Introduction

Galactic Cosmic Radiation (GCR) poses one of the most significant health risks for astronauts on long-duration missions beyond Earth’s protective magnetosphere, with the cardiovascular system being particularly vulnerable. Previous research identified a specific signature of circulating microRNAs (miRNAs)—small molecules that regulate gene expression—that changes in response to spaceflight. This study investigates whether therapeutically inhibiting a key trio of these miRNAs can act as a countermeasure, protecting human vascular tissue from the damaging effects of simulated deep space radiation.

Research Objective

The primary goals of this research were to:

  • Determine if inhibiting three specific miRNAs (miR-16-5p, miR-125b-5p, and let-7a-5p) could rescue 3D human microvessel cultures from simulated GCR damage.
  • Identify the key biological pathways, including DNA repair, inflammation, and mitochondrial function, that are modulated by this miRNA-inhibiting treatment.
  • Validate the clinical relevance of these miRNA targets and their associated gene pathways using transcriptomic data from astronauts on the NASA Twin Study, Inspiration4, and JAXA missions.

Key Findings

  • Treatment with antagomirs (miRNA inhibitors) targeting the three miRNAs completely prevented microvessel collapse and restored angiogenesis (new vessel formation) in 3D cell cultures exposed to 0.5 Gy of simulated GCR.
  • The countermeasure significantly reduced the number of DNA double-strand break (DSB) repair foci in irradiated cells, returning them to levels comparable to unirradiated controls. This indicates a more efficient DNA repair mechanism or initial protection from damage.
  • Transcriptomic analysis revealed the treatment reversed GCR-induced inflammation, suppressing key pro-inflammatory pathways such as TNF-alpha and IL-6 signaling.
  • The antagomir cocktail rescued mitochondrial function, reversing the negative effects of radiation on critical energy-producing pathways like oxidative phosphorylation (OXPHOS).
  • Analysis of data from flown astronauts confirmed that a set of 21 key genes regulated by these miRNAs are dysregulated during spaceflight, demonstrating the direct relevance of this countermeasure to human space travel.

Methodology

  • Organisms/Subjects: The study primarily used 3D human microvessel cultures derived from Human Umbilical Vein Endothelial Cells (HUVECs). It was supplemented with miRNA-sequencing data from C57BL/6 mice and validated with re-analysis of publicly available transcriptomic data from human astronauts.
  • Experimental Conditions: Ground-based cell cultures were exposed to 0.5 Gy of simplified simulated Galactic Cosmic Radiation (GCR) at the NASA Space Radiation Laboratory, a dose approximating a mission to Mars.
  • Key Techniques: A multi-omics approach was employed, including 3D cell culture, bulk RNA-sequencing, miRNA-sequencing, immunocytochemistry to visualize DNA damage, and advanced bioinformatics analyses (GSEA, WGCNA) to identify affected pathways.

Importance for Space Missions

This study provides a strong proof-of-concept for a novel pharmacological countermeasure to mitigate a primary health risk of deep-space exploration: radiation-induced cardiovascular damage. The development of this antagomir cocktail into a therapeutic could directly protect astronaut health on missions to the Moon and Mars. By precisely targeting key regulatory molecules, this strategy offers a targeted approach to enhance cellular resilience, reduce long-term disease risk, and ensure crew health and performance during extended missions.

Knowledge Gaps & Future Research

While highly promising, this research highlights several areas for future investigation:

  • The in vivo safety, efficacy, and potential long-term side effects of the antagomir treatment must be thoroughly tested in animal models before considering human application.
  • The optimal delivery mechanism (e.g., injection, oral), dosage, and timing of the countermeasure for astronauts needs to be determined.
  • Further studies are required to understand how this countermeasure interacts with other spaceflight stressors, particularly microgravity, which also impacts the cardiovascular system.

Results

This research provides compelling evidence that inhibiting a specific trio of spaceflight-associated miRNAs protects human vascular cells from the damaging effects of deep space radiation. By demonstrating a clear mechanism of action—reducing DNA damage, inflammation, and mitochondrial dysfunction—and correlating the target genes with data from flown astronauts, this study establishes a robust foundation for developing a new class of countermeasures essential for enabling safe, long-duration human missions beyond low-Earth orbit.

Data Visualization