Elucidating the mechanisms underlying the long-term effects of mouse embryo vitrification — ASN Events
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  3. Elucidating the mechanisms underlying the long-term effects of mouse embryo vitrification

Elucidating the mechanisms underlying the long-term effects of mouse embryo vitrification (#477)

Yui Maruhashi 1 , Kenji Momozawa 2 , Satoshi Kishigami 1
  1. University of Yamanashi, Kofu, YAMANASHI, Japan
  2. University of Kitasato, Towada, AOMORI, Japan

[Background]

Embryo vitrification, the standard cryopreservation method in assisted reproductive technology, has been associated with increased birth weight and impaired glucose metabolism in offspring, suggesting lifelong effects of preimplantation cryopreservation. However, the underlying mechanisms remain unclear. Since altered ribosome biogenesis during embryogenesis has been implicated in developmental programming, this study investigated whether vitrification induces long-term effects through changes in nucleolar morphology and ribosome biogenesis.

 

[Methods]

IVF-derived blastocysts were assigned to either a vitrification group or a No vitrification group, in which embryos were exposed to vitrification and warming solutions without freezing. After embryo transfer, offspring were evaluated for birth weight, birth rate, postnatal growth, and blood glucose levels. Ribosome biogenesis was quantified in 4-cell embryos by Y10b immunostaining. Nucleolar morphology was analyzed using NOPP140 immunostaining after each vitrification/warming step. Embryos with a single large nucleolus were classified as single nucleolus (SN), whereas those with multiple nucleoli were classified as multiple nucleoli (MN).

 

[Results]

Vitrification significantly increased birth weight and elevated blood glucose levels after high-fat diet feeding. In contrast, offspring from the No vitrification group showed normal birth weight and glucose metabolism comparable to fresh controls. Vitrified 4-cell embryos exhibited significantly reduced ribosome biogenesis. Vitrification increased the proportion of SN-type embryos, while exposure to vitrification solutions alone also increased SN formation. During warming, NOPP140 transiently dispersed and subsequently reassembled.

 

[Conclusions]

The transient dispersion and reassembly of NOPP140 during warming suggest that freezing and warming alter nucleolar organization, resulting in reduced ribosome biogenesis. These alterations may contribute to increased birth weight and impaired glucose metabolism in adulthood.