Successful pregnancy following blastocyst cryopreservation using super-cooling ultra-rapid vitrification.
BACKGROUND
Blastocysts were cryopreserved by a new two-step ultra-rapid cooling in super-cooled liquid nitrogen (-205 degrees C).


METHODS
There were 308 mouse blastocysts collected from fertile B6CBF1 mice and 249 human blastocysts collected from 51 couples treated with IVF. The blastocysts were super-cooled by a Vit-Master and cryoloops after treatment in 50 and 100% vitrification solution (VS) for 2 min and 30 s, respectively. The 100% VS was composed of 20% ethylene glycol, 20% dimethylsulphoxide and 0.5 mol/l sucrose in human tubular fluid medium with 20% human serum albumin. The embryos were warmed after treatment in 0.25 and 0.125 mol/l sucrose for 2 and 3 min, respectively. The survival of embryos was observed after re-swell.


RESULTS
The survival rate (SR) and hatching rate (HR) of mouse blastocysts in the super-cooled, the cryosolution-treated and control groups were not significantly different (SR, 87, 95.5 and 100%; HR, 50, 33 and 44.6%, respectively; P>0.05). After 96 super-cooled human blastocysts were warmed, 60 survival blastocysts were transferred into 13 patients. The successful SR and pregnancy rate (PR) for the super-cooled blastocyst group were 77.1% (74 out of 96) and 53.8% (seven out of 13).


CONCLUSIONS
The ultra-rapid vitrification of blastocysts with a successful SR and PR could be used to replace classical slow cooling.
Division of Infertility Clinic, Lee Women's Hospital, Institute of Biochemistry, Chung-Shan Medical University and Department of Obstetrics and Gynecology, Chung-Shan Medical University Hospital, Taichung, Taiwan.
Chun-Chia
CC
Huang
Tsung-Hsien
TH
Lee
Shee-Uan
SU
Chen
Hsiu-Hui
HH
Chen
Tzu-Chun
TC
Cheng
Chung-Hsien
CH
Liu
Yu-Shih
YS
Yang
Maw-Sheng
MS
Lee
D000818:Animals; D001755:Blastocyst; D015925:Cryopreservation / Q000295:instrumentation / Q000379:methods*; D003451:Cryoprotective Agents; D004624:Embryo Transfer; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D011247:Pregnancy; D011256:Pregnancy Outcome; D014021:Tissue Preservation / Q000295:instrumentation / Q000379:methods*
D003451:Cryoprotective Agents