Abstract
Although the body’s immune system is altered during spaceflight, the effects of microgravity (μG) on tumor growth and carcinogenesis are, as yet, unknown. To assess tumor proliferation and its effects on the immune system, we used a hind-limb unloading (HU) murine model to simulate μG during spaceflight. HU mice demonstrated significantly increased tumor growth, metastasis to the lung, and greater splenic and thymic atrophy compared with mice in constant orthostatic suspension and standard housing controls. In addition, mice undergoing temporary loading during HU (2 h per day) demonstrated no difference in cancer progression and immune organ atrophy compared with controls. Our findings suggest that temporary loading can prevent cancer progression and immune organ atrophy induced by HU. Further space experiment studies are warranted to elucidate the precise effects of μG on systemic immunity and cancer progression.
Highlights
To date, over 500 astronauts have traveled to space, with long-term stays of 6 months to 1 year in the International Space Station (ISS) likely to become possible
The tteemmpoproarryarlyoaldoinagdidnugrindgurHinUg(2HhUpe(r2dhayp)e(rTLd)a; y) (TL) group demonstrated 32.1% fewer metastatic nodules compared with hind-limb unloading (HU), and there were no statistically significant differences in the number of metastases between the TL
The TL group demonstrated 32.1% fewer metastatic nodules compared with HU, and there were no statistically significant differences in the number of metastases between the and CToLnagnrdoCuopns.gAroluthpos.uAglhthtohuegrhe twheerreewneorestnaotissttaictiasltliycaslliygnsiigfinciafincat ndtidffieffreernecnecsesbbeettwweeeenn tthhee CCoonnaanndd OS groupOsS, thgreonuupsm, btheer onfummebtearstoafsmeseitnastthaseesOSingtrhoeupOSwagsrosuipgnwifiacsansitglnyifliocwanetrlythloawn etrhethoatnhetrhesuostpheernsion groupssus(pFeingsuioren 3g)r.ouApdsd(Fitiigounrael3ly)., Aa dndeigtiaotnivalelyc,oarrneelgaattiiovne cboertrweleaetinonimbemtwueneen oimrgmaunnwe oeirgahnt awnedighcat ncer prograensdsiocannwcearsparolsgoreisdseionntiwfiaesda(lFsoigiudreentAifi1eBd)(.Figure A1B)
Summary
Over 500 astronauts have traveled to space, with long-term stays of 6 months to 1 year in the International Space Station (ISS) likely to become possible. Space radiation, including heavy ions, is one of the main health hazards of spaceflight. Exposure to space radiation on long-duration and exploration spaceflights may lead to an increased risk of cancer [1,2], tissue degeneration, and development of cataracts [3,4], and may affect the central nervous system [5,6,7], cardiovascular system [8], and immune functions [9]. ETmhoenssetrraetesdulttos oscucgugredsut rtihnagtsipmacmefulingehtsaynsdtepmersaibsterdruartinogns cmaounstehds by streosrsboitraslasspsaocceifaltiegdhtws i[t1h7,s2p2–a2c4e].trTahvesleshreosuulldtsbseuigngcelustdtehdatwihmemnuensetimsyasttienmg raibskerfroatriopnasthcoaluosgeidesbsyuch as csatrnecsesor.rs associated with space travel should be included when estimating risk for pathologies such asHcainncde-rl.imb unloading (HU) of rodents was developed in the 1980s to enable the study of mechanHisimnds-,lirmesbpounnlsoeasd, ianngd(HtrUea)tmofenrotsdefnotrsthweasaddveevresloepceodnsineqtuheen1c9e8s0osf tsopaenceaflblieghtht.e Astluthdoyuogfh it is umseecdhatoniisnmvse,srteisgpaotenstehse, aenfdfectrteoatfmweneitgs hfotlretshseneasdsveornsethcoenmseuqsuceunlcoesskoeflestpaalcseyflsigtehmt.
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