Induction of Human T Cell Development In Vitro with OP9-DL4-7FS Cells Expressing Human Cytokines

For nearly a generation now, OP9-DL1 and OP9-DL4 cells have provided an efficient and reliable cell system to generate T cells from mouse and human hematopoietic stem cells (HSCs) and pluripotent stem cells. OP9-DL1 and OP9-DL4 were originally derived from the OP9 mouse bone marrow stromal cell line, which was transduced to ectopically express Delta-like 1 or 4 proteins, respectively. OP9-DL cells mimic the thymic microenvironment in that when cocultured with mouse or human (h) HSCs, they interact with and activate Notch receptors present on HSCs, required for T cell differentiation. The HSC/OP9-DL cocultures require additional cytokines that are necessary for survival and proliferation of hematopoietic cells. For hHSCs, these factors are interleukin-7 (IL-7), stem cell factor (SCF), and FMS-like tyrosine kinase 3 ligand (FLT3L) that are normally exogenously added to the cocultures. In this chapter, we describe methods for establishing a novel and improved version of OP9-DL4 cells, called OP9-DL4-7FS cells that circumvent the addition of these costly cytokines, by transducing OP9-DL4 cell line to express human IL-7, FLT3L, and SCF (7FS). Herein, we describe the protocol for the generation of OP9-DL4-7FS cells and the conditions for OP9-DL4-7FS/hHSC coculture to support T cell lineage initiation and expansion while comparing it to the now "classic" OP9-DL4 coculture. The use of OP9-DL4-7FS cell system will provide an improved and cost-effective method to the commonly used OP9-DL/HSC coculture for studying both mouse and human T cell development.