There was no substantive difference between the range of sperm characteristics observed in frozen sperm samples exposed to microgravity and in those maintained in ground conditions, according to a study reported at the 35th Annual Meeting of the European Society of Human Reproduction and Embryology. The study was carried out by Montserrat Boada of Dexeus Women’s Health in Barcelona, Spain, and associates. Microgravity engineers from the Polytechnic University of Barcelona were associated with study.
This, the study said, opened the possibility of safely transporting male gametes to space and of creating a human sperm bank outside the earth.
While the effects of microgravity on the cardiovascular, musculo-skeletal and central nervous systems are well known and tested in space flight, Montserrat Boada pointed out that relatively little was known about the effects of different gravitational environments on human sperm and eggs. “Some studies suggest a significant decrease in the motility of human fresh sperm samples,” she said, “but nothing has been reported on the possible effects of gravitational differences on frozen human gametes, in which state they would be transported to space.”
The study was performed using a small aerobatic training aircraft (CAP10), which can provide short-duration hypogravity exposure, totalling 160 seconds of microgravity. Overall, 10 sperm samples obtained from 10 healthy donors were analysed after exposure to the different microgravities found in space and ground gravity. The sperm analysis comprised the full range of measurements currently performed for fertility testing. According to Montserrat Boada, there was 100 per cent concordance in the DNA fragmentation rate and vitality, and 90 per cent concordance in sperm concentration and motility. These minor differences, she added, “were more probably related to heterogeneity of the sperm sample than to the effect of exposure to different gravity conditions.” This preliminary study will be followed up with validating the results and then move on to larger sperm samples, longer periods of microgravity and even fresh sperm, she said.
Montserrat Boada observed that one reason for using frozen sperm in this study was the known effect of radiation on fresh sperm. “Radiation impairs the quality and viability of human sperm,” she said, “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.”