Evolving concepts in the world of vitrification

Area of Science:

• Assisted Reproductive Technologies
• Biophysics
• Cryobiology

Background:

• Vitrification is a key technique in assisted reproduction, enabling embryo and oocyte banking.
• Shortened protocols for vitrification and cryoprotectant elution are increasingly used in clinical practice.
• Fundamental biophysical principles of vitrification remain critical despite protocol modifications.

Purpose of the Study:

• To clarify the fundamental biophysical principles governing vitrification processes.
• To review recent advancements in shortened vitrification and warming protocols.
• To identify knowledge gaps in optimizing cryopreservation techniques.

Main Methods:

• Review of current literature on vitrification protocols and biophysical principles.
• Analysis of data comparing conventional and shortened equilibration and rehydration protocols.
• Evaluation of factors affecting oocyte and blastocyst survival and development post-warming.

Main Results:

• Shortened equilibration can achieve comparable, but not identical, intracellular conditions for oocytes.
• Biological differences in blastocysts may limit the application of shortened protocols.
• One-step rehydration protocols are clinically used, but may depend on prior cryoprotectant exposure and solute content.

Conclusions:

• Fast vitrification and warming strategies can achieve outcomes equivalent to standard protocols.
• Logistical and physiological advantages may be offered by accelerated cryopreservation methods.
• Further research is needed in permeability estimation, modeling, and clinical studies to optimize vitrification protocols for robust outcomes.