A molecular view on the escape of lipoplexed DNA from the endosome

Abstract

The use of non-viral vectors for in vivo gene therapy could drastically increase safety, whilst reducing the cost of preparing the vectors. A promising approach to non-viral vectors makes use of DNA/cationic liposome complexes (lipoplexes) to deliver the genetic material. Here we use coarse-grained molecular dynamics simulations to investigate the molecular mechanism underlying efficient DNA transfer from lipoplexes. Our computational fusion experiments of lipoplexes with endosomal membrane models show two distinct modes of transfection: parallel and perpendicular. In the parallel fusion pathway, DNA aligns with the membrane surface, showing very quick release of genetic material shortly after the initial fusion pore is formed. The perpendicular pathway also leads to transfection, but release is slower. We further show that the composition and size of the lipoplex, as well as the lipid composition of the endosomal membrane, have a significant impact on fusion efficiency in our models.

Barriers and Strategies of Cationic Liposomes for Cancer Gene Therapy

“…Instead, however, Bruininks et al. 16 found that fusion efficiency decreased as the size of lipoplexes increased because larger lipoplexes were more stable than their smaller counterparts during the process of endosomal membrane fusion.…”

“… 10 , 14 , 15 In addition, even if they manage to escape the RES trap and extravasate from vasculatures to the tumor tissues, particle characteristics determine whether they can successfully penetrate from the complex tumor environment into tumor cells, followed by effective ingestion via efficient internalization. Besides, endosomal/lysosomal entrapment is another obstacle for CLs to deliver genes to cytoplasm, 16 , 17 , 18 which is greatly affected by the fusogenic capability of CLs. 19 Furthermore, the reticular cytoskeletal network and the macromolecular crowding in the cytoplasm are not conducive to the transport of lipoplexes or DNA to the nucleus.…”

Cytosolic delivery of nucleic acids: The case of ionizable lipid nanoparticles

“…The fusion of DNA‐lipoplexes with the endosomal membrane has been recently investigated by CG simulations, providing insights on some of the key determinants for a successful transfection: vector size, lipoplex, and endosomal lipid composition 91 . The Martini force‐field was used to model a lipoplex consisting of DOTAP, as the cationic lipid, a double strand of DNA, and DOPE, as the helper lipid (1:4 DOTAP/DOPE ratio), and a mimic of the endosomal membrane consisting of PC and PS lipids (4:1 ratio).…”

Lipoplexes Could be Alternative to Viral Vectors in Gene Therapy

“…In a new study, researchers conducted advanced simulations to investigate how DNA/cationic liposome complexes or lipoplexes can deliver DNA fragments into cells (Bruininks et al, ). The simulations looked at how lipoplexes enter the cell and how they release the genes that they carry into the cells, with the goal of helping to optimize this process.…”