Latent virus reactivation, reduction in the number of immune cells, decreased cell activation and increased sensitivity of astronauts to infections following their return on Earth demonstrate that the immune system is less efficient during space flight. This dysfunction during long-term missions could result in the appearance of opportunistic infections or a decrease in the immuno-surveillance mechanisms that eradicate cancer cells. On the other hand, monitoring of the microbial environment is essential to prevent infectious diseases in space. Therefore, both aspects will have to be monitored continuously during long-term missions in space, using miniature and semi-automated diagnostic systems. In the short term, such equipment will allow the study of the causes of space-related immunodeficiency, developing countermeasures to maintain an optimal immune function and improving our capacity to prevent infectious diseases during space missions. In order to achieve these objectives, a new diagnostic system has been designed to perform a set of biological and immunological assays on board spacecrafts. Through flow cytometric assays and molecular biology analyses, this diagnostic system will improve medical surveillance of astronauts and will be used to test countermeasures aimed at preventing immune deficiency during space missions.
Research Containing: Flow cytometer
Cytogenetic analysis of peripheral blood lymphocytes is the most sensitive and reliable method currently available for in vivo assessment of the biological effects of exposure to radiation and provides the most informative measurement of radiation induced health risks. Data indicates that space missions of a few months or more can induce measureable increases in the yield of chromosome damage in the blood lymphocytes of astronauts that can be used to estimate an organ dose equivalent, and biodosimetry estimates lie within the range expected from physical dosimetry. Space biodosimetry poses some unique challenges compared to terrestrial biological assessments of radiation exposures, but data provides a direct measurement of space radiation damage, which takes into account individual radiosensitivity in the presence of confounding factors such as microgravity and other stress conditions. Moreover if chromosome damage persists in the blood for many years, results can be used for retrospective dose reconstruction. In contrast to physical measurements, which are external to body and require multiple devices to detect all radiation types all of which have poor sensitivity to neutrons, biodosimetry is internal and includes the effects of shielding provided by the body itself plus chromosome damage shows excellent sensitivity to protons, heavy ions, and neutrons. In addition, chromosome damage is reflective of cancer risk and biodosimetry values can therefore be used to validate and develop risk assessment models that can be used to characterize health risk incurred by crewmembers. The current paper presents a review of astronaut biodosimetry data, along with recently derived data on the relative cancer risk estimated using the quantitative approach derived from the European Study Group on Cytogenetic Biomarkers and Health database.