PROtection MEdiated by Antioxidant NanoTEchnOlogy Against Neuronal Damage in Space (PROMETEO, Antioxidant Protection)
Oxidative stress (OS) is the mechanism at the base of many deleterious effects of spaceflight, involving exposure to microgravity (MG, also termed µg) and cosmic radiation (CR), and it is inherent to the genesis of several pathological conditions on Earth (among which Crohn's and Parkinson's diseases). Arising from the unbalanced production and elimination of pro-oxidant chemical species, OS implies short- and long-term alterations of targets from the molecular up to the whole organism level. The central nervous system (CNS) is the most critical target of OS, requiring special antioxidant protection with the increasing duration of spaceflights and in view of interplanetary travels. MG- and CR-induced cognitive and motor alterations, which are well known to progressively deteriorate human performance in space and can have life-threatening consequences on astronauts, can indeed be ascribed to dopamine dysregulation following OS generated during spaceflight This project proposes the use of polydopamine-based nanoparticles (NPs) to provide 1) antioxidant protection and 2) catecholaminergic support to neurons undergoing exposure to altered gravity and radiation. The focus is on neuronal cells involved in cognitive and motor functions both in space, where any behavioural impairments pose significant risks to manned expeditions, and on Earth, where dopaminergic neuron loss underlying Parkinson's disease (PD) progression still requires effective contrast. This project in particular aims at exploring the connection between spaceflight and OS, by discriminating the effects of MG from those of CR, and at providing nanotechnology countermeasures to short- and potentially long-term alterations of the CNS due to spaceflight-induced reduction/oxidation (redox) reaction imbalance. This project also aspires at providing relevant evidence and therapeutic tools for the treatment of neurodegenerative conditions like PD on Earth. Overall design: To assess potentially protective effects of antioxidant nanoparticles on neuron-like cells during spaceflight, cell cultures were prepared on ground in triplicate for each experimental class, and they were then integrated in fluidic bioreactors qualified for spaceflight. Cell culture medium was either added or not with nanoparticles. Cell cultures were uploaded to the International Space Station (ISS) and integrated in both static and dynamic slots of Kubik incubator. Static slots determined exposure of cell cultures to real microgravity with cosmic radiation. Dynamic slots instead determined exposure of cell cultures to simulated Earth gravity with cosmic radiation. The experiment was conducted on board the ISS for four days. Then, the cell cultures were rinsed, fixed and cold stowed until return to the home laboratory. Spaceflight cell cultures were de-integrated from fluidic bioreactors and prepared for analysis by total RNA extraction/purification. Control cell cultures were set on ground in triplicate for each experimental class, and they were exposed to the thermal profile of spaceflight samples. Cells were kept under static or dynamic culture conditions. Static conditions determined exposure to real Earth gravity without cosmic radiation. Dynamic conditions were obtained by rotation on random positioning machine, and they determined exposure to simulated microgravity without cosmic radiation. Cell cultures were prepared for analysis, and RNA sequencing was conducted on all samples.