Efficient production of T cells from mouse pluripotent stem cells by controlled expression of Lhx2

LIM-homeobox transcription factor Lhx2 induces ex vivo amplification of adult hematopoietic stem cells (HSCs) in mice. We previously showed that engraftable HSC-like cells are generated from mouse embryonic stem cells (ESCs) and induced pluripotent stem cells by enforced expression of Lhx2. However, when these HSC-like cells were transplanted into irradiated congenic mice, donor-derived T cells were barely detectable, whereas other lineages of hematopoietic cells were continuously produced. Here we investigated T-cell differentiation potential of the Lhx2-induced HSC-like cells using ESCs carrying doxycycline (dox)-inducible Lhx2 expression cassette. Dox-mediated over-expression of Lhx2 conferred a self-renewing activity to ESC-derived c-Kit(+) CD41(+) embryonic hematopoietic progenitor cells (HPCs), thereby converting them to HSC-like cells. When these HSC-like cells were transplanted into irradiated immunodeficient mice and they were supplied with a dox-containing water, CD4/8 double negative T cells were detected in their thymi. Once the Lhx2 expression was terminated, differentiation of CD4/8 double positive and single positive T cells was initiated in the thymi of transplanted mice and mature T cells were released in the peripheral blood. These results showed that engraftable HSC-like cells with full hematopoietic potential can be obtained from ESCs by the conditional expression of Lhx2.