Decreased human sperm motility and vitality after fast gravity load changes in a parabolic flight

Abstract

Little is known about the effects of low gravity on human gametes. The aim of this study was to analyze if fresh human sperm samples after fast gravity load changes suffered any detrimental effect in comparison to the splits maintained in Earth’s gravity. Fifteen fresh samples from normozoospermic donors were analyzed. Statistically significant differences in vitality (69.7 ± 9.9 % vs 72.4 ± 9.7 %, [95% CI: 0.002,0.07]); motile sperm concentration (23.7 ± 15.3 M/ml vs 31.5 ± 25.1 M/ml, [95% CI: 1.03,14.65]); grade “a” sperm concentration (8.7 ± 6.5 M/ml vs 11.7 ± 9.9 M/ml, [95% CI: 0.71,5.28]); percentage of progressive motility sperm (30 ± 12.9 % vs 36 ± 14.3 %, [95% CI: 0.10,0.37]) and curvilinear velocity VCL: 45.7 ± 12.8 µm/s vs 47.7 ± 13.3 µm/s, [95% CI: 0.79,3.22]) were observed. No statistical differences were observed in other sperm kinematic parameters, morphology, DNA fragmentation, apoptosis, and oxidative stress. In conclusion, even though it did not result in a total loss, heavy gravity load changes including microgravity causes a significant decrease in sperm vitality and motility suggesting that negative consequences would be even higher if the exposure were longer. The results obtained indicate that further research is really needed before Assisted Reproduction will be considered for the future human reproduction outside the Earth.

Peer Reviewed

Postprint (published version)