Targeting vaccines to dendritic cells by mimicking the processing and presentation of antigens in xenotransplant rejection

Targeting the delivery of vaccines to dendritic cells (DCs) is challenging. Here we show that, by mimicking the fast and strong antigen processing and presentation that occurs during the rejection of xenotransplanted tissue, xenogeneic cell membrane-derived vesicles exposing tissue-specific antibodies can be leveraged to deliver peptide antigens and mRNA-encoded antigens to DCs. In mice with murine melanoma and murine thymoma, xenogeneic vesicles encapsulating a tumour-derived antigenic peptide or coated on lipid nanoparticles encapsulating an mRNA coding for a tumour antigen elicited potent tumour-specific T-cell responses that inhibited tumour growth. Mice immunized with xenogeneic vesicle-coated lipid nanoparticles encapsulating an mRNA encoding for the spike protein of severe acute respiratory syndrome coronavirus 2 elicited titres of anti-spike receptor-binding domain immunoglobulin G and of neutralizing antibodies that were approximately 32-fold and 6-fold, respectively, those elicited by a commercialized mRNA–lipid nanoparticle vaccine. The advantages of mimicking the biological recognition between immunoglobulin G on xenogeneic vesicles and fragment crystallizable receptors on DCs may justify the assessment of the safety risks of using animal-derived biological products in humans. By mimicking antigen processing and presentation during the rejection of xenotransplanted tissue, xenogeneic cell membrane-derived vesicles encapsulating peptide antigens or mRNA-encoded antigens function as vaccines targeted to dendritic cells.