Author: Wai I Ho Edited by: Marcia Costa, Jun Hon Pang
Most of us have, since childhood, dreamed to travel to space one day. However, what is the current progress of human space travel? Are we getting any closer to achieving the goal? On February 7th, 2018, SIU London organised an event that highlighted progress in this area, titled “Bridging Frontiers in Space Medicine: Translation Science in Extreme Environments”.
The first speaker was Prof. Thais Russomano, who is a senior lecturer and the deputy director of the master’s degree programme in space physiology and health at the Centre for Human & Applied Physiological Sciences (CHAPS) at King’s College London. She is also a co-founder of Innova Space (Europe) and International Space Medicine Consortium (USA). Her work focuses on space life science and telehealth. Prof. Thais Russomano revealed the medical challenges faced in space missions. It is believed that gravity on Earth has influenced evolution of our anatomy and physiology. In space, in order to adapt to microgravity (very weak gravity in space aircrafts compared to Earth), our anatomy and physiology change. Microgravity affects physiological systems at different rates, including the neurovestibular, cardiovascular, musculoskeletal systems and red blood cells. In the first 72 hours, motion sickness is commonly observed due to a disconnection between the visual and the vestibular system (the latter is dependent on gravity). The blood, which on Earth is mostly on the lower body, moves to the upper body. Although an initial increase in heart size is measured, heart atrophy is observed over time. The rush of blood to the upper body also results in vasodilation, which increases the body core temperature, so astronauts are in a state of constant inflammation. The increase of fluid to the head also causes an increase in CO2 in the brain and may lead to more eye problems. Astronauts stretch between 6 and 8 cm during each space mission, so they suffer from back pain, as well as a decrease in bone mass when they return to Earth. A study has demonstrated that 70% of astronauts have suffered space deconditioning, leading to issues such as cardiac arrhythmias and orthostatic intolerance in each space mission. Besides, there are two main concerns related to space travel- one is radiation that could increase the chance of cancer development, and the other is that social deprivation has an impact on mental health.
To improve living and working conditions, the environment of space shuttles has been transformed to mimic the Earth condition with respect to oxygen concentration, pressure and temperature. In order to improve astronauts’ diet, Prof. Thais Russomano has developed a technique to grow plants in a small centrifuge by using microgravity in space. As poor diets could change astronauts’ microbiota, this could affect the immune system. In order to monitor the immune system through the proliferation of T cells, Prof. Thais Russomano with her team from the Microgravity Centre (MicroG), the first academic and research institution to study Space Life Science in Latin America, has developed a device known as clinostat. To counter the long-term effects of microgravity, other devices have been developed that allow astronauts to exercise in space; one such device is Microanhypothen. Human powered centrifuges that facilitate G force exercises have also been designed. Other medical activities including blood collection or even emergency events such as cardiopulmonary resuscitation (CPR) require innovative device design or novel techniques. For the former, an earlobe arterialised blood collector has also been developed by the Zero-G team of MicroG*. Further, the Evetts-Russomano CPR method has been adapted for extraterrestrial CPR, which overcomes issues with performing chest compressions in microgravity.
*There is an exhibition of the earlobe arterialised blood collector from MicroG centre displayed in Science Museum London, UK permanently.
The second speaker was Prof. Stephen Harridge from the Ageing Research group at King’s (ARK). He conducts research on the ageing of muscles under space flight conditions. Muscles are biological machines converting chemical energy stored in food (carbohydrates & fats) into mechanical work such as heat and strength. It has been suggested that microgravity causes accelerated ageing as shown by deteriorating skeletal muscle, cardiovascular and immune functions. In space, astronauts have less power and force in muscles due to atrophy, which is similar to what happens to an elder. This is likely due to the fact that microgravity reduces the size of muscle fibres, which makes them more glycolytic and oxidative, resulting in atrophy. Ageing is a long-term process causing loss of muscle size and quality. In elders, sarcopenia infiltration of fat and connective tissue in the muscle occurs, but the same does not happen to astronauts in space. Thus, there are some differences between ageing observed on Earth and muscle atrophy resultant from microgravity. Prof. Stephen Harridge suggested that the key to overcome the musculoskeletal issues in both cases, ageing and space travel, is exercising. Although exercising cannot stop the ageing process, it could improve muscle performance by increasing mitochondrial complex protein content. In conclusion, microgravity is a model of accelerated sedentary ageing, as opposed to healthy active ageing, and astronauts are encouraged to perform exercises while travelling to space. In fact, it is mandatory to exercise two hours per day.
“Being physically active (and eating well) is the default position for maintaining good physiological function” - Prof. Stephen Harridge
Our event closed with a panel discussion. One particularly interesting question that was raised was on the use of growth hormone to improve the astronauts’ weightlessness during space flight. However, it is a quite ineffective therapy in muscle growth.Alternatively, using DNA methylation to enhance microgravity adaptation remains a fascinating and challenging area to research in space biology. Another important aspect pointed out is that the subject sample to study all the physiological changes is very small due to the small number of astronauts in the world.