EFFECTS OF ALTERED GRAVITY ON STEM CELL BIOLOGY AND TISSUE REGENERATION IN THE PRESENCE OF CERIUM OXIDE NANOPARTICLES

The gravitational force of 1 g is the oldest environmental factor and life on Earth has adapted perfectly to this nearly constant force. It is well known that isolated cells in culture can sense altered gravity and modify important biological processes such as proliferation and differentiation, cytoskeleton organization and signal transduction responses. Altered gravity also induces reactive oxygen species (ROS) production and cellular oxidative stress with lipid peroxidation and DNA damage and this effect is more pronounced after long-duration space flights and lasts for several weeks after landing. Recently, the use of particles with redox-reactive properties, such as cerium oxide nanoparticles (nanoceria), has been proposed, due to their self-regenerating capability as free radical scavengers to contrast ROS production in altered gravity. With the aim to analyse the effect of altered gravity on stem cell biology and tissue regeneration, as well as to assess the ability of nanoceria to protect a living organism, we exposed planarians (Dugesia japonica), to simulated micro-gravity, reduced gravity paradigm and hyper-gravity in the presence or absence of nanoceria. Preliminary results suggest an influence of hyper-gravity on stem cell determination and a protective activity of nanoceria.