The Role of Amnion Membrane-Derived Mesenchymal Stem Cells on Differentiation and Expansion of Natural Killer Cell Progenitors Originated From Umbilical Cord Blood Mononuclear Cells

Natural killer (NK) cells are members of the innate immune system. Their unique properties, including recognition of viral infected and tumor cells without major histocompatibility complex (MHC) restriction or prior sensitization, make them a suitable choice for immunotherapy. Low numbers of NK cells in circulating blood is the most important obstacle for this goal. The aim of this study was to make an optimum in vitro condition to proliferate and differentiate cord blood (CB)-NK cell progenitors to mature NK cells, which can be used for cell therapy. In our study, CB-Mononuclear Cells’ (MNCs) CD3+ lymphocytes were positive depleted using immunomagnetic microbeads. This CD3-depleted (CD3-dep) CB - MNCs compartment was used for in vitro expansion with or without a layer of amnion membrane mesenchymal stem cells (MSCs) in combination with cytokines that are essential for NK cells expansion (IL-2, IL-3, IL-15, and FLT3 ligand). The expansion period lasted for one week. On day seven, immunophenotype and fold expansion of differentiated cells were measured. Combination of cytokines and MSC layer yielded significant fold expansion in comparison with cytokines without feeder conditions (day 7: 5.2 ± 1.12 and 2 ± 0.78, respectively, P < 0.05). CD3-/CD56+ cells percentage increased during the culture period in MSCs/with cytokine and cytokine/without feeder, respectively (day 0: 4.4 ± 0.42% and day 7: 22.9 ± 3.6% and 13.9 ± 1.92 % for MSC/with cytokine and cytokine without feeder, respectively). Our results suggested that CB-NK cells progenitors could proliferate and differentiate on feeder layer of amnion membrane MSCs in combination with specific cytokines to produce NK cells for immunotherapy