Mitochondrial DNA Copy Number in Cleavage Stage Human Embryos-Impact on Infertility Outcome

Area of Science:

• Reproductive Medicine
• Molecular Biology
• Genetics

Background:

• Mitochondrial DNA (mtDNA) plays a crucial role in cellular energy production and has been implicated in various aspects of human reproduction.
• Understanding the relationship between mtDNA content and early embryonic development is essential for improving IVF outcomes.
• Previous studies suggest potential links between mtDNA and embryo viability, but conclusive evidence is lacking.

Purpose of the Study:

• To investigate the correlation between mitochondrial DNA (mtDNA) content in cleavage-stage embryos and their developmental potential.
• To determine if mtDNA copy number can serve as a biomarker for embryo aneuploidy and implantation success.

Main Methods:

• A retrospective case-control study involving 69 couples undergoing IVF.
• Blastomere biopsy from 314 cleavage-stage embryos (day-3 post-fertilization).
• Low-pass next-generation sequencing (NGS) for aneuploidy detection and mtDNA copy number quantification.
• Calculation of mtDNA copy number by dividing mtDNA reads by nuclear genome reads.

Main Results:

• A significantly higher mtDNA copy number was observed in aneuploid embryos compared to euploid embryos (p < 0.004).
• No statistically significant differences in mtDNA content were found concerning embryo morphology (p = 0.09), sex (p = 0.16), maternal age (p = 0.14), or implantation ability (p = 0.18).
• The mean mtDNA ratio was 6.3 ± 7.5 in aneuploid embryos versus 7.1 ± 5.8 in euploid embryos.

Conclusions:

• While mtDNA content is higher in aneuploid embryos, it is not currently a reliable biomarker for predicting developmental potential at the cleavage stage.
• Further research is needed to explore both quantitative and qualitative aspects of mtDNA in relation to human reproduction.
• The study highlights the complexity of mitochondrial function in early human embryogenesis.