Cord-Blood-Stem-Cell-Derived Conventional Dendritic Cells Specifically Originate from CD115-Expressing Precursors.

Maud Plantinga,Kitty W.M Bloemenkamp,Denise A.M.H Van Den Beemt,Ester Dünnebach,Colin G De Haar,Stefan Nierkens,Jaap Jan Boelens,Michal Mokry

doi:10.3390/cancers11020181

Abstract

Dendritic cells (DCs) are professional antigen-presenting cells which instruct both the innate and adaptive immune systems. Once mature, they have the capacity to activate and prime naïve T cells for recognition and eradication of pathogens and tumor cells. These characteristics make them excellent candidates for vaccination strategies. Most DC vaccines have been generated from ex vivo culture of monocytes (mo). The use of mo-DCs as vaccines to induce adaptive immunity against cancer has resulted in clinical responses but, overall, treatment success is limited. The application of primary DCs or DCs generated from CD34+ stem cells have been suggested to improve clinical efficacy. Cord blood (CB) is a particularly rich source of CD34+ stem cells for the generation of DCs, but the dynamics and plasticity of the specific DC lineage development are poorly understood. Using flow sorting of DC progenitors from CB cultures and subsequent RNA sequencing, we found that CB-derived DCs (CB-DCs) exclusively originate from CD115+-expressing progenitors. Gene set enrichment analysis displayed an enriched conventional DC profile within the CD115-derived DCs compared with CB mo-DCs. Functional assays demonstrated that these DCs matured and migrated upon good manufacturing practice (GMP)-grade stimulation and possessed a high capacity to activate tumor-antigen-specific T cells. In this study, we developed a culture protocol to generate conventional DCs from CB-derived stem cells in sufficient numbers for vaccination strategies. The discovery of a committed DC precursor in CB-derived stem cell cultures further enables utilization of conventional DC-based vaccines to provide powerful antitumor activity and long-term memory immunity.

Highlights

Dendritic cells (DCs) are able to elicit strong T-cell responses, which designates them as excellent candidates for vaccine strategies
Recent technological advances have enabled the isolation of reasonable numbers of primary DCs through apheresis that can be antigen loaded for use as a vaccine
We previously showed the feasibility of generating a good manufacturing practice (GMP)-compliant DC vaccine from a very limited number of Cord blood (CB) CD34+ cells [21]

Summary

Introduction

Dendritic cells (DCs) are able to elicit strong T-cell responses, which designates them as excellent candidates for vaccine strategies. The commonly used approach to generate DCs for immunotherapy. Vaccination with mo-DCs is feasible and safe, clinical efficacy in terms of overall survival is still limited [3,4]. Recent technological advances have enabled the isolation of reasonable numbers of primary DCs through apheresis that can be antigen loaded for use as a vaccine. The first trials using autologous primary DCs confirmed feasibility and safety [5,6,7,8,9] and showed improved progression-free survival and effective antitumor responses [6]. No randomized studies with mo-DCs vs. primary DCs have been performed, these data suggest the preference for using primary

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Conclusion