We evaluated the phenotype and function of fresh and frozen NK cells differentiated in vitro. We also assessed whether the concentration of NK cells at the time of freezing had an impact on cell viability.
We found that cell concentration of NK cells at the time of freezing did not have an impact on their viability and on cell recovery post-thaw. Moreover, freezing of differentiated NK cells in vitro did not affect their phenotype, cytotoxicity and degranulation capacity toward K562 cells, cytokine production and proliferation.
We are therefore able to generate large numbers of functional NK cells from CB CD34+ cells that maintain the same phenotype and function post-cryopreservation, which will allow for multiple infusions of a highly cytotoxic NK cell product.