Tissue Engineering and Human Regenerative Therapies in Space: Benefits for Earth and Opportunities for Long Term Extra Terrestrial Exploration
On Earth gravity is constant and although the precise value depends upon location, the standard value of acceleration due to gravity is 9.81ms 2. This is referred to as 1g. In space astronauts experience microgravity (mG) of approximately 1x10 6ms 2 and on the International Space Station (ISS) astronauts float in space as they are in free fall because for any spacecraft to stay in Earth orbit, it must move at almost exactly the right speed so that the curve of downward acceleration matches the curvature of the Earth. This means that the ISS is an ideal laboratory [1] for studying the effects of mG on living systems to investigate growth and development at both the cellular level, in cell co culture and in complex cellular systems where scaffolds may be required to build architecture and shape that is unconstrained by gravity as is the case in an Earth bound laboratory. The deleterious effects of living and working in mG on astronaut physiology and psychology have been extensively reviewed [2 9] As of May 21st 2019, 571 people have travelled into space [10] spending from Alan Shepherd's 15min flight on board Freedom 7 in 1961 to Valerei Polyakov's 437d 18h flight on the Mir space station in 1995. The length of time that astronauts have lived in mG has varied widely and it is principally since the launch of the ISS, that long duration missions (LDMs) of >3mo have become the norm.