Skip to main content
. 2023 Mar 11;29(5):343–353. doi: 10.1016/j.molmed.2023.02.004

Figure 2.

Figure 2

Trojan horse delivery of lipid nanoparticle (LNP)-encapsulated plasmid DNA across membrane barriers in brain.

(A) Electron micrograph of a Trojan horse LNP. The pegylated liposome encapsulating plasmid DNA is conjugated with a receptor-specific monoclonal antibody (MAb) at the tips of the polyethyleneglycol (PEG) strands on the surface of the LNP. The PEG-extended MAb is visualized with a 10-nm gold conjugate of a secondary antibody that binds the Trojan horse MAb on the LNP. Reproduced, with permission, from [16]; copyright © 2003 Elsevier. (B,C) Confocal microscopy of human U87 glioma cells at 3 h (B) and 24 h (C) of incubation with a fluoresceinated plasmid DNA encapsulated within a human insulin receptor (INSR) (HIR) MAb targeted LNP. At 3 h of incubation, the plasmid DNA is primarily located in the cytoplasm, with some distribution into the nucleolar compartment (B). At 24 h of incubation (C), the plasmid DNA is primarily localized to the nuclear compartment (C). Reproduced, with permission, from [61]; copyright © 2002 John Wiley & Sons. (D) Trojan horse LNPs encapsulated with plasmid DNA must traverse three barriers separating blood from the nuclear compartment of brain cells: (1) the blood–brain barrier (BBB), which comprises the luminal and abluminal membranes of the brain capillary endothelium; (2) the brain cell plasma membrane; and (3) the brain cell nuclear membrane. A MAb against the HIR, which is conjugated to the tips of the PEG strands at the surface of the LNP, binds the INSR expressed at the BBB to trigger receptor-mediated transcytosis of the LNP through the brain capillary endothelium. Following entry of the LNP into the brain extracellular space (ECS), HIRMAb then binds the INSR on the brain cell plasma membrane to trigger receptor-mediated endocytosis into the intracellular space (ICS) of brain cells. The INSR normally translocates to the nuclear membrane [63., 64., 65.], which enables delivery of the plasmid DNA encapsulated in LNPs to the nuclear compartment. Figure produced with Biorender.com.