Vitrification of Mouse Blastocyst / 대한산부인과학회잡지

OBJECTIVE: The aim of this study was to compare the survival and developmental rate of two vitrification solutions for the vitrification of mouse expanded blastocysts. METHODS: Mouse embryos were obtained at 2 cell stage and cultured to expanded blastocyst stage in Human Tubal Fluid (HTF) medium supplemented with 10% serum substitute supplement (SSS). The vitrification solutions used were EFS40 and VS. EFS40 consisted of 40% ethylene glycol, 18% ficoll, and 0.5 M sucrose while VS consisted of 20% ethylene glycol, 20% DMSO, and 10% 1,3-butanediol diluted in Dulbecco's phosphate-buffered saline (DPBS) medium supplemented with 10% calf serum (CS). Toxicity was tested by exposing expanded blastocysts to vitrification solution. The vitrification procedure used for EFS40 was performed in three steps, after which they were warmed in 5 steps with 0.5 M sucrose. VS was performed in two steps, after which they were warmed with 1.0 M trehalose. Recovery, survival and hatching rate per expanded blastocysts recovered were compared between two groups. RESULTS: In toxicity test, survival and hatching rate of EFS40 group were 95% and 100%, respectively. In contrast, survival and hatching rate of VS group were 100% and 87.5%, respectively. After vitrification and warming in solution, recovery rate for EFS40 group was 73.7% whereas recovery rate for VS group was 66.5%. After 24 h culture, survival and hatching rate were 80.5% and 20.7% for EFS40 and 66% and 0% for VS group, respectively. After 48 h culture, survival and hatching rate were 69% and 33.3% for EFS40 and 58.3% and 1.9% for VS group, respectively. Survival and hatching rate in EFS40 group were significantly higher than those found in VS group. CONCLUSION: The EFS40 solution was better than VS solution for vitrification of mouse expanded blastocysts.

The Study on Vitrification and Ultrarapid Thawing of Human Embryonic Stem Cells / 대한불임학회지

OBJECTIVE: This study was carried out to establish the effectiveness of the vitrification method and the optimal cryoprotectants in the cryopreservation of human embryonic stem cells (ESC). MATERIALS AND METHODS: Human ESC clumps established at Seoul National University Hospital (SNUhES 1) were cryopreserved with the vitrification method using the EM grid. EDS and EFS40 were used as vitrification solutions. RESULTS: Between the EDS and EFS40 groups, there was no significant difference in the recovery rate after cryopreservation of human ESC. The formation rates of ESC colonies in the vitrified groups were significantly lower than those in the control ESC group (p<0.05, p<0.05). In addition, the formation rate of ESC colonies in the EDS group was significantly higher than that in the EFS40 group (p<0.05). The ESC colonies in the vitrified groups were significantly smaller after culture duration of 2 and 4 days, respectively, compared with the control ESC group (p<0.01, p<0.05). However, these effects could be reduced to nonsignificant level by the additional culture of ESC colonies. The vitrified human ESC retained the properties of pluripotent cells, including the expression of cell surface markers for the undifferentiated cells such as alkaline phosphatase and SSEA-4 (stage-specific embryonic antigen-4), and the expression of transcription factor Oct-4 (octamer-binding transcription factor-4), and the normal karyotype. CONCLUSION: The vitrification method using the EM grid and EDS solution was confirmed to be very effective for the cryopreservation of human ESC.