Mitochondrial DNA Levels in Trophectodermal Cells Show No Association with Blastocyst Development and Pregnancy Outcomes

Abstract

Background: In patients undergoing assisted reproduction, levels of mitochondrial DNA (mtDNA) in the trophectodermal cells of the developing blastocyst are suggested to be associated with its ability to implant. However, discrepancies exist regarding the use of mtDNA levels as a reliable biomarker to predict outcomes of assisted reproduction. Aims: The aim of the study is to explore the association of trophectodermal mtDNA levels to determine blastocyst quality, implantation potential of blastocyst and clinical outcomes in couples who have undergone pre-implantation genetic testing for aneuploidy (PGT-A). Study Setting: Private fertility centre. Study Design: Retrospective analysis. Materials and Methods: We analysed mtDNA levels in the trophectodermal cells of 287 blastocysts from 61 couples undergoing PGT-A. The levels of mtDNA were estimated by next-generation sequencing method. mtDNA levels were correlated with maternal age, blastocyst morphology, ploidy status, implantation rates, miscarriage rate and live birth rate. Statistical Analysis Used: Linear regression and one-way ANOVA with Tukey's all column comparison test. Results: The trophectodermal mtDNA levels did not correlate with maternal age. There were no significant differences in their levels in grade 1 and grade 2 blastocysts. No significant differences were seen between mtDNA levels of implanted and non-implanted blastocysts or those blastocysts that resulted in miscarriage or live birth. However, significantly lower amounts of mtDNA were seen in euploid blastocysts as compared to that in aneuploid blastocysts. Conclusion: mtDNA levels in the trophectodermal cells of the blastocyst do not associate with blastocyst quality (grade 1 and grade 2), implantation potential and clinical outcomes but can differentiate between aneuploid and euploid blastocysts. Our study does not support the use of trophectodermal mtDNA levels as a biomarker for blastocyst quality and predictor of clinical outcomes.

Dynamics of Mitochondrial DNA Copy Number and Membrane Potential in Mouse Pre-Implantation Embryos: Responses to Diverse Types of Oxidative Stress

“…A better understanding of mtDNA kinetics in pre-implantation embryos is particularly relevant because the mtDNA copy number has been considered as a potential marker of human embryo quality [ 46 , 47 ]. Associations between the embryo mtDNA copy number and implantation potential have been uncovered in some studies but not others [ 48 , 49 , 50 , 51 , 52 , 53 ]. Importantly, mtDNA is measured in TE biopsies, which our preclinical data confirmed is not necessarily reflective of the mtDNA copy number within the ICM but may be important for successful implantation.…”

Mechanisms of mitochondrial dysfunction in ovarian aging and potential interventions

“…Studies in multiple clinics found that high mtDNA levels in blastocysts were related to aneuploidy embryos and implantation failure ( 216 – 218 ). The latest retrospective investigation analyzed the transfer cycle of frozen single euploid embryos, and the results showed that no correlation was observed between mtDNA content and blastocyst morphology grades or pregnancy outcomes ( 219 , 220 ). Still, lower mtDNA content was associated with delayed blastocyst development ( 219 ).…”

“…Still, lower mtDNA content was associated with delayed blastocyst development ( 219 ). It should be noted that there is currently no consensus on the threshold for the mtDNA copy number of blastocysts, and the accuracy of using mtDNA copy number as a single predictive biomarker for embryo selection and developmental potential remains low ( 216 – 220 ).…”

Blastocyst telomere length predicts successful implantation after frozen-thawed embryo transfer

“…Consequently, studies reported that embryos with mtDNA levels higher than average showed a poor implantation rate ( Diez-Juan et al , 2015 ; Fragouli et al , 2015 ). However, confirmatory studies from other groups failed to validate the initial findings and suggested that mtDNA cannot predict the reproductive potential of embryos ( St John, 2016 ; Treff et al , 2017 ; Ritu et al , 2022 ). Furthermore, a review by Seli has concluded that mtDNA copy number (mtCN) may be used as a biomarker for embryo viability ( Seli, 2016 ).…”