Spaceflight results in a number of adaptations to skeletal muscle including atrophy and shifts towards faster muscle fiber types. To identify changes in gene expression that may underlie these adaptations microarray expression analysis was performed on gastrocnemius from mice flown on the STS-108 shuttle flight (11 days 19 hours) versus mice maintained on earth for the same period. Additionally to identify changes that were due to unloading and reloading microarray analyses were conducted on calf muscle from ground-based mice subjected to hindlimb suspension (12 days) and mice subjected to hindlimb suspension plus a brief period of reloading (3.5 hours) to simulate the time between landing and sacrifice of the spaceflight mice.

Prolonged residence of mice in spaceflight is a scientifically robust and ethically ratified model of muscle atrophy caused by continued unloading. Under the Rodent Research Program of NASA we assayed the genomic and metabolomics perturbations in the quadriceps of C57BL/6j male mice that lived on the spaceflight (FLT) or at Ground Control (CTR) for approximately four weeks. Wet weight of quadriceps were significantly reduced in FLT mice. Deep next generation sequencing and untargeted mass spectroscopic assay interrogated the gene-metabolite landscape of same tissues. A majority of top ranked differentially suppressed genes in FLT encode proteins from myosin or troponin family suggesting a sarcomere alteration in space. Significantly enriched gene-metabolite networks were found linked to saromeric integrity immune fitness and oxidative stress response; all inhibited in space as per in silico prediction. A significant loss of FLT mitochondrial DNA copy numbers underlined the energy deprivation associated with spaceflight induced stress and this hypothesis was reinforced by the omics analysis that showed inhibited networks related to protein lipid and carbohydrate metabolism and ATP synthesis and hydrolysis. Finally we reported a list of upstream regulators which could be targeted for next generation therapeutic intervention for the betterment of the musculoskeletal system in male mice subjected to chronic disuse.

Microgravity exposure as well as chronic muscle disuse are two of the main causes of physiological adaptive skeletal muscle atrophy in humans and murine animals in physiological condition. The aim of this study was to investigate at both morphological and global gene expression level skeletal muscle adaptation to microgravity in mouse soleus and extensor digitorum longus (EDL). Adult male mice C57BL/N6 were flown aboard the BION-M1 biosatellite for 30 days on orbit (BF) or housed in a replicate flight habitat on Earth (BG) as reference flight control. In this study we investigated for the first time gene expression adaptation to 30 days of microgravity exposure in mouse soleus and EDL highlighting potential new targets for improvement of countermeasures able to ameliorate or even prevent microgravity-induced atrophy in future spaceflights. Overall Design: C57BL/N6 mice were randomly divided in 3 groups: Bion Flown (BF) mice flown aboard the Bion M1 biosatellite in microgravity environment for 30 days; Bion Ground (BG) mice housed in the same habitat of flown animals but exposed to earth gravity; and Flight Control (FC) mice housed in a standard animal facility.

Spaceflight imposes the risk of skeletal muscle atrophy for astronauts. The understanding of muscle atrophy because of spaceflight is limited but continued efforts are essential for developing countermeasures of this effect. A distinct difference between spaceflight-induced muscle atrophy and other forms of atrophy is the additional effect of cosmic rays in outer space. To study spaceflight-induced muscle atrophy we performed two ground-based models of microgravity in a low dose radiation environment and studied transcriptional changes in rat soleus muscle using microarray technology.

Prolonged residence of mice in spaceflight is a scientifically robust and ethically ratified model of muscle atrophy caused by continued unloading. Under the Rodent Research Program of NASA, we assayed the genomic and metabolomics perturbations in the quadriceps of C57BL/6J male mice that lived on the spaceflight (FLT) or at Ground Control (CTR) for approximately four weeks. Wet weight of quadriceps were significantly reduced in FLT mice. Deep next generation sequencing and untargeted mass spectroscopic assay interrogated the gene-metabolite landscape of same tissues. A majority of top ranked differentially suppressed genes in FLT encode proteins from myosin or troponin family suggesting a sarcomere alteration in space. Significantly enriched gene-metabolite networks were found linked to saromeric integrity, immune fitness and oxidative stress response; all inhibited in space as per in silico prediction. A significant loss of FLT mitochondrial DNA copy numbers underlined the energy deprivation associated with spaceflight induced stress, and this hypothesis was reinforced by the omics analysis that showed inhibited networks related to protein, lipid and carbohydrate metabolism, and ATP synthesis and hydrolysis. Finally, we reported a list of upstream regulators, which could be targeted for next generation therapeutic intervention for the betterment of the musculoskeletal system in male mice subjected to chronic disuse. Abbreviation Key: Sham surgical procedure done (Sh); non-surgical control (NS); Ground Control group (G); Flight Group (F); Whole Body frozen as sample on ISS (W).

The objective of the Rodent Research-6 (RR-6) study was to evaluate muscle atrophy in mice during spaceflight and to test the efficacy of a novel therapeutic to mitigate muscle wasting. The experiment involved an implantable subcutaneous nanochannel delivery system (nDS; between scapula) which delivered the drug formoterol (FMT; a selective Beta-2 adrenoceptor agonist) over the course of time. To this end a cohort of forty 32-weeks-old female C57BL/6NTac mice were either sham operated. or implanted with vehicle or treatment-filled nDS and launched in two Transporters (20 mice per Transporter) on SpaceX-13 on December 15 2017. They were transferred to Rodent Habitats onboard the International Space Station (ISS) and maintained in microgravity for 29 days (N=20 Live Animal Return [LAR]) or >50 days (N=20 ISS Terminal). After 29 days the 20 LAR animals were returned live to back to Earth on January 13 2018. After splashdown the animals were ambulatory on-ground for ~4 days until all subjects were processed during one day of dissections. There were two Baseline groups of animals sacrificed (LAR Baseline & FLT Baseline; N=20; 40 animals; ~36 weeks old) at Kennedy Space Center (KSC; 12/9/17). A Ground Control group mimicked the Flight LAR group which was housed at KSC then shipped alive to Novartis facilities where both the LAR and LAR Ground Control groups were processed (~41 weeks old; 1/16/18). All were anesthetized with isoflurane blood samples were obtained by closed-chest cardiac puncture and the animals were euthanized by exsanguination and thoracotomy. The 20 ISS Terminal mice were anesthetized via intraperitoneal injection of ketamine/xylazine/acepromazine over the course of a four days of dissections (2/6/18 until 2/9/18; 53-56 days after launch; 44 weeks old at time of on-orbit dissections). Blood samples and euthanasia were conducted the same as LAR and Baseline. Following blood draw and hind limb dissection the ISS-terminal animal carcasses were wrapped in aluminum foil placed in a ziploc bag and placed in storage at -80C or colder until return. The ISS-terminal Ground Controls (at KSC) followed the same euthanasia timeline methods and preservation. The final processing of frozen ISS-terminal frozen ISS-terminal Ground Controls and frozen 0-day FLT baseline animals were completed at Houston Methodist Research Institute in Houston TX (5/21/18 until 5/24/18). GeneLab received samples of dorsal skin from only sham treated animals (no drug treated animals) from the following groups Flight: LAR (n=9) ISS Terminal (n=9); Ground Controls: LAR GC (N=9) ISS Terminal GC (N=10) LAR Baseline (n=10) ISS Terminal Baseline (n=6). Total RNA was extracted and sequenced at a target depth of 60 M clusters per sample (ribodepleted paired end 150).

Microgravity exposure as well as chronic muscle disuse are two of the main causes of physiological adaptive skeletal muscle atrophy in humans and murine animals in physiological condition. The aim of this study was to investigate at both morphological and global gene expression level skeletal muscle adaptation to microgravity in mouse soleus and extensor digitorum longus (EDL). Adult male mice C57BL/N6 were flown aboard the BION-M1 biosatellite for 30 days on orbit (BF) or housed in a replicate flight habitat on Earth (BG) as reference flight control. In this study we investigated for the first time gene expression adaptation to 30 days of microgravity exposure in mouse soleus and EDL highlighting potential new targets for improvement of countermeasures able to ameliorate or even prevent microgravity-induced atrophy in future spaceflights. Overall Design: C57BL/N6 mice were randomly divided in 3 groups: Bion Flown (BF) mice flown aboard the Bion M1 biosatellite in microgravity environment for 30 days; Bion Ground (BG) mice housed in the same habitat of flown animals but exposed to earth gravity; and Flight Control (FC) mice housed in a standard animal facility.

Among the physiological consequences of extended spaceflight are loss of skeletal muscle and bone mass. One signaling pathway that plays an important role in maintaining muscle and bone homeostasis is that regulated by the secreted signaling proteins myostatin (MSTN) and activin A. Here we used both genetic and pharmacological approaches to investigate the effect of targeting MSTN/activin A signaling in mice that were sent to the International Space Station. Wild type mice lost significant muscle and bone mass during the 33 d spent in microgravity. Muscle weights of Mstn -/- mice which are about twice those of wild type mice were largely maintained during spaceflight. Systemic inhibition of MSTN/activin A signaling using a soluble form of the activin type IIB receptor (ACVR2B) which can bind each of these ligands led to dramatic increases in both muscle and bone mass with effects being comparable in ground and flight mice. Exposure to microgravity and treatment with the soluble receptor each led to alterations in numerous signaling pathways which were reflected in changes in levels of key signaling components in the blood as well as their RNA expression levels in muscle and bone. These findings have implications for therapeutic strategies to combat the concomitant muscle and bone loss occurring in people afflicted with disuse atrophy on Earth as well as in astronauts in space especially during prolonged missions.

The objective of the Rodent Research-6 (RR-6) study was to evaluate muscle atrophy in mice during spaceflight and to test the efficacy of a novel therapeutic to mitigate muscle wasting. The experiment involved an implantable subcutaneous nanochannel delivery system (nDS; between scapula) which delivered the drug formoterol (FMT; a selective Beta-2 adrenoceptor agonist) over the course of time. To this end a cohort of forty 32-weeks-old female C57BL/6NTac mice were either sham operated or implanted with vehicle or treatment-filled nDS launched in two Transporters (20 mice per Transporter) on SpaceX-13 on December 15 2017. They were transferred to Rodent Habitats onboard the International Space Station (ISS) and maintained in microgravity for 29 days (N=20 Live Animal Return [LAR]) or >50 days (N=20 ISS Terminal). After 29 days the 20 LAR animals were returned live to back to Earth on January 13 2018,. After splashdown the animals were ambulatory on-ground for ~4 days until all subjects were processed during one day of dissections. There were two Baseline groups of animals sacrificed (LAR Baseline & FLT Baseline; N=20; 40 animals; ~36 weeks old) at Kennedy Space Center (KSC; 12/9/17). A Ground Control group mimicked the Flight LAR group which was housed at KSC then shipped alive to Novartis Facilities where both the LAR and LAR Ground Control groups were processed (~41 weeks old; 1/16/18). All were anesthetized with isoflurane blood samples were obtained by closed-chest cardiac puncture and the animals were euthanized by exsanguination and thoracotomy. The 20 ISS Terminal mice were anesthetized via intraperitoneal injection of ketamine/xylazine/acepromazine over the course of a four days of dissections (2/6/18 until 2/9/18; 53-56 days after launch; 44 weeks old at time of on-orbit dissections). Blood samples and euthanasia were conducted the same as LAR and Baseline. Following blood draw and hind limb dissection the ISS-terminal animal carcasses were wrapped in aluminum foil placed in a ziploc bag and placed in storage at -80C or colder until return. The ISS-terminal Ground Controls (at KSC) followed the same euthanasia timeline methods and preservation. The final processing of frozen ISS-terminal frozen ISS-terminal Ground Controls and frozen 0-day FLT baseline animals were completed at Houston Methodist Research Institute in Houston TX (5/21/18 until 5/24/18). GeneLab received samples of colon from only sham treated animals (no drug treated animals) from the following groups Flight: LAR (n=10) ISS Terminal (n= 9); Ground Controls: LAR GC (N=8) ISS Terminal GC (N=9) LAR Baseline (n=9) ISS Terminal Baseline (n=9). Total RNA was extracted and sequenced at a target depth of 60 M clusters per sample (ribodepleted paired end 150).

The objective of the Rodent Research-5 (RR-5) study was to evaluate bone loss in mice during spaceflight and to determine if treatment with a modified version of NEL-like molecule-1 (NELL-1) can reduce or prevent bone loss that would otherwise occur during spaceflight. To this end a cohort of forty 30-weeks-old female BALB/cAnNTac mice were flown to the ISS and housed in the Rodent Habitat. Six days after launch half of the mice were treated with NELL-1 (10 mg/kg in 0.3 ml PBS) while the other half were treated with vehicle control (0.3 mls PBS). Fourteen days after launch animals were again treated with NELL-1 or vehicle control as before except that all animals were also injected with the bone marker calcein green (20 mg/kg in 0.1 ml). Injections of vehicle NELL-1 and bone markers were intraperitoneal. After all forty mice on orbit received two treatments; ten control mice and ten experimental mice were randomly selected for live animal return (LAR). At approximately 30 days after launch the twenty LAR mice were transported live back to Earth. Animals were allowed to recover for 30 days in standard habitats before euthanasia via intraperitoneal injection with ketamine/xylazine. During the recovery the animals received another two treatments. GeneLab received RNA later preserved dorsal skin from ten live animal return and ten matching ground control mice. These were from the vehicle control animals only. RNA was extracted libraries generated (stranded ribodepleted) and sequenced (target 60 M clusters at PE 150 bp).