Microgravity effects on frozen human sperm samples

M. Boada, A. Perez-Poch, M. Ballester, S. García-Monclús, D. V. González, S. García, P. N. Barri & A. Veiga

Women’s Health Dexeus, Department of Obstetrics, Gynaecology and Reproduction, Hospital Universitari Dexeus, Avinguda Carles III 71-75, 08028, Barcelona, Spain; Universitat Politècnica de Catalunya, UPC BarcelonaTech, EEBE Campus Diagonal-Besòs, C. E. Maristany 16, 08019, Barcelona, Spain; Aeroclub Barcelona-Sabadell, Sabadell Airport, Carretera de Bellaterra s/n, 08205 Sabadell, Barcelona, Spain; Women’s Health Dexeus, Unit of Biostatistics, Avinguda Carles III 71-75, 08028, Barcelona, Spain; Barcelona Stem Cell Bank, Centre of Regenerative Medicine in Barcelona, Hospital Duran i Reynals, Gran Via de l’Hospitalet 199, 08908 Hospitalet de Llobregat, Barcelona, Spain.

Abstract:

Purpose: Microgravity has severe effects on cellular and molecular structures as well as on metabolic interactions. The aim of this study is to investigate the effects of microgravity (μg) exposure on human frozen sperm samples.

Methods: Sibling samples from 15 normozoospermic healthy donors were frozen using glycerol as cryoprotectant and analyzed under microgravity and ground conditions. Microgravity was obtained by parabolic flights using a CAP10B plane. The plane executed 20 parabolic maneuvers with a mean of 8.5 s of microgravity for each parabola.

Results: Frozen sperm samples preserved in cryostraws and stored in a secure and specific nitrogen vapor cryoshipper do not suffer significant alterations after μg exposure. Comparing the study group (μg) and the control group (1 g), similar results were obtained in the main parameters studied: sperm motility (M/ml) 13.72 ± 12.57 vs 13.03 ± 12.13 (− 0.69 95% CI [− 2.9; 1.52]), progressive a + b sperm motility (%) 21.83 ± 11.69 vs 22.54 ± 12.83 (0.03 95% CI [− 0.08; 0.15]), sperm vitality (%) 46.42 ± 10.81 vs 44.62 ± 9.34 (− 0.04 95% CI [− 0.13; 0.05]), morphologically normal spermatozoa (%) 7.03 ± 2.61 vs 8.09 ± 3.61 (0.12 95% CI [0.01; 0.24]), DNA sperm fragmentation by SCD (%) 13.33 ± 5.12 vs 13.88 ± 6.14 (0.03 95% CI [− 0.09; 0.16]), and apoptotic spermatozoa by MACS (%) 15.47 ± 15.04 vs 23.80 ± 23.63 (− 0.20 95% CI [− 0.66; 1.05]).

Conclusion: The lack of differences obtained between frozen samples exposed to μg and those maintained in ground conditions provides the possibility of considering the safe transport of human male gametes to space. Nevertheless, further research is needed to validate the results and to consider the possibility of creating a human sperm bank outside the Earth.

Journal of Assisted Reproduction and Genetics – DOI: 10.1007/s10815-020-01877-5
Received: 16 April 2020 / Accepted: 29 June 2020 / Published: 18 July 2020