title: The effect of two cryopreservation methods on human sperm DNA damage.
abstract: Several methods are currently available for selection when conducting sperm cryopreservation, however, these methods might cause different degrees of damage on sperm DNA. The aim of the this study is to compare the effects of storage at -80 °C (in ultra-low temperature refrigerator) and at -196 °C (in liquid nitrogen) on sperm DNA damage, thus to provide a reference for choosing the right method according to different aims. We randomly collected 28 semen samples from college students of Chongqing city. The samples stored at -80 °C were neat semen samples and the samples stored at -196 °C were mixed with additional cryoprotectants. Each sample was subjected to two freezing-thawing cycles, and the sperm DNA damage levels of fresh and thawed samples were measured by single cell gel electrophoresis (SCGE) and sperm chromatin structure assay (SCSA). Both SCGE and SCSA assays showed cryopreservation induced significant damage to sperm DNA. However, storage at -196 °C lead to more severe damage to sperm DNA than storage at -80 °C measured by SCSA. Sperm DNA damage increased simultaneously with the higher frequency of freezing-thawing cycles. We concluded that storage of neat semen samples at -80 °C had milder damage to sperm DNA than storage at -196 °C mixed with cryoprotectants. To avoid additional sperm DNA damage, repeated freezing and thawing should be prevented.
authors.affiliation: School of Public Health, University of Ningxia Medical, Yinchuan, 750004, People's Republic of China; Institute of Toxicology, College of Preventive Medicine, University of Third Military Medical, Chongqing, 400038, People's Republic of China.
authors.forename: Taixiu
authors.initials: T
authors.lastname: Liu
authors.affiliation: School of Public Health, University of Ningxia Medical, Yinchuan, 750004, People's Republic of China; Institute of Toxicology, College of Preventive Medicine, University of Third Military Medical, Chongqing, 400038, People's Republic of China.
authors.forename: Jianfang
authors.initials: J
authors.lastname: Gao
authors.affiliation: Institute of Toxicology, College of Preventive Medicine, University of Third Military Medical, Chongqing, 400038, People's Republic of China.
authors.forename: Niya
authors.initials: N
authors.lastname: Zhou
authors.affiliation: Institute of Toxicology, College of Preventive Medicine, University of Third Military Medical, Chongqing, 400038, People's Republic of China.
authors.forename: Min
authors.initials: M
authors.lastname: Mo
authors.affiliation: Institute of Toxicology, College of Preventive Medicine, University of Third Military Medical, Chongqing, 400038, People's Republic of China.
authors.forename: Xiaogang
authors.initials: X
authors.lastname: Wang
authors.affiliation: Institute of Toxicology, College of Preventive Medicine, University of Third Military Medical, Chongqing, 400038, People's Republic of China.
authors.forename: Xi
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Institute of Toxicology, College of Preventive Medicine, University of Third Military Medical, Chongqing, 400038, People's Republic of China.
authors.forename: Huan
authors.initials: H
authors.lastname: Yang
authors.affiliation: Institute of Toxicology, College of Preventive Medicine, University of Third Military Medical, Chongqing, 400038, People's Republic of China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Chen
authors.affiliation: Institute of Toxicology, College of Preventive Medicine, University of Third Military Medical, Chongqing, 400038, People's Republic of China.
authors.forename: Lin
authors.initials: L
authors.lastname: Ao
authors.affiliation: Institute of Toxicology, College of Preventive Medicine, University of Third Military Medical, Chongqing, 400038, People's Republic of China.
authors.forename: Jinyi
authors.initials: J
authors.lastname: Liu
authors.affiliation: Institute of Toxicology, College of Preventive Medicine, University of Third Military Medical, Chongqing, 400038, People's Republic of China. Electronic address: zhihongcui_4@126.com.
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Cui
authors.affiliation: Institute of Toxicology, College of Preventive Medicine, University of Third Military Medical, Chongqing, 400038, People's Republic of China; School of Public Health, University of Ningxia Medical, Yinchuan, 750004, People's Republic of China. Electronic address: caojia1962@126.com.
authors.forename: Jia
authors.initials: J
authors.lastname: Cao
mesh_terms: D015925:Cryopreservation / Q000379:methods*; D003451:Cryoprotective Agents / Q000494:pharmacology; D004249:DNA Damage; D005615:Freezing; D006801:Humans; D008297:Male; D012662:Semen Preservation / Q000379:methods*; D013081:Sperm Motility / Q000187:drug effects; D013094:Spermatozoa / Q000187:drug effects / Q000502:physiology
chemical_list: D003451:Cryoprotective Agents
keywords: Cryopreservation; DNA damage; SCGE; SCSA; Sperm