Hybrid-model-based design of fill-freeze-thaw processes for human induced pluripotent stem cells considering productivity and quality

This work presents a hybrid-model-based design of a fill-freeze-thaw processes for human induced pluripotent stem (hiPS) cells. For freezing, we applied our previously presented single-cell model, which describes heat transfer, dehydration, and crystallization during freezing. New models have been devel-oped for filling and thawing. The accumulation of intracellular reactive oxygen species during filling and thawing was defined as the quality indicator and was described as a black-box model. Experimental re-sults provided the necessary parameter values. The time duration for filling and thawing was defined as the productivity indicator based on physical models. The overall fill-freeze-thaw model calculates the quality and productivity indicators given the process specifications, such as vial diameter and thawing temperature. In the case study for thawing, vial diameter largely affected the productivity. For the over-all fill-freeze-thaw process, the optimal thawing temperature and vial diameter for productivity changed significantly, depending on the acceptable quality specifications and cell demand. (c) 2021 Elsevier Ltd. All rights reserved.