Developing a human organ-on-a-chip system to investigate and measure the effect of microgravity and radiation in space with a focus on NASH development

Abstract

Since humanity made history in 1969 when Neil Amstrong and his crew first set foot on the Moon, most space missions have focused on bringing astronauts to low Earth’s orbit (LEO). It is only now, in the middle of 2022, that we have sent the Artemis I mission to the moon, with the goal of bringing astronauts on board the Artemis III two years from now. In this context, companies like SpaceX have been making the front pages with their announcements of soon-to-be space missions for Mars exploration and colonization. Earth’s atmosphere provides us with protection from high intensity radiation originated in the Sun, but astronauts lack this protection in LEO or beyond. Furthermore, all species on Earth’s surface have evolved in a specific set of conditions. Earth has a gravitational effect that pulls us towards its center, with a force that we measure as 1G (one earth gravity). If humanity aims to further expand in the universe, it is of utmost importance to study the effect that space stressors such as radiation and microgravity will have on human biology. Traditionally, research has been performed taking astronauts as subjects, but the sample size is low and procedures such as biopsies are invasive in nature. Alternatively, rodents have been used as models, but their biological differences to humans impedes the faithful extrapolation of results. Recently, a new technology called “organ-on-a-chip” has been developed. These chips are not electronic chips but are made of glass or other material not toxic to cells that has microscopic channels carved inside them. In these channels, researchers can introduce cells from a specific organ. This chip, with the cells from an organ –for example the liver—can be used to study the response of that organ to certain drugs or stimuli, since it is expected to react on a similar way as the real organ would. When the chip can reliably mimic the behaviour of an organ, we call it a valid “model” of that organ. We propose to send one of these models of a liver to the International Space Station (ISS), where it will be exposed to space stressors, and then bring it back to Earth, where it will be compared to a model that stayed on ground. In this comparison, we will measure the accumulation of fat, formation of scar tissue and inflammation, which are common symptoms of non-alcoholic fatty liver disease (NAFLD). On Earth, this disease is normally related to diet, diabetes, or genetic factors, but it has been suggested that it could happen in space just by exposure to radiation or microgravity. The results that we obtain from this research will open a door to send more models of liver or other organs to space and study the development of different diseases, and potentially find drugs that prevent or attenuate them. This way, we would ensure that the future humans that travel across the universe are protected and can safely reach their destination.