Vitrification of one-cell mouse embryos in cryotubes

Area of Science:

• Cryobiology
• Developmental Biology
• Reproductive Science

Background:

• Preventing intracellular ice formation is crucial for successful cell cryopreservation.
• Vitrification, or converting cell water into a glass-like state, is a key strategy.
• Conventional methods often require high solute concentrations and rapid cooling.

Purpose of the Study:

• To investigate the effects of cooling rate, warming rate, and cryoprotectant concentration on 1-cell mouse embryo survival.
• To develop an effective vitrification method for 1-cell mouse embryos using cryotubes.

Main Methods:

• 1-cell mouse embryos were vitrified in cryotubes using ethylene glycol-based solutions (EFS20, EFS30, EFS40) with varying cryoprotectant concentrations.
• Vitrification involved direct immersion into liquid nitrogen after a brief equilibration period.
• Samples were warmed at rates of 34°C/min, 4,600°C/min, and 6,600°C/min.

Main Results:

• Low survival rates were observed with EFS40 regardless of warming rate.
• Survival improved significantly with higher warming rates (4,600°C/min and 6,600°C/min) for EFS20 and EFS30, indicating prevention of intracellular ice.
• Rapid warming of EFS20-vitrified embryos resulted in high in vitro blastocyst development and 43% term development after transfer to recipients.

Conclusions:

• Rapid warming is a critical factor for successful vitrification of 1-cell mouse embryos.
• A novel vitrification method using cryotubes and rapid warming demonstrates high efficacy for embryo cryopreservation.
• This method holds promise for improving assisted reproductive technologies.