The reality of humans getting reproductive help in space just got a little bit closer.
Scientists in Spain report frozen sperm samples subjected to space-like gravity conditions were as viable as those that remained on Earth, a finding that could eventually lead to sperm banks in space.
The results "open the possibility of safely transporting [sperm] to space and considering the possibility of creating a human sperm bank outside Earth," said Montserrat Boada and her colleagues at Dexeus Women's Health in Barcelona. Boada is chief of its biology section.
For the study, her team analyzed 10 frozen sperm samples from 10 healthy donors. The samples were placed in a small airplane that did 20 aerobatic maneuvers that resulted in 8 seconds of microgravity each time.
Afterward, those sperm were compared to samples that stayed on the ground. Researchers used measurements common to fertility testing, including number of sperm, their activity and DNA damage, among them.
There were no differences between the two groups of samples, according to the study presented Monday at the annual meeting of the European Society of Human Reproduction and Embryology (ESHRE), in Vienna.
Boada noted that the effects of microgravity on the central nervous system, muscles, bones, blood vessels and the heart have been tested in space flight and are well-known. But relatively little is known about how different gravity affects human sperm and eggs, she added.
"Some studies suggest a significant decrease in the motility of human fresh sperm samples, but nothing has been reported on the possible effects of gravitational differences on frozen human [sperm], in which state they would be transported from Earth to space," Boada said in a meeting news release.
This was a preliminary study, and the results need to be confirmed. Boada said that would be followed by studies with more frozen samples, longer periods of microgravity and even fresh sperm.
"We do need to know," she said. "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."
One reason for using frozen sperm in this study was the known effect of radiation on fresh sperm. The longer the flight, the higher the radiation exposure.
"Radiation impairs the quality and viability of human sperm, and these effects are expected to be greater on fresh sperm than on frozen samples," Boada said.
"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 said.
Research presented at meetings is typically considered preliminary until published in a peer-reviewed journal.
The Mayo Clinic has more facts about healthy sperm.