Exosome-based tumor antigens-adjuvant co-delivery utilizing genetically engineered tumor cell-derived exosomes with immunostimulatory CpG DNA

Biomaterials. 2016 Dec:111:55-65. doi: 10.1016/j.biomaterials.2016.09.031. Epub 2016 Oct 3.


For cancer immunotherapy via tumor antigen vaccination in combination with an adjuvant, major challenges include the identification of a particular tumor antigen and efficient delivery of the antigen as well as adjuvant to antigen-presenting cells. In this study, we proposed an efficient exosome-based tumor antigens-adjuvant co-delivery system using genetically engineered tumor cell-derived exosomes containing endogenous tumor antigens and immunostimulatory CpG DNA. Murine melanoma B16BL6 cells were transfected with a plasmid vector encoding a fusion streptavidin (SAV; a protein that binds to biotin with high affinity)-lactadherin (LA; an exosome-tropic protein) protein, yielding genetically engineered SAV-LA-expressing exosomes (SAV-exo). SAV-exo were combined with biotinylated CpG DNA to prepare CpG DNA-modified exosomes (CpG-SAV-exo). Fluorescent microscopic observation revealed the successful modification of exosomes with CpG DNA by SAV-biotin interaction. CpG-SAV-exo showed efficient and simultaneous delivery of exosomes with CpG DNA to murine dendritic DC2.4 cells in culture. Treatment with CpG-SAV-exo effectively activated DC2.4 cells and enhanced tumor antigen presentation capacity. Immunization with CpG-SAV-exo exhibited stronger in vivo antitumor effects in B16BL6 tumor-bearing mice than simple co-administration of exosomes and CpG DNA. Thus, genetically engineered CpG-SAV-exo is an effective exosome-based tumor antigens-adjuvant co-delivery system that will be useful for cancer immunotherapy.

Keywords: Cancer vaccine; CpG DNA; Drug delivery; Exosomes; Genetic engineering; Tumor antigens.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adjuvants, Immunologic / administration & dosage*
  • Adjuvants, Immunologic / genetics
  • Animals
  • Antigens, Neoplasm / administration & dosage*
  • Antigens, Neoplasm / genetics
  • Antigens, Neoplasm / immunology*
  • Cell Line, Tumor
  • CpG Islands / genetics
  • DNA / genetics*
  • Drug Combinations
  • Exosomes / genetics
  • Exosomes / immunology*
  • Genetic Engineering / methods*
  • Immunization / methods
  • Immunotherapy / methods
  • Male
  • Mice
  • Mice, Inbred BALB C
  • Mice, Inbred C57BL
  • Mice, Nude
  • Neoplasms, Experimental / genetics
  • Neoplasms, Experimental / therapy*
  • Treatment Outcome


  • Adjuvants, Immunologic
  • Antigens, Neoplasm
  • Drug Combinations
  • DNA