ABSTRACT
<p><b>OBJECTIVE</b>To establish a novel method for ex vivo expansion of natural killer cells from human umbilical blood, so as to provide the basis for NK cell therapy.</p><p><b>METHODS</b>Mononucleated cells from human umbilical blood were harvested and suspended in a serum-free medium containing 5% autologous plasma, recombinant human IL-15 (50 ng/ml) and hydrocortisone sodium succinate (5×10 mol/L) at a concentration of 1.5×10/ml, then the cells were seeded into flasks pre-coated with heparin sodium (100 U/cm) or/and anti-human CD16 antibody (1 µg/cm). After culture for 2 weeks, the cells were harvested and counted. Ratios of CD3/CD56 of the cells were determined by flow cytometry. MTT test was performed to assess the cytotoxicity against K562 cells with graded ratios of effector/target cells.</p><p><b>RESULTS</b>In contrast to the cells in flasks without pre-coating, the attached colonies appeared predominantly within 1 week of culture from heparin- and antibody-coated groups. The cell numbers from the pre-coated groups were significantly higher than that of uncoated one after culture for 2 weeks. Furthermore, the ratios of CD3/CD56 cells were much higher in pre-coated groups, and that of the cells from flasks pre-coated with heparin and antibody were the highest (all the P values <0.01). MTT test showed that the cytotoxic activity of the cells stimulated by precoating were much more potent than that of the cells without the stimulation.</p><p><b>CONCLUSION</b>Advantageous expansion of NK cells can be achieved by precoating with heparin and anti-CD16 antibody, and also by supplement with IL-15 and hydrocortisone into the media, so the umbilical NK cells with high purity and potent cytotoxicity can be obtained.</p>