Kusakabe Hirokazu
Department of Biological Sciences Asahikawa Medical University 2-1-1-1 Midorigaoka-higashi 078-8510 Asahikawa Japan.
Reprod Med Biol. 2011 Jun 1;10(4):199-210. doi: 10.1007/s12522-011-0092-7. eCollection 2011 Dec.
Freeze-drying technology may one day be used to preserve mammalian spermatozoa indefinitely without cryopreservation. Freeze-dried mouse spermatozoa stored below 4°C for up to 1 year have maintained the ability to fertilize oocytes and support normal development. The maximum storage period for spermatozoa increases at lower storage temperatures. Freeze-drying, per se, may reduce the integrity of chromosomes in freeze-dried mouse spermatozoa, but induction of chromosomal damage is suppressed if spermatozoa are incubated with divalent cation chelating agents prior to freeze-drying. Nevertheless, chromosomal damage does accumulate in spermatozoa stored at temperatures above 4°C. Currently, no established methods or strategies can prevent or reduce damage accumulation, and damage accumulation during storage is a serious obstacle to advances in freeze-drying technology. Chromosomal integrity of freeze-dried human spermatozoa have roughly background levels of chromosomal damage after storage at 4°C for 1 month, but whether these spermatozoa can produce healthy newborns is unknown. The safety of using freeze-dried human spermatozoa must be evaluated based on the risks of heritable chromosome and DNA damage that accumulates during storage.
冷冻干燥技术或许有一天可用于无限期保存哺乳动物精子而无需冷冻保存。在4°C以下储存长达1年的冷冻干燥小鼠精子仍保持使卵母细胞受精并支持正常发育的能力。精子的最长储存期在较低储存温度下会延长。冷冻干燥本身可能会降低冷冻干燥小鼠精子中染色体的完整性，但如果精子在冷冻干燥前与二价阳离子螯合剂一起孵育，染色体损伤的诱导会受到抑制。然而，在4°C以上储存的精子中染色体损伤确实会累积。目前，尚无既定方法或策略能够预防或减少损伤累积，而储存期间的损伤累积是冷冻干燥技术进步的严重障碍。冷冻干燥的人类精子在4°C储存1个月后，其染色体完整性大致处于染色体损伤的背景水平，但这些精子能否产生健康的新生儿尚不清楚。必须基于储存期间累积的可遗传染色体和DNA损伤风险来评估使用冷冻干燥人类精子的安全性。
