Single-cell transcriptomic analysis reveals subtle fluctuations of oocyte cryopreservation on mouse early embryo development.

BACKGROUND

Oocyte cryopreservation is widely used in assisted reproductive technology, but its effects on embryonic development remain a concern. This study aimed to determine whether oocyte cryopreservation induces transcriptional alterations at the early cleavage and blastocyst stages.

METHODS

We performed single-cell RNA sequencing on mouse Metaphase II oocyte and embryos at early/late 1 cell, early/late 2 cell, morula and blastocyst stages derived from cryopreserved (cryo) and fresh (fresh) oocytes. Transcriptomic profiles were compared between the two groups.

RESULTS

Global transcriptomes were highly similar between cryo and fresh blastocysts. Oocyte cryopreservation did not alter the sex ratio or the developmental progression through preimplantation development. In blastocysts, cryopreservation affected only a few individual genes. In both male and female blastocysts, although oocyte cryopreservation increased the proportion of low Xist-expressing cells, it did not disrupt X-linked gene dosage. In the inner cell mass (ICM) of blastocysts, a negative correlation between X-linked gene expression and cell cycle progression was identified, and this negative correlation was more pronounced in trophectoderm (TE) cells. Overall, this stage-dependent coordination remained unperturbed by cryopreservation. CellChat analysis revealed that the signalling interaction strength between ICM and TE also showed no significant changes in the cryo group.

CONCLUSIONS

Oocyte cryopreservation does not severely disrupt overall transcriptional integrity, developmental potency and X-chromosome dosage compensation of embryos, but it may cause subtle molecular changes. These findings highlight the need for continued refinement of cryopreservation methods and further investigation into the sub-acute safety of assisted reproductive technology procedures.