W118 - Ex vivo Production Of Immunotherapeutic NK Cells From Cord Blood Or Mobilized Peripheral Blood CD34+ Cells Using Notch Ligand Delta-Like 4 Culture System

NK cell immunotherapy is becoming an attractive alternative to T-cell immunotherapy because they do not cause graft-versus-host disease, and not induce cytokine release syndrome. However, the limited availability of efficient clinical-grade ex vivo NK cell expansion, purification and genetic modification methods restricts the application of NK cell immunotherapy. Here, we developed an efficient, scalable, feeder cell-free and clinically applicable method for generating large numbers of immunotherapeutic NK cells from CD34⁺ cells based on our recently published immobilized DL-4 culture system supplemented with TNFα. The CD7⁺ progenitors obtained from DL-4/+TNFα cultures of CB or mPB CD34⁺ cells were able to efficiently differentiate into NK cells with frequencies up to >90% with an efficient transduction at 1 and 2 weeks upon subjecting them to feeder cell-free NK cell differentiation.  A single CB HSPC could give rise up to 10000 NK cells. The NK cells expressed the activation receptors and NK cell transcription factors, but not expressed the inhibitory KIRs and KLRG1. They expressed the cytotoxic molecules perforin and granzyme B and could be induced to express IFNg and TNFα, and undergo degranulation upon stimulation with myelogenous leukaemia cell line K562 cells. They could kill both K562 and THP1 cells. Therefore, the combination of our DL-4 culture system with NK cell differentiation/expansion procedure may provide a feeder-cell free efficient and clinically applicable method to produce large numbers of immunotherapeutic pure NK and CAR NK cell population. These results lay a groundwork towards an effective NK cell therapy platform for cancers and viral infections.