Successful cryopreservation of mouse and human blastocysts using vitrification solution without sucrose and Ficoll

Abstract

Successful cryopreservation of mouse and human blastocysts using vitrification solution without sucrose and Ficoll C.W. Kim1 , D.H. Lee2 , B.S. Joo3,†,∗ , K.S. Lee2,†,∗ 1Department of Obstetrics and Gynecology, Samsung Changwon Hospital, Sungkyunkwan University School of Medicine, Changwon (Republic of Korea) 2Department of Obstetrics and Gynecology, Pusan National University School of Medicine, Busan 49241 (Republic of Korea) 3 Infertility Institute, Pohang Women’s Hospital, Pohang 37754 (Republic of Korea) Summary Purpose of Investigation: This study investigated whether cryopreservation of mouse and human blastocysts using vitrification solutions formulated with or without sucrose and Ficoll affects survival rate and pregnancy outcome. Materials and Methods: Two-cell mouse embryos were retrieved from C57BL/CBA females aged 5 weeks and cultured to the blastocyst stage. Artificial shrinkage of blastocysts was performed by blastocoel fluid aspiration before vitrification and then exposed to and vitrified-warmed in one of four different vitrification solutions: 1) 25% glycerol, 25% ethylene glycol, 20% SSS and PBS without sucrose and Ficoll (G25E25), 2) G25E25 with 0.5 M sucrose (G25E25S0.5), 3) G25E25 with 10 mg/mL Ficoll (G25E25F10), and 4) G25E25 with 0.5 M sucrose and 10mg/mL Ficoll (G25E25S0.5F10). Second, in 435 infertile women undergoing in vitro fertilization and embryo transfer (IVF-ET), artificially shrunken blastocysts were vitrified-warmed either in G25E25 (n = 206) and G25E25S0.5F10 (n = 229). Results: In the mouse series, in vitro survival rates of post-warm blastocysts were 93, 91, 90, and 90% in G25E25, G25E25S0.5, G25E25F10, and G25E25S0.5F10, respectively. No significant differences among four groups were found. In the human series, in vitro survival rates and clinical pregnancy rate of blastocysts vitrified-warmed in G25E25 were 96 and 53.3%, respectively, which were similar to those in G25E25S0.5F10 (92 and 51.9%, respectively). Conclusions: Sucrose- and Ficoll-free vitrification solutions can be successfully cryopreserved mouse and human blastocysts without compromising survival rate and pregnancy outcome. Key words: Blastocyst; Vitrification; Sucrose; Ficoll; Survival; Pregnancy outcome.