Modeling for the Optimization of the Loading of Cryoprotectants to Oocyte

Keimyung Medical Journal 2013;32(2):161-167.

난자 내로의 동결보존제 유입 궤적 최적화 모델링

허윤석

Abstract

The inevitable use of the cryoprotectants (CPAs) during cryopreservation affects the low viability of the cryopreserved oocytes and pregnancy rates either through CPA toxicity or osmotic injury. The goal of this study is to develop an optimized CPA loading profile for minimizing the exposure to CPA and the volume change of oocyte. A computational simulation has been conducted to rationally design protocols that minimize the exposure to cryoprotectant and the volume changes of oocyte. Using a coupled differential equation with hydraulic conductivity; solute permeability; and reflection coefficient of oocyte; oocyte volume changes are predicted as function of time with the changes of the external CPA concentration. The computational simulation suggests that controlled CPA loading profile produces less volume changes and less total amounts of CPA exposure than uncontrolled CPA loading profile. Specifically; the volumetric change (less than 10%) was obtained with the linear CPA loading profile while the volumetric change in the conventional step-wise CPA profile was over 30%. The reduced volume change can reduce the cellular damage from the osmotic injury during the pretreatment for the cryopreservation. Thus; I believe that this computational modeling with controlled CPA profile will eventually help future advances in assisted reproductive technologies and fertility preservation as well as in single cell analysis technology.

Key Words: CPA toxicity, Cryopreservation, Cryoprotectants (CPAs), Osmotic injury