Citations

Abstract Technological advancements have increased the number of human spaceflights, including the advent of space tourism and deep space travel. The structure and function of the pulmonary system are gravitationally dependent, highlighting the importance of understanding functional changes within the pulmonary system during transient and sustained microgravity exposure. This systematic review and meta-analysis provide an overview of effects of microgravity (0G) on various functional outcome measures of the human lungs relative to Earth gravity (1G). Twenty-eight studies comprising parabolic flights (~20 seconds), short- (≤30 days) and long-duration spaceflight (>30 days) were assessed. Outcome measures reported in 1G (before flight) and 0G (in-flight) were extracted. Fixed effects models showed microgravity caused a reduction in elastic work and carbon dioxide production, and increases in pulmonary diffusion capacity, compliance, and pulmonary capillary blood volume. Despite this, the effect sizes were small and likely have little clinical significance in healthy individuals. However, they could impact space tourists who have lower health requirements for space travel, and those with underlying obstructive respiratory disorders. The results demonstrate how traditional functional pulmonary testing provides essential physiological benchmarks that complement high-throughput data collection methods, enabling an integrated understanding of how molecular changes translate into functional respiratory outcomes in microgravity.

Galactic cosmic ray (GCR) radiation is a major barrier to human space exploration beyond Earth’s magnetic field protection. Mesenchymal stem cells (MSCs) are found in all organs and play a critical role in repair and regeneration of tissue. We engineered bone marrow-derived MSCs and evaluated their response to ionizing radiation exposure. Epidermal growth factor receptor (EGFR) expression by certain types of cancers has been shown to induce radioresistance. In this study, we tested the feasibility of transfecting MSCs to overexpress EGFR (eMSC-EGFR) and their capacity to tolerate and recover from X-ray exposure. Quantitative real-time PCR (qRT-PCR) and immunoblotting results confirmed the efficient transfection of EGFR into MSCs and EGFR protein production. eMSC-EGFR maintained characteristics of human MSCs as outlined by the International Society for Cell & Gene Therapy. Then, engineered MSCs were exposed to various dose rates of X-ray (1–20 Gy) to assess the potential radioprotective role of EGFR overexpression in MSCs. Post-irradiation analysis included evaluation of morphology, cell proliferation, viability, tumorigenic potential, and DNA damage. eMSC-EGFR showed signs of radioresistance compared to naïve MSCs when assessing relative proliferation one week following exposure to 1–8 Gy X-rays, and significantly lower DNA damage content 24 h after exposure to 4 Gy. We establish for the first time the efficient generation of EGFR overexpressing MSCs as a model for enhancing the human body to tolerate and recover from moderate dose radiation injury in long-term manned space travel.