Directed differentiation of embryonic stem cells to the T-lymphocyte lineage

Hematopoiesis is the highly regulated and complex process by which blood cells are formed. Hematopoiesis can be achieved in vitro by the differentiation of embryonic stem cells (ESCs) into hematopoietic lineage cells. Differentiation of ESCs initially gives rise to mesoderm colonies that go on to form hemangioblast cells, which possess endothelial and hematopoietic lineage potential. While the differentiation of several hematopoietic lineages from ESCs, such as erythrocytes and macrophages, can be easily recapitulated in vitro, T-cell differentiation requires additional Notch-dependent signals for their generation. Keeping with this, ESCs induced to differentiate with OP-9 cells, a bone marrow-derived stromal cell line, give rise to erythro-myeloid cells and B lymphocytes, while the expression of an appropriate Notch ligand, such as Delta-like 1, on OP-9 cells (OP9-DL1) is required to support the generation of T-cells in vitro. Here, we describe an updated and streamlined protocol for the generation of T-lineage cells from mouse ESCs cultured on OP9-DL1 cells. This approach can facilitate studies aimed to assess the effects of environmental and genetic manipulations at various stages of T-cell development.