A new preliminary study has found that microgravity appears to have little or no effect on the viability of human sperm. This is not only interesting but also shows that it should be possible to transport and store male gametes in space.
This will allow for the possibility of space-based sperm banks that will be essential if mankind is to ever colonize other worlds like Mars.
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What was the study trying to discover?
The micro-gravity effects of space on adult human beings have been widely studied. Its effects on things like the cardiovascular, muscular, neurological and skeletal system are broadly well understood, but little was known about its effects on human gametes, like sperm.
"Some studies suggest a significant decrease in the motility of human fresh sperm samples," said Dr. Montserrat Boada from Dexeus Women's Health in Barcelona.
'[But] nothing has been reported on the possible effects of gravitational differences on frozen human gametes, in which state they would be transported from Earth to space." she continued.
How did they test microgravity effects on human sperm?
The recent study was conducted using a small aerobatic training aircraft (CAP10) which is able to provide short-duration hypogravity exposure. By conducting 20 parabolic maneuvers, each providing around 8 seconds of microgravity, researchers were able to study the effects on sperm motility.
During these periods, researchers conducted a series of standard fertility tests like concentration, motility, vitality, morphology and DNA fragmentation.
The study used frozen, rather than fresh sperm as radiation tends to have known effects on fresh sperm.
"Radiation impairs the quality and viability of human sperm," Dr. Broada explained, "[And] these effects are expected to be greater on fresh sperm than on frozen samples, which are cryopreserved in special cryostraws and transported in cryotanks. So our first step was to investigate gravity conditions and frozen sperm samples. Our best option will be to perform the experiment using real spaceflight, but access is very limited." she added.
What did they find?
The researchers found that the micro-gravity environment made little or no difference whatsoever to control sperm when compared to Earth's gravity.
Dr. Boada herself said that there was 100% concordance in DNA fragmentation rate and vitality, and 90% concordance in sperm concentration and motility. These are minor differences and she added that this is "more probably related to [the] heterogeneity of the sperm sample than to the effect of exposure to different gravity conditions".
While the study's results are interesting, Dr. Broada is quick to point out that it is just a preliminary study. The research group now hopes to validate the results with larger sperm samples, longer microgravity exposure, and even the use of fresh sperm.
"But we do need to know," Dr. Broada added: "If the number of space missions increases in the coming years, and are of longer duration, it is important to study the effects of long-term human exposure to space in order to face them. It's not unreasonable to start thinking about the possibility of reproduction beyond the Earth."
The original study was presented at the European Society of Human Reproduction and Embryology (ESHRE)'s 35th Annual Meeting in Vienna.