Faculty of Life and Environmental Science, University of Yamanashi, Kofu 400-8510, Japan.
Advanced Biotechnology Center, University of Yamanashi, Kofu 400-8510, Japan.
J Reprod Dev. 2022 Aug 1;68(4):262-270. doi: 10.1262/jrd.2022-048. Epub 2022 Jun 7.
Freeze-dried sperm (FD sperm) are of great value because they can be stored at room temperature for long periods of time, However, the birth rate of offspring derived from FD sperm is low and the step in the freeze-drying process particularly responsible for low offspring production remains unknown. In this study, we determined whether the drying process was responsible for the low success rate of offspring by producing vacuum-dried sperm (VD sperm), using mouse spermatozoa dried in a vacuum without being frozen. Transfer of embryos fertilized with VD sperm to recipients resulted in the production of several successful offspring. However, the success rate was slightly lower than that of FD sperm. The volume, temperature, and viscosity of the medium were optimized to improve the birth rate. The results obtained from a comet assay indicated that decreasing the drying rate reduced the extent of DNA damage in VD sperm. Furthermore, even though the rate of blastocyst formation increased upon fertilization with VD sperm, full-term development was not improved. Analysis of chromosomal damage at the two-cell stage through an abnormal chromosome segregation (ACS) assay revealed that reduction in the drying rate failed to prevent chromosomal damage. These results indicate that the lower birth rate of offspring from FD sperm may result from the drying process rather than the freezing process.
冻干精子（FD 精子）具有很大的价值，因为它们可以在室温下长时间储存。然而，来自 FD 精子的后代出生率较低，导致这种低出生率的冻干过程中的具体步骤尚不清楚。在这项研究中，我们通过使用在真空下干燥而不冷冻的小鼠精子来产生真空干燥精子（VD 精子），从而确定干燥过程是否是导致后代成功率低的原因。将用 VD 精子受精的胚胎转移到受体中，成功产下了几窝后代。然而，成功率略低于 FD 精子。优化了介质的体积、温度和粘度，以提高出生率。彗星分析的结果表明，降低干燥速率可以减少 VD 精子中的 DNA 损伤程度。此外，尽管用 VD 精子受精后囊胚形成率增加，但足月发育并未得到改善。通过异常染色体分离（ACS）检测分析在两细胞期的染色体损伤表明，降低干燥速率并不能防止染色体损伤。这些结果表明，FD 精子后代出生率较低可能是由于干燥过程而不是冷冻过程造成的。
