TY - JOUR
T1 - Human ovarian aging is characterized by oxidative damage and mitochondrial dysfunction
AU - Smits, Myrthe A. J.
AU - Schomakers, Bauke V.
AU - van Weeghel, Michel
AU - Wever, Eric J. M.
AU - Wüst, Rob C. I.
AU - Dijk, Frederike
AU - Janssens, Georges E.
AU - Goddijn, Mariëtte
AU - Mastenbroek, Sebastiaan
AU - Houtkooper, Riekelt H.
AU - Hamer, Geert
N1 - Funding Information: The authors acknowledge the Center for Reproductive Medicine Fertility Laboratory for providing the GV and MI oocytes and cumulus cells for research; PALGA: Dutch Pathology Registry for using human ovarian biopsies (); Milou Kleijn and Stella Dorrestein for their help optimizing the immunofluorescence assays; Cindy Korver and Saskia van Daalen for running the immunofluorescence assays for ROS-induced damage; Wendy Noort for her help with deconvolution microscopy; Ronald Wanders for critically reading the manuscript; and the Amsterdam Reproduction & Development research institute for financial support (grant number V.000296). Funding Information: The study was funded by the Amsterdam UMC. Publisher Copyright: © The Author(s) 2023. Published by Oxford University Press on behalf of European Society of Human Reproduction and Embryology.
PY - 2023/11/1
Y1 - 2023/11/1
N2 - STUDY QUESTION: Are human ovarian aging and the age-related female fertility decline caused by oxidative stress and mitochondrial dysfunction in oocytes? SUMMARY ANSWER: We found oxidative damage in oocytes of advanced maternal age, even at the primordial follicle stage, and confirmed mitochondrial dysfunction in such oocytes, which likely resulted in the use of alternative energy sources. WHAT IS KNOWN ALREADY: Signs of reactive oxygen species-induced damage and mitochondrial dysfunction have been observed in maturing follicles, and even in early stages of embryogenesis. However, although recent evidence indicates that also primordial follicles have metabolically active mitochondria, it is still often assumed that these follicles avoid oxidative phosphorylation to prevent oxidative damage in dictyate arrested oocytes. Data on the influence of ovarian aging on oocyte metabolism and mitochondrial function are still limited. STUDY DESIGN, SIZE, DURATION: A set of 39 formalin-fixed and paraffin-embedded ovarian tissue biopsies were divided into different age groups and used for immunofluorescence analysis of oxidative phosphorylation activity and oxidative damage to proteins, lipids, and DNA. Additionally, 150 immature oocytes (90 germinal vesicle oocytes and 60 metaphase I oocytes) and 15 cumulus cell samples were divided into different age groups and used for targeted metabolomics and lipidomics analysis. PARTICIPANTS/MATERIALS, SETTING, METHODS: Ovarian tissues used for immunofluorescence microscopy were collected through PALGA, the nationwide network, and registry of histo- and cytopathology in The Netherlands. Comprehensive metabolomics and lipidomics were performed by liquid–liquid extraction and full-scan mass spectrometry, using oocytes and cumulus cells of women undergoing ICSI treatment based on male or tubal factor infertility, or fertility preservation for non-medical reasons. MAIN RESULTS AND THE ROLE OF CHANCE: Immunofluorescence imaging on human ovarian tissue indicated oxidative damage by protein and lipid (per)oxidation already at the primordial follicle stage. Metabolomics and lipidomics analysis of oocytes and cumulus cells in advanced maternal-age groups demonstrated a shift in the glutathione-to-oxiglutathione ratio and depletion of phospholipids. Age-related changes in polar metabolites suggested a decrease in mitochondrial function, as demonstrated by NAD+, purine, and pyrimidine depletion, while glycolysis substrates and glutamine accumulated, with age. Oocytes from women of advanced maternal age appeared to use alternative energy sources like glycolysis and the adenosine salvage pathway, and possibly ATP which showed increased production in cumulus cells. LIMITATIONS, REASONS FOR CAUTION: The immature oocytes used in this study were all subjected to ovarian stimulation with high doses of follicle-stimulating hormones, which might have concealed some age-related differences. WIDER IMPLICATIONS OF THE FINDINGS: Further studies on how to improve mitochondrial function, or lower oxidative damage, in oocytes from women of advanced maternal age, for instance by supplementation of NAD+ precursors to promote mitochondrial biogenesis, are warranted. In addition, supplementing the embryo medium of advanced maternal-age embryos with such compounds could be a treatment option worth exploring.
AB - STUDY QUESTION: Are human ovarian aging and the age-related female fertility decline caused by oxidative stress and mitochondrial dysfunction in oocytes? SUMMARY ANSWER: We found oxidative damage in oocytes of advanced maternal age, even at the primordial follicle stage, and confirmed mitochondrial dysfunction in such oocytes, which likely resulted in the use of alternative energy sources. WHAT IS KNOWN ALREADY: Signs of reactive oxygen species-induced damage and mitochondrial dysfunction have been observed in maturing follicles, and even in early stages of embryogenesis. However, although recent evidence indicates that also primordial follicles have metabolically active mitochondria, it is still often assumed that these follicles avoid oxidative phosphorylation to prevent oxidative damage in dictyate arrested oocytes. Data on the influence of ovarian aging on oocyte metabolism and mitochondrial function are still limited. STUDY DESIGN, SIZE, DURATION: A set of 39 formalin-fixed and paraffin-embedded ovarian tissue biopsies were divided into different age groups and used for immunofluorescence analysis of oxidative phosphorylation activity and oxidative damage to proteins, lipids, and DNA. Additionally, 150 immature oocytes (90 germinal vesicle oocytes and 60 metaphase I oocytes) and 15 cumulus cell samples were divided into different age groups and used for targeted metabolomics and lipidomics analysis. PARTICIPANTS/MATERIALS, SETTING, METHODS: Ovarian tissues used for immunofluorescence microscopy were collected through PALGA, the nationwide network, and registry of histo- and cytopathology in The Netherlands. Comprehensive metabolomics and lipidomics were performed by liquid–liquid extraction and full-scan mass spectrometry, using oocytes and cumulus cells of women undergoing ICSI treatment based on male or tubal factor infertility, or fertility preservation for non-medical reasons. MAIN RESULTS AND THE ROLE OF CHANCE: Immunofluorescence imaging on human ovarian tissue indicated oxidative damage by protein and lipid (per)oxidation already at the primordial follicle stage. Metabolomics and lipidomics analysis of oocytes and cumulus cells in advanced maternal-age groups demonstrated a shift in the glutathione-to-oxiglutathione ratio and depletion of phospholipids. Age-related changes in polar metabolites suggested a decrease in mitochondrial function, as demonstrated by NAD+, purine, and pyrimidine depletion, while glycolysis substrates and glutamine accumulated, with age. Oocytes from women of advanced maternal age appeared to use alternative energy sources like glycolysis and the adenosine salvage pathway, and possibly ATP which showed increased production in cumulus cells. LIMITATIONS, REASONS FOR CAUTION: The immature oocytes used in this study were all subjected to ovarian stimulation with high doses of follicle-stimulating hormones, which might have concealed some age-related differences. WIDER IMPLICATIONS OF THE FINDINGS: Further studies on how to improve mitochondrial function, or lower oxidative damage, in oocytes from women of advanced maternal age, for instance by supplementation of NAD+ precursors to promote mitochondrial biogenesis, are warranted. In addition, supplementing the embryo medium of advanced maternal-age embryos with such compounds could be a treatment option worth exploring.
KW - NAD
KW - mitochondrial dysfunction
KW - oocyte quality
KW - ovarian ageing
KW - oxidative damage
UR - http://www.scopus.com/inward/record.url?scp=85176496352&partnerID=8YFLogxK
U2 - https://doi.org/10.1093/humrep/dead177
DO - https://doi.org/10.1093/humrep/dead177
M3 - Article
C2 - 37671592
SN - 0268-1161
VL - 38
SP - 2208
EP - 2220
JO - Human reproduction (Oxford, England)
JF - Human reproduction (Oxford, England)
IS - 11
ER -