Liquid nitrogen vapor is comparable to liquid nitrogen for storage of cryopreserved human sperm Evidence from the characteristics of post thaw human sperm

Capsule:
Liquid nitrogen (LN2) vapor was comparable to LN2 with respect to post-thaw sperm characteristics, and LN2 vapor may substitute for LN2 for the long-term storage of human sperm.

Authors:
Jingmei Hu, M.D., Shidou Zhao, Ph.D., Chengyan Xu, Ph.D., Lin Zhang, M.D., Shaoming Lu, Ph.D., Linlin Cui, Ph.D., Jinlong Ma, Ph.D., Zi-Jiang Chen, Ph.D.

Volume 104, Issue 5, Pages 1253-1257

Abstract:

Objective:
To compare the differences in the characteristics of post-thaw human sperm after storage in either liquid nitrogen (LN2; −196°C) or LN2 vapor (−167°C).

Design:
Experimental study.

Setting:
University hospital.

Patient(s):
Thirty healthy volunteers who agreed to donate their normal semen samples for infertility or research were included in the study.

Intervention(s):
Semen samples (n = 30) were divided into eight aliquots and frozen. Four aliquots of each human semen sample were stored in LN2 (−196°C), and the other four aliquots were stored in LN2 vapor (−167°C). After 1, 3, 6, or 12 months, samples were thawed and analyzed.

Main Outcome Measure(s):
The motility was evaluated by the manual counting method. The viability was estimated by eosin staining. The morphology was analyzed by Diff-Quik staining. The sperm DNA integrity was determined with acridine orange fluorescent staining, and acrosin activity was assayed by the modified Kennedy method.

Result(s):
The characteristics of post-thaw human sperm, including motility, viability, morphology, DNA integrity, and acrosin activity, showed no significant difference between LN2 and LN2 vapor storage for the different time periods.

Conclusion(s):
LN2 vapor was comparable to LN2 in post-thaw sperm characteristics, suggesting that LN2 vapor may be substituted for LN2 for the long-term storage of human sperm.

  • Jason M. Franasiak

    This is very good phase I data. Do the authors have any experience with or are there any ongoing trials to assess the difference in fertilization potential between the two methods? Perhaps splitting a specimen and then using the thawed specimen to fertilize a split cohort of mature oocytes?

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