Comparative analysis of heparin based versus stromal cell supported methods for natural killer cell generation from umbilical cord blood stem cells.

Abstract

The ongoing search for a cure for leukemia has many possible paths. One of which focuses on cell therapy and the transfusion of natural killer (NK) cells into patients. The innate cytotoxicity of NK cells allows them to target and destroy leukemic cells. NK cells have already helped some patients achieve remission after failure of traditional therapies. There are at least two possible sources of NK cells. First, peripheral blood NK cells can be obtained from a related donor and second, NK cells can be differentiated and expanded from unrelated donor umbilical cord blood (UCB) hematopoietic stem cells (HSCs). The later approach has the advantage of selecting donors with high cytotoxic capacity and cryopreservation of cells to be infused when needed. We previously described a method to generate NK cells from UCB-derived HSCs, using a murine fetal liver stromal cell line. However, use of murine cells is likely not allowed for human use. Thus, alternate clinical applications incorporating combinations of cytokines, additives, and procedural steps that would lead to highly cytotoxic NK cells are needed. The present research focuses on a comparison of a stromal cell supported method versus a liquid only based method for generating NK cells from UCB stem cells. Our comparative analysis focused on these two approaches in their ability to expand NK cells from stem cells and the resultant phenotypic functional capabilities of these HSC-derived NK cells. We demonstrate significant differences in absolute NK cell counts, nominal phenotypic differences, and similar functional capabilities between the two methods. Improvements in the techniques that result in NK generation will aid in the clinical use of these cells that have the potential to revolutionize leukemia treatment.