The cryo-sensitivity of NK cells: overcoming post-thaw decline

The clinical translation of natural killer (NK) cell-based immunotherapies is fundamentally constrained by the lack of optimized cryopreservation protocols. While many hematopoietic cells tolerate ‘standard’ freezing methods, NK cells exhibit unique sensitivities that result in highly variable post-thaw recovery and diminished cytotoxicity. This review analyzes the biophysical principles of cryobiology, the molecular vulnerabilities of NK cells, and the critical limitations of traditional slow-cooling and DMSO-based techniques. Leveraging advances in new cryoprotectant technologies and targeted molecular tools, specialized, NK-specific cryopreservation strategies are emerging. Advances in automated workflows for NK cell production and pre-/post-cryopreservation handling are addressing critical roadblocks in NK cell manufacturing. Collectively, these advancements in NK cell cryopreservation are paving the way for scalable, ‘off-the-shelf’ allogeneic immunotherapies that can be manufactured centrally and delivered immediately to patients, bypassing the logistical delays of traditional cell-based treatments.