Background: Human embryonic stem cells (hESC) are derived from early stage blastocysts and are characterized by the ability to both self-renew and to generate differentiated functional cell types. One of the major challenges in the field of hESC research, is to set up a culture system that drives hESC down a particular lineage fate. To date, studies reporting hematopoietic development have not provided evidence on the differentiation capacity of hESC into T lineage cells in vitro. Material and

Methods: hESC line H1 (National Institutes of Health [NIH] code: WA01), Wisconson, Madison, USA) was used (Passage 30–60) in all experiments. The hESC line was kept in an undifferentiated state on MEFs as previously described. OP9 cells and OP9 cells that express high levels of the Notch ligand Delta-like 1 (OP9-DLL1, a gift from J. C. Zuniga-Pflücker, University of Toronto, Canada) were cultured as previously described in MEM-α with 20 % FCS.

Results: Our data show that T cells can be generated in vitro from hESC in a robust and highly reproducible manner using the sequential exposure of hESC to the murine OP9 cell line and OP9-DLL1. On OP9 stromal layers, a CD34highCD43dim hematopoietic precursor population is generated that is confined to vascular-like structures, reminiscent of blood islands that emerge during in vivo embryonic development. This precursor population becomes T lineage committed when exposed to OP9-DLL1 monolayers, passing sequentially through a CD34+CD7+ phenotype, a CD4+CD8+ double positive intermediate stage and eventually differentiates into a mature T cells. Polyclonal T cells are generated, cell receptor (TCR) alpha-beta and TCRgamma-delta which are functional based on proliferative capacity and production of cytokines after TCR crosslinking.

Conclusion: We show that mature and functional T cells can be generated from hESC using well defined in vitro conditions. This protocol in combination with the recently described induced pluripotent cells may find clinical applicability in tumor immunology.

Disclosures: No relevant conflicts of interest to declare.

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