Liposomes and other nanoparticles as cancer vaccines and immunotherapeutics
Abstract
The uptake, processing and presentation of antigen by antigen presenting cells (APCs) such as macrophages and dendritic cells (DCs) plays a crucial role in the development of vaccines and immunotherapies against infectious diseases and cancer. Liposomes are nanoparticles composed of lipids/phospholipids that can be produced to exhibit properties mimicking those seen in pathogens; thus empowering liposomes with an inherent adjuvant activity and an ability to induce both humoral and cell-mediated immune responses. In addition to their adjuvanticity, liposomes can deliver to APCs large amounts of antigen, and immunostimulatory factors; they can readily incorporate danger or DC maturation signals, and be surface-modified to promote their active targeting to specific receptors on cells. Liposomes can also encapsulate or form complexes (lipoplexes) with plasmid DNA and small interfering RNA, enabling targeting of these nucleic acids directly to APCs as a DNA vaccine or to enhance immune responses. Since liposomes can be readily manipulated, are biocompatible and biodegradable, and are efficacious with a good record of safety, they clearly exhibit the attributes of potent arsenals for manipulating immune function and for developing more effective cancer vaccines and immunotherapies.