"Universal Warming" protocol for vitrified oocytes to streamline cell exchange for transnational donation programs: a...

Area of Science:

• Reproductive Medicine and Cryobiology
• Oocyte Cryopreservation
• Assisted Reproductive Technologies

Background:

• Shipping oocytes between assisted reproductive (AR) centers is common practice.
• Current protocols often involve specific vitrification and warming kits from the same manufacturer.
• Combining different vitrification/warming kits may pose legal and regulatory challenges for AR centers.

Purpose of the Study:

• To evaluate the clinical efficacy of a "Universal Warming" protocol for shipped oocytes.
• The protocol utilizes sequential extracellular cryoprotectant (ECCP) concentrations (1 M and 0.5 M).
• To assess the feasibility of using different warming kits with a standardized warming protocol.

Main Methods:

• A retrospective, multi-center, transnational observational study involving 1,898 warmed oocytes.
• Oocytes were vitrified using the Kitazato kit and warmed using either the Kitazato warming kit (KK group, n=939) or the Vit Kit®-Thaw (KI group, n=959).
• Primary endpoint was oocyte survival rate; secondary endpoints included fertilization, blastulation, implantation, and live birth rates.

Main Results:

• Oocyte survival rates were comparable between groups: 84.6% in KK vs. 82.1% in KI.
• Fertilization rate was significantly higher in the KI group (80.4%) compared to the KK group (75.7%).
• Blastulation, implantation, and live birth rates were statistically similar between the KK and KI groups.

Conclusions:

• The "Universal Warming" protocol is clinically effective and simplifies the exchange of vitrified oocytes between AR centers.
• This protocol overcomes potential regulatory, commercial, and availability issues associated with using manufacturer-specific warming kits.
• It supports international collaboration and standardization in oocyte cryopreservation and transport.