Cytokine-Treated Natural Killer Cells Derived from Cord Blood Haematopoietic Stem Cells Exhibit Potential Cytotoxicity Against Cancer Cells

Background: Despite substantial efforts to leverage natural killer (NK) cells in cancer immunotherapy, challenges associated with limited cell numbers and sources persist. In this study, our objective is to differentiate NK cells from cord blood hematopoietic stem cells (CB-HSCs) and assess their anti-tumor effects. Methods: Cord blood samples were obtained from pregnant women undergoing normal delivery. Mononuclear cells (MNC) were isolated by gradient centrifugation. Subsequently, HSCs were isolated using the MACs cell separation kit. The isolated HSCs were cultured in NK cell differentiation and expansion media for 21 days and 7 days, respectively. The NK cells were examined for expression of activating markers, cytokine secretion and cytolytic effects by flow cytometry, ELISA and XTT tests, respectively. Results: High-purity HSCs and NK cells were obtained in this study. The CB-HSCs-derived NK cells exhibited significantly higher expression of NKG2D, NKp30, NKp44 and NKp46 receptors (at day 28 of treatment) after treatment by IL-15 and IL-2, compared to the early differentiated NK cells (day 21). NK cells derived from CB-HSCs treated with the combination of IL-15 and IL-2 could robustly lyse breast cancer MCF-7 and K562 cells. Also, the obtained NK cells were able to release higher amounts of TNF-α and IFN-γ cytokines in response to tumor cell experiences. Conclusions: Our findings showed that functionally active CB-HSCs-derived NK cells can be successfully generated ex vivo using a cytokine cocktail without a need for stroma for potential use in the cancer immunotherapy.