MALDI-MSI: biomarker discovery for radiation exposures

Once outside of the Earth’s atmosphere astronauts are exposed to two main types of radiation, galactic cosmic rays (GCR) and solar energetic particles. GCRs consist of high energy, charged nuclei of elements ranging from H (hydrogen) to Fe (iron). High energy, charged nuclei of H (protons) are the major component of GCRs whereas approximately 1% of GCRs are larger ions with charges greater than 2+, which are referred to as ions of high (H) atomic number (Z) and energy (E) or HZE ions. Solar energetic particles which occur during solar particle events (SPE) are dominantly protons. Due to the differences in radiation type, dose-rate and energy that astronauts experience compared to radiation encountered on Earth, relatively little is known about the biological effects of exposure during manned space missions. Additionally, much of the current models used to calculate exposure risk are based on extrapolated data obtained on Earth. Increased risk of cancer, CNS disease and cataracts are real-life issues faced by astronauts. Radioactive material has also been used for decades in industry, medicine and weapons of mass destruction. Radiation exposure (accidental or deliberate) as well as radiation therapy used to treat lung cancers often results in radiation-induced lung injury (pneumonitis and fibrosis), which can be fatal . The need for medical countermeasures (MCM) for treatment or mitigation in the event of accidental or intentional radiation exposures is evident. In order to develop MCMs, a clearer understanding of the mechanisms of action by which radiation induces tissue/organ damage is needed, as currently these mechanisms remain incompletely understood. What is evident through the literature in both space radiation and terrestrial radiation studies is that oxidative stress/damage plays a central role in pathologies, and many of the countermeasures evaluated to date have been antioxidants. The identification of biomarkers for radiation damage/syndromes will not only enable the development and evaluation of MCMs, but also aid in identifying biological readouts that will allow for efficient diagnosis following exposures, which may be vital for survival.