Mitochondrial DNA copy number of cumulus cells is not linked to embryo implantation in good prognosis IVF patients

Research question: Could the mitochondrial DNA (mtDNA) copy number of cumulus cells be used as a biomarker of the potential of embryo implantation in good prognosis IVF patients? Design: A prospective cohort study on good prognosis IVF patients from a large reproductive medicine centre. A total of 392 embryos from 61 cycles (including 31 implanted and 30 non-implanted cycles) were enrolled in the study. The corresponding cumulus cell mtDNA copy number of embryos was tested by real-time quantitative polymerase chain reaction. The corresponding cumulus cell mtDNA copy numbers were compared between implanted and non-implanted embryos and also compared between high quality and poor quality embryos. Then, a mitochondrial function assay including mitochondrial membrane potentials, concentration of reactive oxygen species (ROS) and ATP content of the corresponding cumulus cells were compared between high quality and poor quality embryos to verify the above experimental findings . Results: For the same population, the mean cumulus cell mtDNA copy numbers for implanted and non-implanted embryos were 255.61 +/- 81.02 and 254.50 +/- 73.29 (P = 0.47), and those for high quality and poor quality embryos were 266.02 +/- 98.56 and 295.71 +/- 70.64 (P = 0.99), respectively. There was no significant difference in cumulus cell mtDNA copy number between implanted and non-implanted embryos or between high quality and poor quality embryos. The mitochondrial membrane potential, ROS levels and ATP content of the corresponding cumulus cells did not differ significantly between high quality and poor quality groups. Conclusions: Measurement of cumulus cell mtDNA copy number might not provide any advantage to embryo prioritization in good prognosis IVF patients. Any suggested link between cumulus cell mtDNA copy number and embryo implantation requires further validation.