Vitrification of Human Oocytes Before or After Rescue-IVM Does not Impair Maturation Kinetics but Induces Meiotic Spindle Alterations

• DOI: 10.1007/s43032-024-01596-7
• Publication Date: 2024-05-21T20:17:32Z
• Authors: Gaëlle Marteil; Aïcha Metchat; Sandra Dollet; Camille Cugnot; Laure Chaput; Bruno Pereira; Anne Sophie Gremeau; Florence Brugnon
• Keywords: Adult; Cryopreservation; 0301 basic medicine; [SDV]Life Sciences [q-bio]; Spindle Apparatus; Vitrification; In Vitro Oocyte Maturation Techniques; Infertility: Original Article; Meiosis; Kinetics; Actin Cytoskeleton; 03 medical and health sciences; Oocytes; Humans; Female

AbstractCryopreservation of in vitro matured oocytes is still considered as an experimental alternative to mature oocyte vitrification after ovarian stimulation. Here, we investigated whether rescue-IVM should be performed before or after vitrification. For this, 101 immature oocytes (germinal vesicle stage) from women undergoing ICSI were used. Oocytes were divided into three groups: freshly in vitro matured oocytes (IVM), freshly in vitro matured oocytes subsequently vitrified (IVM + VIT) and vitrified/warmed GV oocytes then in vitro matured (VIT + IVM). Oocyte maturation rates and kinetics were assessed using time-lapse technology. Spindle dimensions and polarity, chromosome alignment and cytoplasmic F-actin filament length and density were determined using confocal microscopy and quantitative image analyses. No differences in IVM rates (fresh IVM: 63.16% and IVM post-VIT: 59.38%, p = 0.72) and timings (17.73 h in fresh IVM, 17.33 h in IVM post-VIT, p = 0.72) were observed whether IVM is performed freshly or after vitrification. Meiotic spindles were shorter in VIT + IVM (10.47 µm vs 11.23 µm in IVM and 11.40 µm in IVM + VIT, p = 0.012 and p = 0.043) and wider in IVM + VIT (9.37 µm vs 8.12 µm in IVM and 8.16 µm VIT + IVM, p = 0.027 and p = 0.026). The length-to-width ratio was lower in vitrified groups (IVM + VIT: 1.19 and VIT + IVM: 1.26) compared to IVM (1.38), p = 0.013 and p = 0.014. No differences in multipolar spindle and chromosome misalignment occurrence and cytoplasmic F-actin filament length and density were observed between groups. Our results suggest vitrification before or after rescue-IVM does not seem to impair maturation rates and kinetics parameters but induces meiotic spindle alterations.