Prolonged exposure to space conditions may induce skin thinning and cause profound alterations in the hair growth cycle according to a study in three mice published online in the first issue of npj Microgravity. The 'astromice' spent 91 days in weightlessness, which is the longest duration of any non-human animal in space.
Despite being the largest organ of the human body, responsible for multiple functions including thermal regulation, sensing touch and protection against pathogens and harmful environmental conditions such as radiation, skin has not received much interest in space research. Astronauts have previously described skin dryness and itching after spending time in space, making the skin more susceptible to scratches and irritation.
Betty Nusgens and colleagues investigated the impact of prolonged exposure to extreme space conditions on mouse skin physiology. Six mice were delivered to the ISS by the shuttle Discovery in the Mice Drawer System (MDS), a payload designed for long duration rodent research in space. Skin specimens were collected shortly after landing from the three surviving mice for analysis. An exact replica of the experiment in the MDS was performed on the ground.
Alterations affecting the dermal, hair follicles and muscular compartments of the skin were observed in the astromice, as compared to mice on the ground, with hair follicles being in the active growth (anagen) phase while they should have been in the rest (telogen) phase. These alterations in the skin of mice suggest that the skin of astronauts may also be affected by detrimental changes during long trips in space, however the small sample size has limited the interpretation of this data.