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In vitro maturation (IVM) of oocytes retrieved from ovum pick-up (OPU) or ovarian tissue (OT) is a standard approach for patients with specific conditions where prior hormonal stimulation is contraindicated. However, the developmental competence of oocytes matured in vitro is still inferior to that of oocytes matured in vivo. Capacitation IVM (CAPA-IVM) includes an extra step of pre-maturation culture (PMC) with c-type natriuretic peptide (CNP) as a meiotic arrestor to better synchronize cytoplasmic and nuclear maturity in oocytes by allowing the cytoplasm additional time to acquire essential components critical for optimal competency. This study aims to evaluate the effect of CAPA-IVM on equine oocyte quality and developmental competence. Immature cumulus–oocyte complexes (COCs) were retrieved from slaughterhouse ovaries and matured in vitro either in CAPA-IVM (short 6 h, long 24 h pre-maturation) or standard IVM. Mature oocytes from each group were analyzed for calcium-releasing potential (n = 52) and single-oocyte proteomics (n = 44), and embryo development (n = 229) was assessed after fertilization with piezo-drilled intracytoplasmic sperm injection (ICSI). Genetic analysis of developed blastocysts (n = 41) was performed to detect chromosomal aberrations. Our findings demonstrate that CAPA-IVM of equine COCs yields significantly higher maturation rates than controls. Moreover, short CAPA-IVM with six hours pre-maturation culture showed substantially higher embryo development potential than the control group (20/69 vs. 9/63, respectively). Genetic analysis revealed a high euploidy rate in equine blastocysts regardless of the maturation conditions. Live calcium imaging of the fertilized oocytes demonstrated that the majority of oocytes displayed non-continuous calcium oscillation patterns, irrespective of maturation conditions. Single-oocyte proteomics reveals a comparable proteomic landscape between mature oocytes subjected to short CAPA-IVM and standard IVM. However, we identified four enriched gene sets with positive enrichment scores after short CAPA-IVM, related to cytoskeleton regulation, ribosomal function, and cytosolic components. Our findings indicate that CAPA-IVM holds the potential to improve oocyte quality and competence in horses. However, further fine-tuning of culture conditions would benefit the effective use of these IVM systems. Moreover, given that the mare serves as an excellent model for human reproduction, the molecular trends identified in this study could provide valuable insights for advancing human artificial reproductive technologies.
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; Angel-Velez, Daniel 2
; Araftpoor Emin 3
; Amin Qurratul Ain 2 ; Hedia, Mohamed 4 ; Bühler Marcel 3
; Gevaert Kris 3
; Menten Björn 5 ; Van, Soom Ann 2
; Chuva de Sousa Lopes Susana Marina 6 ; Stoop, Dominic 7 ; De Roo Chloë 7
; Smits Katrien 2
; Heindryckx Björn 1 1 Ghent-Fertility and Stem Cell Team (G-FaST), Department for Reproductive Medicine, Department of Human Structure and Repair, Ghent University Hospital, Corneel Heymanslaan 10, 9000 Ghent, Belgium; [email protected]
2 Department of Internal Medicine, Reproduction and Population Medicine, Ghent University, 9820 Merelbeke, Belgium; [email protected] (D.A.-V.); [email protected] (Q.A.A.); [email protected] (M.H.); [email protected] (A.V.S.); [email protected] (K.S.)
3 VIB-UGent Center for Medical Biotechnology, Vlaams Instituut voor Biotechnologie (VIB), 9052 Ghent, Belgium; [email protected] (E.A.); [email protected] (M.B.); [email protected] (K.G.), Department of Biomolecular Medicine, Ghent University, 9052 Ghent, Belgium
4 Department of Internal Medicine, Reproduction and Population Medicine, Ghent University, 9820 Merelbeke, Belgium; [email protected] (D.A.-V.); [email protected] (Q.A.A.); [email protected] (M.H.); [email protected] (A.V.S.); [email protected] (K.S.), Theriogenology Department, Faculty of Veterinary Medicine, Cairo University, Giza 12211, Egypt
5 Center for Medical Genetics, Ghent University Hospital, 9000 Ghent, Belgium; [email protected]
6 Department of Anatomy and Embryology, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands; [email protected]
7 Department for Reproductive Medicine, Women’s Clinic, Ghent University Hospital, Corneel Heymanslaan 10, 9000 Ghent, Belgium; [email protected] (D.S.); [email protected] (C.D.R.)