Induction of γδT cells from HSC-enriched BMCs co-cultured with iPSC-derived thymic epithelial cells.

T cells bearing I³I´ antigen receptors have been investigated as potential treatments for several diseases, including malignant tumours. However, the clinical application of I³I´T cells has been hampered by their relatively low abundance in vivo and the technical difficulty of inducing their differentiation from hematopoietic stem cells (HSCs) in vitro. Here, we describe a novel method for generating mouse I³I´T cells by co-culturing HSC-enriched bone marrow cells (HSC-eBMCs) with induced thymic epithelial cells (iTECs) derived from induced pluripotent stem cells (iPSCs). We used BMCs from CD45.1 congenic C57BL/6 mice to distinguish them from iPSCs, which expressed CD45.2. We showed that HSC-eBMCs and iTECs cultured with IL-2 + IL-7 for up to 21 days induced CD45.1+ I³I´T cells that expressed a broad repertoire of VI³ and VI´ T-cell receptors. Notably, the induced lymphocytes contained few or no αsT cells, NK1.1+ natural killer cells, or B220+ B cells. Adoptive transfer of the induced I³I´T cells to leukemia-bearing mice significantly reduced tumour growth and prolonged mouse survival with no obvious side effects, such as tumorigenesis and autoimmune diseases. This new method suggests that it could also be used to produce human I³I´T cells for clinical applications.