Single-Embryo RNA Sequencing Reveals Transcriptomic Alterations in Blastocysts Derived From IVM or Vitrified Oocytes

Area of Science:

• Reproductive Biology
• Developmental Biology
• Genomics

Background:

• In vitro production (IVP) of bovine embryos shows lower developmental competence than in vivo-derived embryos.
• Oocyte cryopreservation (vitrification) further exacerbates the disparity in embryo quality.
• Understanding the molecular basis of reduced embryo quality is crucial for improving assisted reproductive technologies.

Purpose of the Study:

• To investigate the transcriptomic impact of in vitro maturation (IVM) and vitrification on bovine blastocyst quality.
• To identify molecular differences between in vivo-derived, IVF, and vitrified-IVF bovine blastocysts.

Main Methods:

• Analysis of Day 7 bovine blastocysts from three groups: in vivo control, IVF (fresh oocytes), and V_IVF (vitrified-thawed oocytes).
• Whole-blastocyst transcriptome profiling using single-embryo RNA sequencing (SUPeR-seq).
• Analysis of differentially expressed messenger RNAs (mRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs).

Main Results:

• Significantly reduced developmental competence in the V_IVF group (11.8%) compared to IVF (41.5%) and in vivo controls.
• Identification of numerous differentially expressed mRNAs, lncRNAs, and circRNAs in IVF and V_IVF groups versus controls.
• Altered expression of genes involved in oxidative phosphorylation, lysosome activity, chromatin organization, Hedgehog signaling, and stem cell pluripotency.

Conclusions:

• Oocyte vitrification combined with IVM significantly impairs bovine blastocyst development and transcriptomic integrity.
• Disruptions span mRNA, lncRNA, and circRNA layers, indicating multi-layered regulatory circuit dysregulation.
• Findings provide insights into the molecular mechanisms underlying reduced embryo quality in assisted reproduction.