Transcriptional profiling of heart tissue from mice flown on the RRRM-2 mission

To assess differences in outcomes due to age, twenty 12 week-old and twenty 29 week-old mice were flown, respectively. To directly assess spaceflight effects, half of the young and old mice (10 old, 10 young) were sacrificed on-orbit after 55-58 days (ISS Terminal, ISS-T), while the other half (10 old, 10 young) were returned live to Earth after 32 days and allowed to recover for 24 days (Live Animal Return, LAR) before sacrifice.

ISS-T and LAR mice were the same age at sacrifice. Both the ISS-T and LAR animals had independent ground controls (GC; 10 mice per group housed in flight hardware in matched environmental conditions), basal controls (BSL; 10 mice per group sacrificed 2 days before launch), and vivarium controls (VIV; 10 mice per group housed within standard vivarium habitats). Thus RRRM-2 included a total of 160 mice.