Harnessing Notch Signaling to Enhance the Generation and Functionality of Human Conventional Type I Dendritic Cells for Cancer Immunotherapy Applications

Conventional dendritic cell type I (cDC1) are essential for an effective antitumor immune response, and their presence in the tumor microenvironment is positively correlated with clinical benefits. The extremely low frequency of these cell subsets in peripheral blood limits their application as a cellular vaccine for cancer immunotherapy. Developing a robust in vitro culture system for their large-scale generation from hematopoietic stem cells (HSCs) is a potential approach for generating cDC1-based cellular vaccines. We have developed a novel culture system by exploiting the Notch signaling requirement for cDC1 differentiation from HSCs and successfully generated billions of cDC1s from every million input CD34+ cells. We compared the gene expression profiles of cDC1s generated under feeder-free conditions or on feeders with or without Notch ligands using bulk RNA sequencing. Our results confirm that the in vitro-generated cDC1s are bona fide cDC1s and closely resemble naturally circulating cDC1s in vivo. The cDC1 generation system represents a significant opportunity to develop novel cellular vaccines for cancer immunotherapy, leveraging cross-presenting DC subsets.