Scalable expansion of potent genetically modified human langerhans cells in a closed system for clinical applications

The administration of dendritic cell vaccines is a promising approach for cancer immunotherapy. Langerhans cells (LCs) that are genetically modified to express viral or tumor antigens are a dendritic cell subset of particular interest because they elicit potent antigen-specific immune responses. For clinical investigation, transduced, functional LCs must be generated in sufficient numbers using a scalable closed system that conforms to current good manufacturing practices. We therefore developed a process to expand CD34+ hematopoietic progenitor cell-derived LCs in serum-free medium using hydrophobic culture bags and compared their biologic function to that of LCs grown in plates or flasks. We obtained significantly higher yields of mature LCs in bags compared with plates or flasks. LCs grown in bags displayed comparable maturation phenotypes and were transduced by GaLV-pseudotyped retroviral vectors with the same efficiency as LCs grown in plates or flasks. Bag-expanded LCs effectively stimulated the proliferation of allogeneic T lymphocytes and the production of interferon-gamma by autologous CD8 T cells against the viral influenza matrix peptide or human tyrosinase. We have thus developed a scalable closed process to expand genetically modified, biologically functional CD34+ hematopoietic progenitor cell-derived LCs for phase I clinical trials.