Efficient Regeneration of Human Vα24 Invariant Natural Killer T Cells and Their Anti-Tumor Activity In Vivo.

Reprogramming of antigen-specific T lymphocytes into induced pluripotent stem cells (iPSCs) and their subsequent re-differentiation has enabled expansion of functional T lymphocytes in vitro, thus opening up new approaches for immunotherapy of cancer and other diseases. In this study, we have established a robust protocol to reprogram human invariant NKT (Vα24 iNKT) cells, which have been shown to act as cellular adjuvants and thus exert anti-tumor activity in mice and humans, and to re-differentiate the iNKT cell-derived iPSCs into functional iNKT cells. These iPSC-derived iNKT cells (iPS-Vα24 iNKT cells) can be activated by ligand-pulsed dendritic cells (DCs) and produce a large amount of interferon-γ upon activation, as much as parental Vα24 iNKT cells, but exhibit even better cytotoxic activity against various tumor cell lines. The iPS-Vα24 iNKT cells possess significant anti-tumor activity in tumor-bearing mice and can activate autologous NK cells upon activation by ligand-pulsed DCs in the NOG mouse model in vivo, further extending their therapeutic potential. This study thus provides a first proof of concept for the clinical application of human iPS-Vα24 iNKT cells for cancer immunotherapy. Stem Cells 2016;34:2852-2860.