Cytotoxic effect of cord blood derived natural killer cells on breast cancer cells

Abstract

OBJECTIVE Human natural killer (NK) cells are cluster of differentiation 3 (CD3)-CD56 + lymphocytes. NK cells can be obtained from various sources such as peripheral blood and cord blood. Among those, cord blood (CB) is an important cellular resource. The aim of this study is to determine the cytotoxic effect of freshly isolated CB derived NK cells toward breast cancer cells in vitro. METHODS CB mononuclear cells were isolated by Ficoll-Paque and NK cells were selected by with magnetic activated cell sorting (MACS) technique. CB-NK cell’s surface markers were quantified by flow cytometry analysis. Water-soluble tetrazolium salt cytotoxicity assay was used to measure cell viability; Annexin V/7-amino actinomycin D assay was used to measure apoptosis and necrosis. Enzyme-linked immuno-sorbent assay was used to determine perforin and Granzyme B activity of CB-NK cells. RESULTS Here, we show that CD56+ cells within the NK cell population were measured as 99.59% and CD314+ cells surface marker expression was measured as 99.48% after MACS selection. CB-NK cells exerted significant cytotoxicity toward Michigan cancer foundation 7 (MCF-7), MDA-231, and K562 tumor cells. Importantly, we show that CB-NK cells were able to kill MCF-7 and MDA-231 cells through apoptosis and necrosis, respectively. The amount of Granzyme B and perforin produced by CB-NK cells was measured as 50 ng/ml and 80 ng/ml, respectively. CONCLUSION Our findings confirm that freshly isolated CB-NK cells can be expanded in vitro with supplementation of various cytokines. We provide evidence that in these conditions, CB-NK cells exert efficiently cyto-toxic effect and induced apoptotic and necrotic cell death toward breast cancer cells.