrical muscle stimulation (EMS) are two promising in-flight countermeasures. Since prolonged head down tilt bed rest (HDTBR) is a spaceflight analog for body unloading and causes postural and locomotor control decrements that parallel those observed after spaceflight, it can be used to facilitate the development of these countermeasures. METHODS This study will determine the effects of proprioception training and EMS on functional task performance and sensorimotor function following 60 days of 6° HDTBR. Subjects will be randomly assigned to one of four groups: 1) an EMS arm, 2) a proprioception training arm, 3) an exercise plus proprioceptive training arm, and 4) a control arm. The EMS countermeasure will include daily bilateral stimulation of selected bilateral lower extremity muscles (30 minutes per session). Proprioception training will be performed three days per week (25 minutes per session) consisting of body-loaded postural tasks in the horizontal position on an air bearing sled. Exercise training will mimic current protocols used on the International Space Station, but treadmill aerobic exercise will be replaced with additional cycling aerobic exercise. Primary outcome measures will include pre- and post- HDTBR functional tests that require high demand for dynamic control of postural stability. Secondary measures will be used to explore key physiological changes that underlie countermeasure benefits. All HDTBR and data collection activities will be completed by the German Aerospace Center (DLR) at the :envihab facility. Given the constrained samples size, a Bayesian modelling approach will be used to quantify the probability that there is an effect of a given magnitude. HARDWARE AND PROTOCOL DEVELOPMENT Final hardware modifications and protocol developments were completed in preparation for Campaign 1, which began in September 2024. These included shipment, setup, and operator training for the transportable gravity bed, horizontal squat device, foam obstacle course, EMS devices, leg dexterity system, foot sole skin sensitivity system, and Radiofrequency Echographic Multi Spectrometry (REMS) ultrasound device. In addition, specialized protocols were developed for data collection using DLR’s equipment, including muscle morphology magnetic resonance imaging (MRI), optical coherence tomography, venous blood flow MRI and ultrasound, muscle ultrasound and impedance, and skin blood flow ultrasound. We will present early data from the first campaign, which concluded in November, 2024. These will be compared with previous data from the recent 30-day HDTBR campaigns (Spaceflight associated neuro-ocular syndrome countermeasures (SANS-CM)) conducted at DLR. RELEVANCE The deliverable from this project will be proof-of-concept sensorimotor countermeasure designs for functional task performance with full assessment of efficacy in a spaceflight analog. If one or more countermeasures are effective, they will be translated for validation with the suite of operationally implemented in-flight countermeasures.

T R Macaulay↗

NASA NTRS1996

Cloning and characterization of the murine homolog of the sno proto-oncogene reveals a novel splice variant

The cellular function(s) of the SNO protein remain undefined. To gain a better understanding of possible developmental roles of this cellular proto-oncogene, we have cloned two murine sno cDNAs and have investigated their expression patterns in embryonic and postnatal tissues. A single major transcript of 7.5 kb is detected in multiple tissues by Northern blot. However, reverse transcriptase polymerase chain reaction (RT-PCR) and RNAse protection assays revealed a novel splice variant in every tissue examined. Two isoforms, termed sno N and sno-dE3 (dE3, deletion within exon 3), were identified. The sno-dE3 isoform employs a novel 5' splice site located within the coding region of the third exon and deletes potential kinase recognition motifs. Transcripts of both sno isoforms accumulate ubiquitously but are most abundant in the developing central nervous system. The in situ hybridization patterns of sno expression during murine development suggest potential roles in tissues with a high degree of cellular proliferation. Expression in terminally differentiated tissues such as muscle and neurons indicates that SNO may have multiple functional activities.

Non-NASA Center↗

NASA NTRS1991

Musculoskeletal discipline science plan

Life sciences research in the musculoskeletal discipline must identify possible consequences of weightlessness on this system, understand the mechanisms of these effects, and develop effective and operationally practical countermeasures to protect crewmembers. The musculoskeletal system is highly plastic in that is possesses the inherent capability to adapt its structural and functional properties in accordance with the type and degree of stimuli imposed on it. Prolonged space travel is essentially a period of significant unloading of the musculoskeletal system. This results in adaptive responses in the structure and function of this system, placing it on the low end of a continuum from one of complete disuse to one of maximal use. There is a high probability that the musculoskeletal system is functionally impaired with increasing duration of weightlessness. The purpose of this Discipline Science Plan is to provide a conceptual strategy for NASA's Life Sciences division research and development activities in the area of musculoskeletal function. This document summarizes the current status of the program, outlines available knowledge, establishes goals and objectives, identifies science priorities, and defines research opportunities, which encompass critical questions in the subdiscipline areas (e.g., muscle, bone, and other musculoskeletal connective tissues). These science activities include ground-based and flight; basic, applied, and operational; and animal and human research and development. This document contains a general plan that will be used by both NASA Headquarters Program Offices and the field centers to review and plan basic, applied, and operational intramural and extramural research and development activities in this area.

Source record↗

NASA NTRS2014

Retrospective Analysis of Inflight Exercise Loading and Physiological Outcomes

Astronauts perform exercise throughout their missions to counter the health declines that occur as a result of long-term exposure to weightlessness. Although all astronauts perform exercise during their missions, the specific prescriptions, and thus the mechanical loading, differs among individuals. For example, inflight ground reaction force data indicate that subject-specific differences exist in foot forces created when exercising on the second-generation treadmill (T2) [1]. The current exercise devices allow astronauts to complete prescriptions at higher intensities, resulting in greater benefits with increased efficiency. Although physiological outcomes have improved, the specific factors related to the increased benefits are unknown. In-flight exercise hardware collect data that allows for exploratory analyses to determine if specific performance factors relate to physiological outcomes. These analyses are vital for understanding which components of exercise are most critical for optimal human health and performance. The relationship between exercise performance variables and physiological changes during flight has yet to be fully investigated. Identifying the critical performance variables that relate to improved physiological outcomes is vital for creating current and future exercise prescriptions to optimize astronaut health. The specific aims of this project are: 1) To quantify the exercise-related mechanical loading experienced by crewmembers on T2 and ARED during their mission on ISS; 2) To explore relationships between exercise loading variables, bone, and muscle health changes during the mission; 3) To determine if specific mechanical loading variables are more critical than others in protecting physiology; 4) To develop methodology for operational use in monitoring accumulated training loads during crew exercise programs. This retrospective analysis, which is currently in progress, is being conducted using data from astronauts that have flown long-duration missions onboard the ISS and have had access to exercise on the T2 and the Advanced Resistive Exercise Device (ARED). The specific exercise prescriptions vary for each astronaut. General exercise summary metrics will be developed to quantify exercise intensities, volumes, and durations for each subject. Where available, ground reaction force data will be used to quantify mechanical loading experienced by each astronaut. These inflight exercise metrics will be investigated relative to changes in pre- to post-flight bone and muscle health to identify which specific variables are related with improved or degraded physiological outcomes. The information generated from this analysis will fill gaps related to typical bone loading characterization, exercise performance capability, exercise volume and efficiency, and importance of exercise hardware. In addition, methods for quantification of exercise loading for use in monitoring the exercise programs during future space missions will be explored with the intent to inform exercise scientists and trainers as to the critical aspects of inflight exercise prescriptions.

Ploutz-Snyder, L. L.↗

NASA NTRS2014

Maiden Voyage of the Rodent Habitat on ISS: Opportunities for Investigating Molecular Mechanisms and Biomedical Consequences of Long Duration Spaceflight

Research using rodents is an essential tool for advancing biomedical research on Earth and in space. The National Research Counsel’s Decadal survey (1) emphasized the importance of expanding NASAs life sciences research to perform long duration, rodent experiments on the International Space Station (ISS). To accomplish this objective, flight hardware, operations, and science capabilities were developed at NASA ARC to support both commercial and government-sponsored research. In preparation for the maiden voyage of the Rodent Habitat hardware and operations system (Rodent Research-1), and in close consultation with a Science Working Group comprised of veterinarians and experienced spaceflight investigators, we modified existing Animal Enclosure Module hardware, developed new hardware, operations, and science activities, and performed a series of ground-based verification tests. Preflight, ground based hardware tests included a simulation of SpaceX Dragon launch conditions (vibration and hypergravity) using the Transporter, and also two long-term biocompatibility tests (32 and 92 days) using the Habitat developed for long term housing on the ISS. The launch simulation test showed that adult mice housed in Transporter hardware adapted well, even if launch simulation was followed by a period of simulated weightlessness (via hind limb unloading). The biocompatibility tests demonstrated that the Habitat successfully supported animal health and also provided a useful video imaging system that enables frequent monitoring of animal health and behavior by veterinary and scientific experts on the ground, independent of ISS crew intervention. At the conclusion of all tests, mice were deemed healthy and suitable for conducting biological research. Additional preflight analyses of tissues preserved by freezing or fixation for gene expression analyses revealed that spleen and liver tissues recovered under conditions that simulated on-orbit activities yielded high quality RNA (RIN values 8-10) and liver enzyme activities and protein content (e.g. catalase). In addition, new methods were developed to optimize future science return by dissecting tissues post-euthanasia and storage. Various tissues were harvested from either intact or partially dissected, frozen carcasses after storage for ~2-6 months; most of the tissues (brain, heart, kidney, eye, adrenal glands and skeletal muscle) were of high RNA quality for science return, whereas some tissues (small intestine, bone marrow and bones) were not. These data demonstrated the protocols developed for future flight experiments supported science return despite delayed preservation post-euthanasia or prolonged storage, and furthermore, that high-quality RNA samples from many different tissues can be recovered by dissection following prolonged storage of the tissue in situ at -80˚C. The first flight experiments carrying 20 mice were launched on Sept 21, 2014 in an unmanned Dragon Capsule, SpaceX4; Rodent Research-1 is dedicated to achieving both NASA validation and CASIS science objectives. Ground based control groups (housed in flight hardware or standard cages) were maintained in environmental chambers at Kennedy Space Center. Crewmembers previously trained in animal handling transferred mice from the Transporter into Habitats under simultaneous veterinary supervision by video streaming and were deemed healthy. Health and behavior of all mice on the ISS was monitored by video feed on a daily basis. The 10 mice for validation (16wk old, female C57Bl6/J) ambulated freely and actively throughout the Habitat, relying heavily on their forelimbs for locomotion. The first on-orbit dissections of mice were performed successfully on Oct 12 and 13, 2014, and the validation mice will reside on ISS for up to 30 days. In conclusion, new capability for long duration rodent research is under development, including in-flight sample collection (which avoids the complication of reentry); results obtained to date will be described. This new Rodent Research system enables achievement of both basic science and translational research objectives to advance human exploration of space.

maiden voyage↗