Effects of duration of cryo-storage of mouse oocytes on cryo-survival, fertilization and embryonic development following vitrification

Abstract

Purpose To investigate the effects of cryo-storage duration in liquid nitrogen on oocyte cryo-survival, fertilization and embryonic development following vitrification and warming. Methods Mature mouse oocytes were vitrified with McGill Cryoleaf and stored in liquid nitrogen for a period of 8-10 days, 90-92 days and 180-182 days, respectively. After warming, the survived oocytes were inseminated by intracytoplasmic sperm injection (ICSI) and cultured for 120 h. The rates of oocyte cryo-survival, cleavage and embryonic development were compared. Result(s)The oocyte cryo-survival rate declined following cryo-storage duration for 180-182 days (90.4±7.9%) compared to that of the other two groups (97.4±3.0% and 98.0± 3.3%). The fertilization rate in the group of 180-182 days (66.6±22.0%) was also significantly reduced (P<0.05) compared with the groups of 8-10 days (92.2±10.8%) and 90-92 days (94.7±9.1%). In addition, the number of embryos developed to the blastocyst stage declined significantly (P<0.05) following long cryo-storage duration (72.1± 8.2%, 25.2±3.8% and 5.5±13.6%, respectively). Conclusion(s) The cryo-survival, fertilization rate and embryonic development of mouse oocytes are affected significantly, in an adverse manner, by the cryo-storage duration in liquid nitrogen.

Blastocyst transfer after aseptic vitrification of zygotes: an approach to overcome an impaired uterine environment

“…Although it is generally assumed that thermally driven reactions do not occur in cells at À196°C, it has been reported that, in the case of radiation of an LN 2 /oxygen mixture, a synthesis of oxygen radicals resulting from ozone formation and decomposition cannot be excluded and is even enhanced by the catalytic effect of nitrogen. A recent publication reports that mouse oocytes show impaired survival, fertilization rates and embryonic development after prolonged contact with LN 2 (Yan et al, 2011). These findings are of special interest as the biological sample in the open devices commonly used is constantly exposed to LN 2 since the plug is inserted into the outer straw in the LN 2 bath.…”

“…the constant exposure to toxic low-molecular-weight compounds, still remain if the devices are not hermetically closed (Yan et al, 2011). Although the probability of contamination in LN 2 is still being discussed, this risk is important and indicates that the storage system, especially for long-term storage conditions, should be revised.…”

Vitrification, an efficient cryopreservation procedure but still rising some debates

“…It is commonly admitted in the field of thermodynamic cryobiology that once the glass is formed, it can be aged. 40.0 versus 38.5% after 6 years: NS). In addition, no increase in the malformation rate over time was observed.…”

“…Although, it is generally assumed that thermally driven reactions do not occur in cells at -196°C, it has been reported that in the case of radiation of an LN 2 /oxygen mixture a synthesis of oxygen radicals resulting from ozone formation and decomposition cannot be excluded and is even enhanced by the catalytic effect of nitrogen. Mouse oocytes show impaired survival, fertilization rates and embryonic development after prolonged contact with LN 2 (40). (3,7,9,26,43).…”

Cryopreservation of Hematopoietic and Non-Hematopoietic Stem Cells – A Review for the Clinician

“…Hence, alternative methods for crypreservation of hESC were explored. The vitrification technique is for long in use for cryopreservation of embryos and ooctyes in veterinary and human application (Yan et al, 2011). Vitrification represents the direct transformation of a substance into a glass like state without the formation of ice crystals (M. Ojovan, n d).…”