[Ed. note May 2020: Report submitted by TRISH to Task Book in March 2020; covers reporting as of October 2019.]
The original Aims of this project were to: 1) use mice with humanized hematopoiesis to define changes in radiation/stress blood biomarkers in response to mission-relevant doses of simulated space radiation; 2) use the innovative Human-Microbial Cross-Talk human gut-on-a-chip model (HuMiX) to perform studies defining the effects of mission-relevant doses of simulated space radiation on the human GI tract; 3) validate the ability of nanolipoprotein particles (NLP) loaded with curcumin to serve as an effective countermeasure against the effects of simulated space radiation in both the human hematopoietic and GI models; and 4) assess the suitability of curcumin-NLPs as space radiation countermeasures.
During this second year of funding, we have made significant progress towards achieving these goals. During this time, we have:
• Performed H+, 56Fe ion, 16O, gamma-ray, and simplified 5-ion GCR simulator irradiations on both wild-type mice, as requested by TRISH, to provide an in vivo comparator/validation of the in vitro HuMiX human gut-on-a-chip system, and on NSG mice whose hematopoietic systems were first humanized by repopulation with human hematopoietic stem cells (HSC) isolated from the bone marrow of healthy, astronaut-age donors.
• Collected tissues (at multiple times post-IR) and are analyzing GI system, blood for biomarker identification by omics, and hematopoietic system for lineage alterations and DNA damage.
• Found marked histological alterations in small intestine in response to protons and iron ions.
• Discovered that exposure to Mars mission-relevant doses of protons, iron ions, and oxygen ions leads to disruption of the epithelial barrier of the small intestine, as assessed by immunofluorescent staining for Claudin-3.
• Humanized the hematopoietic system of the 1st cohort of 72 NSG mice, installed RFI-tracking p-Chips, and irradiated these mice during NSRL-18C. All mice have now been sacrificed and tissues are being analyzed.
• Switched back to NSG mice (in lieu of NSG-SG3) as the SG3 provided higher short-term engraftment at the cost of long-term repopulation.
• Humanized 84 NSG mice and irradiated during NSRL-19A.
• Irradiated 96 wild-type C57Bl/6 mice during NSRL-19B, as detailed in bullet #1 above, have collected serum and all major tissues, which are currently being analyzed by both immunohistochemistry and multi-omics approaches to define the effects that SEP and GCR radiation exert on the various tissues/organ systems of the body and the ability of our curcumin-laden NLPs to protect against these effects.
• Miniaturized and optimized the HuMix gut-on-a-chip platform to enable its use in the NSRL beamline and have exposed this new optimized system to various ions during NSRL-19A and NSRL-19B.
• Have now shown that the presence of representative species from the microbiome in the HuMiX system appears to provide some degree of protection against the deleterious effects of space radiation. Further studies are now underway to define the mechanistic basis for these observations.
• Designed, formulated, and began testing curcumin-loaded NLPs for their ability to provide radioprotection in vivo in normal/wildtype mice and in NSG mice with humanized hematopoietic systems (NSRL runs 18C, 19A, and 19B).
• Shown cNLPs can mediate protection against SEP and GCR radiation in vivo, at omics level.
• We have shown that the cNLPs provide markedly better protection against all varieties of ions tested than simply giving curcumin in DMSO, using human fibroblasts.
• Have generated a wealth of data on the cellular/molecular pathways that are altered by both SEP and GCR radiation and the impact that cNLPs (and DMSO (dimethyl sulfoxide)-curcumin)) have on these alterations.
• We have shown, for the first time ever, that the exposure of mice harboring human hematopoietic systems to GCR radiation (56Fe ions, thus far; other ions now being tested) leads to enlargement of the spleens to roughly 30 times the normal size (in several mice; not all). Immunohistology exam by clinical hematopathologists have preliminary concluded this is due to induction of human hematological malignancy, as we observed in our prior studies in which human HSC were exposed to these same ions in vitro and then used to repopulate NSG mice. Needless to say, extensive analyses are underway to define the nature of the malignancy.
Our progress to-date has enabled us to begin rigorously testing our hypotheses regarding the effects of space radiation (SEP and GCR) on the human hematopoietic and GI systems, and has provided compelling evidence to support our hypothesis that exposure to space radiation at Mars mission-relevant doses produces marked deleterious effects on both of these human systems. These data have also supported our premise that a novel formulation of a readily available dietary supplement (curcumin) may have the ability to serve as an easy to administer countermeasure that can protect astronauts from at least some of the deleterious effects of space radiation during prolonged missions beyond LEO. Our omics work thus far has also begun to shed light on the molecular/biological pathways that are altered within multiple tissues as a result of exposure of a living organism to gamma-ray radiation and to simulated SEP and GCR radiation, and it is beginning to provide mechanistic clues regarding the means by which curcumin-NLPs mediate their protective effects. Our newly formulated HuMiX chip is performing exceptionally well, and it has begun providing a wealth of information (the first of its kind) on the response of the human GI tract to space radiation and the role played by the gut microbiota in this response.