Efficient generation of human dendritic cells from induced pluripotent stem cell by introducing a feeder-free expansion step for hematopoietic progenitors.

Dendritic cells (DCs) are rare innate immune cells that are essential regulators of antitumor, antiviral, and vaccine responses by the adaptive immune system. Conventional DCs, particularly the cDC1 subset, are most desired for DC-based immunotherapies, however, it can be difficult to isolate sufficient numbers of primary cells from patients. The most common alternate sources of DC are ex vivo monocyte-derived DC, although patient-derived monocytes are often dysfunctional. Induced pluripotent stem cells (iPSC) offer a promising solution, providing an opportunity for in vitro generating DCs that are suitable for allogenic off-the-shelf batch-manufactured cells. Here, we developed an in vitro protocol designed to maximize the yield of iPSC-derived DC progenitors, with the specific goal of generating cDC1-like cells. The iPSC-DCs subsets generated by our method could be partitioned by cell surface phenotypes of cDC1, cDC2, and DC3, but they were most transcriptionally similar to monocyte-derived DC (MoDC). Stimulated iPSC-DCs generated proinflammatory cytokines, expressed migratory chemokine receptors including CCR7, upregulated co-stimulatory molecules, and induced the proliferation of CD4/CD8 T-cells. Altogether these data indicate that iPSC-derived DCs have the potential to traffic through lymphatic endothelium and engage productively with T-cells. This method offers a promising step toward an expandable source of allogeneic human DCs for future applications.