<p>This study examined the effects of the stress of space, specifically low earth orbit, on hematopoietic stem and progenitor cells (HSPCs) that maintain lifelong hematopoiesis and immune responses. Enriched CD34+ HSPCs were derived from 7 astronauts before, during and after 10 and 21-day ISS missions on the International Space Station. The samples were used as input to whole transcriptome sequencing by bulk RNA-Seq performed at The Scripps Research Institute Next Generation Sequencing Core on Illumina NextSeq 2000 sequencer and single cell RNA-Seq performed at The Salk Institute for Biological Studies on Illumina NovaSeq X Plus sequencer. Subsequent expression, RNA editing, and retrotransposon analyses were performed to assess HSPC and immune subpopulation survival dynamics. Overall, these analyses revealed space-associated stem cell hallmarks of aging (SASHA), including spaceflight dependent alterations in HSPC survival and self-renewal, ADAR1, telomere maintenance, mobilization and cell cycle gene expression, combined with space-induced clonal hematopoietic mutations, APOBEC3C activation and retrotransposon deregulation to warrant countermeasure development to enable long-duration spaceflight. </p><p>Post-spaceflight analysis revealed increased C-to-T and clonal hematopoiesis-associated mutations, repetitive element and base deaminase deregulation, decreased telomere maintenance gene expression, and decreased self-renewal capacity compared to ground controls. These results demonstrate the space-associated aging effects in HSPCs after month-long exposure to LEO, providing insights into utilizing the LEO environment to model space-accelerated aging and other age-related malignancies.</p>

Space Associated Stem Cell Hallmarks of Aging in Astronauts