Cryobiological Characteristics of L-proline in Mammalian Oocyte Cryopreservation

• Published in: Chinese medical journal Vol. 129; no. 16; pp. 1963 - 1968
• Main Authors: Zhang, Lu, Xue, Xu, Yan, Jie, Yan, Li-Ying, Jin, Xiao-Hu, Zhu, Xiao-Hui, He, Zhi-Zhu, Liu, Jing, Li, Rong, Qiao, Jie
• Format: Journal Article
• Language: English
• Published: China Wolters Kluwer - Medknow Publications 20.08.2016; Medknow Publications and Media Pvt. Ltd; Lippincott Williams & Wilkins Ovid Technologies; Department of Obstetrics and Gynecology, Center for Reproductive Medicine, Peking University Third Hospital, Beijing 100191, China; Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproduction, Beijing 100191, China%Beijing Key Laboratory of Cryo-Biomedical Engineering and Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China%Department of Obstetrics and Gynecology, Center for Reproductive Medicine, Peking University Third Hospital, Beijing 100191, China; Key Laboratory of Assisted Reproduction, Ministry of Education, Beijing 100191, China; Medknow Publications & Media Pvt Ltd; Wolters Kluwer
• Subjects: Analysis; Animals; Biotechnology industry; Conflicts of interest; Cryopreservation; Cryopreservation - methods; Cryoprotective Agentant; Mouse Oocyte; Vitrification; Cryoprotective Agents - pharmacology; DNA methylation; Efficiency; Female; Fertilization in Vitro; Gene expression; Hydrogen-Ion Concentration; Laboratory animals; Male; Mice; Oocytes; Oocytes - drug effects; Original; Osmotic Pressure; Proline; Proline - pharmacology; Raman spectroscopy; Spectrum analysis; Spectrum Analysis, Raman; Sucrose; Vitrification; China; Mouse Oocyte; Cryoprotective Agentant; Vitrification
• ISSN: 0366-6999; 2542-5641; 2542-5641
• DOI: 10.4103/0366-6999.187846

Background： L-proline is a natural, nontoxic cryoprotectant that helps cells and tissues to tolerate freezing in a variety of plants and animals. The use of L-proline in mammalian oocyte cryopreservation is rare. In this study, we explored the cryobiological characteristics of L-proline and evaluated its protective effect in mouse oocyte cryopreservation. Methods： The freezing property of L-proline was detected by Raman spectroscopy and osmometer. Mature oocytes obtained from 8-week-old B6D2F 1 mice were vitrified in a solution consisting various concentration of L-proline with a reduced proportion ofdimethyl sulfoxide （DMSO） and ethylene glycol （EG）, comparing with the control group （15% DMSO and 15% EG without L-proline）. The survival rate, 5-methylcytosine （5-mC） expression, fertilization rate, two-cell rate, and blastocyst rate in vitro were assessed by immunofluorescence and in vitro fertilization. Data were analyzed by Chi-square test. Results： L-proline can penetrate the oocyte membrane within 1 min. The osmotic pressure of 2.00 mol/L L-proline mixture is similar to that of the control group. The survival rate of the postthawed oocyte in 2.00 mol/L L-proline combining 7.5% DMSO and 10% EG is significantly higher than that of the control group. There is no difference of 5-mC expression between the L-proline combination groups and control. The fertilization rate, two-cell rate, and blastocyst rate in vitro from oocyte vitrified in 2.00 mol/L L-proline combining 7.5% DMSO and 10% EG solution are similar to that of control. Conclusions： It indicated that an appropriate concentration of L-proline can improve the cryopreservation efficiency of mouse oocytes with low concentrations of DMSO and EG, which may be applicable to human oocyte vitrification.