Transcriptional comparison of in vitro and in vivo generated human dendritic cells

Classical dendritic cells (cDCs) are rare sentinel cells specialized in the regulation of adaptive immunity. Modelling cDC development is both crucial to study cDCs and harness their potential in immunotherapy. Here we present a novel in vitro differentiation approach using cord blood CD34+ hematopoietic stem and progenitor cells (HSPCs) co-cultured with bone marrow-derived murine mesenchymal cell line (MS5) engineered to express human FLT3L, SCF and CXCL12 (MS5_FS12). We also show that the engraftment of engineered mesenchymal stromal cells (MS5_FS12) together with CD34+ HSPCs creates an in vivo synthetic niche in the dermis of immunodeficient mice driving the differentiation of cDCs and CD123+AXL+CD327+ pre/AS-DCs. This approach provides a unique platform recapitulating the full spectrum of cDC subsets enabling their functional characterization in vivo. Overall design: RNA-seq study comparing human dendritic cell subsets differentiated in vitro and in vivo from cord blood-derived CD34+ HSPCs. Hematopoietic progenitors were either co-cultured in vitro or co-injected in NSG mice with bone marrow-derived murine mesenchymal cell line (MS5) engineered to co-express human FLT3L, SCF and CXCL12 (MS5_FS12).