Cryopreservation of human failed-matured oocytes followed by in vitro maturation: vitrification is superior to the slow freezing method

Reproductive Biology and Endocrinology

Research

Ping Zhou¹  Yu Liu¹  Qiong Xing¹  Yunxia Cao¹  ZhiGuo Zhang² 

[1] Reproductive Medicine Centre, Department of Obstetrics and Gynecology, First Affiliated Hospital of Anhui Medical University, The People's Republic of China;Reproductive Medicine Centre, Department of Obstetrics and Gynecology, First Affiliated Hospital of Anhui Medical University, The People's Republic of China;Anhui Provincial Key Laboratory of Population Health and Aristogenics, the People's Republic of China;

关键词: cryopreservation of human failed-matured oocytes;    slow-freezing;    vitrification;    survival rate;    in vitro;    fertilization;    development rates;   

DOI  :  10.1186/1477-7827-9-156

 received in 2011-08-12, accepted in 2011-12-12,  发布年份 2011

来源: Springer

【 摘 要 】

BackgroundOocyte cryopreservation is an important method used in a number of human fertility circumstances. Here, we compared the survival, in vitro maturation, fertilization, and early embryonic development rates of frozen-thawed human immature oocytes using two different cryopreservation methods.MethodsA total of 454 failed-matured oocytes [germinal vesicle (GV) and metaphase I (MI) stages] were collected from 135 patients (mean age 33.84 +/- 5.0 y) who underwent intracytoplasmic sperm injection (ICSI) cycles between February 2009 and December 2009 and randomly divided into a slow freezing group [1.5 mol/L-1, 2-propanediol (PROH) + 0.2 mol/l sucrose] and vitrification group [20% PROH + 20% ethylene glycol (EG) + 0.5 mol/l sucrose].ResultsThe vitrification protocol yielded a better survival rate than the slow freezing protocol at each maturation stage assessed. Regardless of the maturation stage (GV + MI), the slow freezing protocol had a significantly lower survival rate than the vitrification protocol (p < 0.001). In addition, a significant difference was found in the survival rates between GV and MI oocytes regardless of the protocol used (90.1 vs. 64.7%, respectively; p < 0.01). We also found that the maturation rates of GV and MI oocytes from the slow freezing and vitrification groups were 16.7 vs. 24.4% and 50.8 vs. 55.4%, respectively. Regardless of the protocol used, the GV oocytes had significantly lower viability than MI oocytes after 36 h of in vitro maturation (21.2 vs. 54.0%, respectively; p < 0.01). In addition, the GV and MI oocytes from the slow freezing group had a markedly lower maturation rate than those from the vitrification group (33.6 vs. 43.1%, respectively), but no statistical difference was found between the two groups (P > 0.05). For the GV-matured oocytes, no fertilized eggs were obtained in the slow-freezing group, while a 19.0% (4/21) fertilization rate was observed in the vitrification group. For the MI-matured oocytes, fertilization rates for the slow freezing and vitrified groups were 36% and 61.1%, respectively, but no significant difference was found between the two groups (PIn the Methods section in the MS, all procedures were compliant with ethical guidelines, i.e. approved by the Ethical Committee of our university and Informed Consent signed by each patient. > 0.05). In the GV vitrification group, no embryo formed; however, in the MI slow freezing group, 12 oocytes were fertilized, but only two achieved cleavage and were subsequently blocked at the 2-cell stage. In the MI vitrification group, a total of 22 embryos were obtained, five of which developed to the blastocyst stage.ConclusionsVitrification is superior to the slow freezing method in terms of the survival and developmental rates for the cryopreservation of human failed-matured oocytes. In addition, GV oocytes appeared to be more resistant than MI oocytes to the low temperature and cryoprotectant used during cryopreservation.

【 授权许可】

Unknown   
© Zhang et al; licensee BioMed Central Ltd. 2011. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.