Cryopreservation of human embryos using ethylene glycol in controlled slow freezing.
BACKGROUND
Ethylene glycol (EG) has been successfully used as a cryoprotectant for vitrification of mammalian formula embryos (including human embryos) due to its low formula weight and high permeation into cells compared with other cryoprotectants, including propylene glycol (PROH). This study was carried out to evaluate the permeation and toxicity of EG and to investigate the effects of its use in a slow-freezing protocol on post-thaw development of mouse embryos and on pregnancy outcome of frozen human embryos.


METHODS
Spare human embryos after embryo transfer were cryopreserved using 1.5 mol/l EG or PROH using a slow-freezing protocol which had been tested previously in mouse experiments.


RESULTS
The post-thaw survival rate of human embryos in the EG group (80.6%) was significantly higher than that in the PROH group (65.2%, P < 0.05). The implantation and clinical pregnancy rates of human embryos in the EG group (20.3 and 46.9%) were significantly higher than those in the PROH group (7.5 and 24.6%, P < 0.05).


CONCLUSIONS
Ethylene glycol may be a good substitute for PROH to cryopreserve human embryos using a slow-freezing protocol.
Chi
Hee-Jun
HJ
IVF Center, Hanna Women's Clinic and Department of Animal Sciences, Kon-Kuk University, Seoul, Korea. hanna129@hanmail.net
Koo
Jung-Jin
JJ
Kim
Moon-Young
MY
Joo
Jin-Young
JY
Chang
Sang-Sik
SS
Chung
Kil-Saeng
KS
D000328:Adult; D000818:Animals; D015925:Cryopreservation / Q000379:methods*; D003451:Cryoprotective Agents / Q000493:pharmacokinetics / Q000633:toxicity; D010064:Embryo Implantation; D004624:Embryo Transfer; D004622:Embryo, Mammalian / Q000187:drug effects / Q000502:physiology; D019855:Ethylene Glycol / Q000493:pharmacokinetics / Q000633:toxicity; D005260:Female; D006801:Humans; D051379:Mice; D011247:Pregnancy; D011256:Pregnancy Outcome; D018873:Pregnancy Rate; D011446:Prospective Studies; D013997:Time Factors; D014022:Tissue Survival
D003451:Cryoprotective Agents; D019855:Ethylene Glycol