Human pluripotent stem cells as a source of dendritic cells to induce immune tolerance

Abstract

Dendritic Cells (DCs) are professional antigen presenting cells that play a crucial role in the induction of immune tolerance. Although DCs have been a potential target for immunotherapy, the amount of DCs in blood source is limited and ex vivo expansion has been inefficient. Human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs) provide a great source in cell-based therapy because of their self-renewal ability and pluripotency. My project focuses on generating tolerogenic DCs (tDCs) from human pluripotent stem cells (i.e. hESCs and iPSCs) and their characterization.

Specifically, hESCs and hiPSCs were first differentiated to hematopoietic progenitor cells (HPCs) using three different methods (i.e. bone-marrow stromal cell co-culture and two previously reported defined medium methods). The hESC/iPSC-differentiated hematopoietic progenitor cells (HPCs) were characterized by their surface phenotype using flow cytometry. Then the hESC/iPSC-differentiated immature DCs were further expanded and differentiated from the hESC/iPSCdifferentiated CD34+ HPCs with the addition of granulocyte-macrophage colony-stimulating factor (GM-CSF) and Interleukin 4 (IL-4). Tolerogenic properties were introduced by treating hESC-differentiated DCs with rapamycin. The treated DCs were characterized for their tolerogenicity by examining their expression of PDL1, PDL2, ICOS and CD40 etc., and their ability to promote regulatory T cells (Treg) differentiation. All these were compared with monocyte-derived tDCs.

In summary, this study has examined the potential of using pluripotent stem cells-derived DCs as a cell source for immune tolerance induction therapy.