Complex Size and Surface Charge Determine Nucleic Acid Transfer by Fusogenic Liposomes

• Main Authors: Marco Hoffmann, Nils Hersch, Sven Gerlach, Georg Dreissen, Ronald Springer, Rudolf Merkel, Agnes Csiszár, Bernd Hoffmann
• Format: Article
• Language: English
• Published: MDPI AG 2020-03-01
• Series: International Journal of Molecular Sciences
• Subjects: fusogenic liposomes; transfection; nucleic acid complexation; membrane fusion
• Online Access: https://www.mdpi.com/1422-0067/21/6/2244

Highly efficient, biocompatible, and fast nucleic acid delivery methods are essential for biomedical applications and research. At present, two main strategies are used to this end. In non-viral transfection liposome- or polymer-based formulations are used to transfer cargo into cells via endocytosis, whereas viral carriers enable direct nucleic acid delivery into the cell cytoplasm. Here, we introduce a new generation of liposomes for nucleic acid delivery, which immediately fuse with the cellular plasma membrane upon contact to transfer the functional nucleic acid directly into the cell cytoplasm. For maximum fusion efficiency combined with high cargo transfer, nucleic acids had to be complexed and partially neutralized before incorporation into fusogenic liposomes. Among the various neutralization agents tested, small, linear, and positively charged polymers yielded the best complex properties. Systematic variation of liposomal composition and nucleic acid complexation identified surface charge as well as particle size as essential parameters for cargo-liposome interaction and subsequent fusion induction. Optimized protocols were tested for the efficient transfer of different kinds of nucleic acids like plasmid DNA, messenger RNA, and short-interfering RNA into various mammalian cells in culture and into primary tissues.