Polyelectrolyte‐Enrobed Cancer Cells in View of Personalized Immune‐Therapy

Targeting the immune system with a personalized vaccine containing cues derived from the patient's malignancy might be a promising approach in the fight against cancer. It includes neo‐antigens as well as nonmutated tumor antigens, preferentially leading to an immune response that is directed to a broader range of epitopes compared to strategies involving a single antigen. Here, this paper reports on an elegant method to encapsulate whole cancer cells into polyelectrolyte particles. Porous and nonaggregated microparticles containing dead cancer cells are obtained by admixing mannitol and live cancer cells with oppositely charged polyelectrolytes, dextran sulfate (anionic polysaccharide), and poly‐l‐arginine (cationic polypeptide) prior to atomization into a hot air stream. It shows that the polyelectrolyte‐enrobed cancer cells, upon redispersion in phosphate buffered saline buffer, are stable and do not release cell proteins in the supernatant. In vitro experiments reveal that the particles are nontoxic and strongly increase uptake of cell lysate by dendritic cells. In vitro assessment of antigen presentation by dendritic cells reveal the potential of the polyelectrolyte‐enrobed cancer cells as promotors of antigen cross‐presentation. Finally, it is demonstrated that the immunogenicity can be enhanced by surface adsorption of a polymer‐substituted TLR7‐agonist.