Human CD8 T cells generated in vitro from hematopoietic stem cells are functionally mature

<p>Abstract</p> <p>Background</p> <p>T cell development occurs within the highly specialized thymus. Cytotoxic CD8 T cells are critical in adaptive immunity by targeting virally infected or tumor cells. In this study, we addressed whether functional CD8 T cells can be generated fully <it>in vitro </it>using human umbilical cord blood (UCB) hematopoietic stem cells (HSCs) in coculture with OP9-DL1 cells.</p> <p>Results</p> <p>HSC/OP9-DL1 cocultures supported the differentiation of CD8 T cells, which were TCR/CD3^hiCD27^hiCD1a^negand thus phenotypically resembled mature functional CD8 single positive thymocytes. These <it>in vitro</it>-generated T cells also appeared to be conventional CD8 cells, as they expressed high levels of <it>Eomes </it>and low levels of <it>Plzf</it>, albeit not identical to <it>ex vivo </it>UCB CD8 T cells. Consistent with the phenotypic and molecular characterization, upon TCR-stimulation, <it>in vitro</it>-generated CD8 T cells proliferated, expressed activation markers (MHC-II, CD25, CD38), secreted IFN-γ and expressed Granzyme B, a cytotoxic T-cell effector molecule.</p> <p>Conclusion</p> <p>Taken together, the ability to direct human hematopoietic stem cell or T-progenitor cells towards a mature functional phenotype raises the possibility of establishing cell-based treatments for T-immunodeficiencies by rapidly restoring CD8 effector function, thereby mitigating the risks associated with opportunistic infections.</p

Comparative Study of Hematopoietic Differentiation between Human Embryonic Stem Cell Lines

Directed differentiation of human embryonic stem cells (hESCs) into any desired cell type has been hailed as a therapeutic promise to cure many human diseases. However, substantial roadblocks still exist for in vitro differentiation of hESCs into distinct cell types, including T lymphocytes. Here we examined the hematopoietic differentiation potential of six different hESC lines. We compare their ability to develop into CD34+ or CD34+CD45+ hematopoietic precursor populations under several differentiation conditions. Comparison of lymphoid potential of hESC derived- and fetal tissue derived-hematopoietic precursors was also made. We found diverse hematopoietic potential between hESC lines depending on the culture or passage conditions. In contrast to fetal-derived hematopoietic precursors, none of the CD34+ precursors differentiated from hESCs were able to develop further into T cells. These data underscore the difficulties in the current strategy of hESC forward differentiation and highlight distinct differences between CD34+ hematopoietic precursors generated in vitro versus in vivo