Biphasic CAPA-IVM Improves Equine Oocyte Quality and Subsequent Embryo Development Without Inducing Genetic...

Area of Science:

• Reproductive Biology
• In Vitro Fertilization
• Oocyte Maturation

Background:

• In vitro maturation (IVM) of oocytes is crucial for patients with contraindications for hormonal stimulation.
• Current IVM techniques yield oocytes with suboptimal developmental competence compared to in vivo matured oocytes.
• Capacitation IVM (CAPA-IVM) utilizes pre-maturation culture with c-type natriuretic peptide (CNP) to enhance oocyte synchrony and competency.

Purpose of the Study:

• To evaluate the efficacy of CAPA-IVM in improving equine oocyte quality and developmental competence.
• To compare the outcomes of short (6h) and long (24h) CAPA-IVM protocols against standard IVM.

Main Methods:

• Immature equine cumulus-oocyte complexes (COCs) were matured using standard IVM or CAPA-IVM (6h or 24h pre-maturation).
• Mature oocytes were assessed for calcium-releasing potential, subjected to single-oocyte proteomics, and used for embryo development via intracytoplasmic sperm injection (ICSI).
• Developed blastocysts underwent genetic analysis for chromosomal aberrations.

Main Results:

• CAPA-IVM significantly increased equine oocyte maturation rates compared to controls.
• Short CAPA-IVM (6h) demonstrated superior embryo development potential (20/69) versus standard IVM (9/63).
• Proteomics revealed comparable landscapes but identified enriched gene sets related to cytoskeleton and ribosomal function in short CAPA-IVM oocytes; high euploidy rates were observed in all blastocysts.

Conclusions:

• CAPA-IVM shows promise for enhancing equine oocyte quality and developmental competence.
• Further optimization of CAPA-IVM culture conditions is necessary for maximizing its benefits.
• Findings offer insights into improving human assisted reproductive technologies, using the mare as a model.