iPSCs in NK Cell Manufacturing and NKEV Development

Abstract

Natural killer (NK) cell immunotherapies for cancer can complement existing T cell therapies while benefiting from advancements already made in the immunotherapy field. For NK cell manufacturing, induced pluripotent stem cells (iPSCs) offer advantages including eliminating donor variation and providing an ideal platform for genome engineering. At the same time, extracellular vesicles (EVs) have become a major research interest, and purified NK cell extracellular vesicles (NKEVs) have been shown to reproduce the key functions of their parent NK cells. NKEVs have the potential to be developed into a standalone therapeutic with reduced complexity and immunogenicity compared to cell therapies. This review explores the role iPSC technology can play in both NK cell manufacturing and NKEV development.

Keywords: cancer; exosomes; extracellular vesicles; genome engineering; immunotherapy; induced pluripotent stem cells; manufacturing; natural killer cells.

Figure 1

Functions of NK cells and NKEVs. The key functions of NK cells are immune surveillance, cytotoxicity and tumor suppression, and immune modulation, all of which involve both NK cells and NKEVs. (A) NK cell immune surveillance depends on the interaction of activating and inhibitory receptors with target cells. In suppressive TMEs, NK cells are inhibited by PD-L1 on tumor cells and tumor cell-secreted TGF-β and IL-10. Decreased oxygen concentration, increased lactate production, and decreased available nutrients also inhibit NK cells. NKEVs exhibit tumor affinity, and NKEV delivery of miR-186 to NK cells decreases TGFBR1/2 expression, fortifying them in suppressive TMEs. (B) Cytotoxicity and tumor suppression by NK cells depends on either CD16 regulated ADCC or degranulation of vesicles containing perforin and granzyme B in response to the combined activation of activating receptors. NKEVs directly deliver cytotoxic effector cargo of perforin, granulysin, granzyme A and B, as well as miRNAs miR-186 and miR-3607 to tumor cells. (C) NK cells produce immunomodulatory cytokines and chemokines in response to activation, directly activating CD8⁺ T cells, and stimulating dendritic cells to activate both CD8⁺ and CD4⁺ T cells, which subsequently attack tumors. Meanwhile, NKEVs increase CD80, CD86 and HLA-DR expression on monocytes, increase CD25 expression and decrease PD-1 expression on CD3⁺ T cells, and increase the total NK cell population and the CD56^dim NK cell fraction.

Figure 2

iPSCs in EV production. iPSCs can be differentiated into various cell types that have therapeutic potential. iPSC-NK cells have the advantages of increased expansion potential, the production of biologically young cells, and less donor variation compared to primary NK cells. For EV production, several iPSC-derived cells and iPSCs themselves have been shown to produce functional EVs. However, for NK cells, studies investigating iPSC-NKEVs have not been reported, raising the important question of whether iPSC-NK cells produce EVs. NKEVs can reproduce the functions of NK cell therapies while reducing the complexity and immunogenicity of the final therapeutic product, thus increasing safety. These features highlight how iPSC-NKEVs represent an important direction for NKEV research.