Liposomes as Carriers for Large DNA Molecules

Liposomes are spherical structures composed of lipids, which imitate the lipid partition of cell membranes. Because of their ability to transport significant amounts of water-soluble molecules in their inner cavity, they are considered excellent carriers for the delivery of drugs and other active molecules. The long-term objective of this research is to utilize liposomes for precise and controlled delivery of genes toward targeted sites in the human body for the purpose of gene therapy. To achieve this goal, we focused on investigating and optimizing the load of nucleic acids into liposomes. Our experiments employed the hydration of lipid cakes with solutions containing plasmid DNA, production of unilamellar liposomes by extrusion, purification of liposomes by dialysis, and physical characterization by Dynamic Light Scattering and microscopy. Purified liposomes entrapping the plasmid DNA were assessed for nucleic acid load from the fluorescence that resulted upon interaction with intercalating agents. Our experimental results suggest that liposomes can incorporate amounts of DNA molecules sufficient for gene therapy. These findings support further explorations toward the utilization of sterically-stabilized liposomes that are functionalized with aptamers for specific targeting of cells and tissues. Such developments present the potential to improve the clinical outcome of gene therapies by minimizing the body’s immune response and other associated systemic risks.