A system that permits the delivery of cargoes to the lung endothelium would be extraordinarily useful in terms of curing a wide variety of lung-related diseases. This study describes the development of a multifunctional envelope-type nanodevice (MEND) that targets the lung endothelium, delivers its encapsulated siRNA to the cytoplasm, and eradicates lung metastasis. The key to the success can be attributed to the presence of a surface-modified GALA peptide that has dual functions: targeting the sialic acid-terminated sugar chains on the pulmonary endothelium and subsequently delivering the encapsulated cargoes to the cytosol via endosomal membrane fusion, analogous to the influenza virus. The active targeting of MENDs without the formation of large aggregates was verified by intravital real-time confocal laser scanning microscopy in living lung tissue. The GALA-modified MEND is a promising carrier that opens a new generation of therapeutic approaches for satisfying unmet medical needs in curing lung diseases.
The development of efficient gene delivery systems targeting the lung endothelium remains a serious challenge. This study reports on the design and optimization of a multifunctional envelope‐type nanodevice (MEND) for an efficient siRNA delivery to the lung endothelium based on GALA‐peptide targeting ability. The incorporation of a pH‐sensitive lipid (YSK05) results in a dramatic improvement in silencing efficiency by enhancing endosomal escape, but this also causes a reduction in the lung selectivity. Contrary to the assumption that active targeting is largely dependent on the presence of a targeting ligand, the findings of the present study indicate that nanocarrier composition is critical for achieving the organ selectivity. Interestingly, helper lipids substantially mask the liver delivery resulting in optimum lung targeting. The optimized YSK05‐MEND is 40‐fold more efficient than a previously developed MEND, with a robust lung endothelium gene knockdown at small doses. The YSK05‐MEND strongly inhibits a metastatic lung cancer model and exerts superior control over lung metastasis compared to chemotherapy or the previously developed MEND. The YSK05‐MEND is well‐tolerated in mice after acute or chronic administration. As far as it is known, YSK05‐MEND achieves the most efficient lung endothelium gene silencing reported thus far with a median effective dose of 0.01 mg siRNA kg−1 while minimally affecting the endothelium of other organs.
A α-helical GALA peptide (WEAALAEALAEALAEHLAEALAEALEALAA) has been found to possess dual functions: a pH-dependent inducer of endosomal escape, and a ligand that targets lung endothelium. In the present study, the flexibility of GALA was improved by modifying the edge with polyethylene glycol linker, to increase lung-targeting activity. We first investigated the uptake of the GALA-modified liposomes in which GALA was directly conjugated to the lipid (Cholesterol: GALA/Chol) or the phospholipid-PEG (GALA/PEG). The liposomes that were modified with GALA/PEG (GALA/PEG-LPs) were taken up at a higher level by human lung endothelial cells (HMVEC-L), in comparison with particles that were modified with GALA/Chol (GALA/Chol-LPs). Small-interfering RNA-encapsulating liposomal-based nanocarriers (multifunctional envelope-type nano device: MEND) that were formulated with a vitamin E-scaffold SS-cleavable pH-activated lipid-like material, namely GALA/PEG-MEND were also modified with GALA/PEG. Gene silencing activity in the lung endothelium was then evaluated against an endothelial marker; CD31. In comparison with the unmodified MEND, GALA/PEG-MEND exhibited a higher silencing activity in the lung. Optimization of GALA/PEG-MEND resulted in silencing activity in the lung with an ED value of 0.21 mg/kg, while non-specific gene silencing in liver was marginal. Collectively, PEGylated GALA is a promising device for use in targeting the lung endothelium.
This study describes the development of lipid nanoparticles (LNPs) for the efficient and selective delivery of plasmid DNA (pDNA) to the lungs. The GALA peptide was used as a ligand to target the lung endothelium and as an endosomal escape device. Transfection activity in the lungs was significantly improved when pDNA was encapsulated in double-coated LNPs. The inner coat was composed of dioleoylphsophoethanolamine and a stearylated octaarginine (STR-R8) peptide, while the outer coat was largely a cationic lipid, di-octadecenyl-trimethylammonium propane, mixed with YSK05, a pH-sensitive lipid, and cholesterol. Optimized amounts of YSK05 and GALA were used to achieve an efficient and lung-selective system. The optimized system produced a high gene expression level in the lungs (>10 7 RLU/mg protein) with high lung/liver and lung/spleen ratios. GALA/R8 modification and the double-coating design were indispensable for efficient gene expression in the lungs. Despite the fact that NPs prepared with 1-step or 2-step coating have the same lipid amount and composition and the same pDNA dose, the transfection activity was dramatically higher in the lungs in the case of 2-step coating. Surprisingly, 1-step or 2-step coatings had no effect on the amount of nanoparticles that were delivered to the lungs, suggesting that the double-coating strategy substantially improved the efficiency of gene expression at the intracellular level.
19We previously reported that a multifunctional envelope-type nano device (MEND) modified with a 20 GALA peptide (GALA/MEND) exerted dual functions; effective targeting the pulmonary 21 endothelium and endosomal escape. The GALA/MEND containing encapsulated siRNA was originally 22 prepared by the film coated hydration method (GALA/MEND Hyd ). However, an ethanol dilution method 23 was found to be appropriate for scaling up the preparation of this liposomal nanoparticle. In this 24 study, we report on the preparation of a GALA/MEND based on the principal of the ethanol dilution 25
The use of polyethylene glycol (PEG)-modified lipids (PEGlipids) as a component of cationic liposomes impairs the cytoplasmic delivery of the encapsulated cargos by reducing endosomal escape. While this results in a loss of gene expression of encapsulated plasmid DNA, PEG-modification is useful in that it permits the formation of small, stabilized particles. In the present study, the dilemma associated with the use of PEG was overcome by modifying liposomes with stearylated INF7 (STR-INF7), a membrane fusion-independent destabilizer of endosomes, and substituting hydrophobic lipid-anchors in the PEG-lipid. The cationic liposomes modified with a series of PEG-lipids showed a drastically impaired transgene expression. However, the incorporation of STR-INF7 recovered the gene expression, and this was found to be mainly dependent on the type of PEG lipid-anchor used. Of note, the fold increase in transfection activity was highest in cholesterolanchored PEG (>100-fold), whose enhanced endosomal escape was followed by imaging techniques. These data suggest that the structure of lipid-anchors in PEG affects the action of the peptides for inducing of endosomal escape.
Serum proteins affect the in vivo fate and cellular uptake of arginine-rich cell-penetrating peptides (CPPs) and drugs delivered by CPPs. Although the binding of CPPs to serum proteins may possibly reduce their cellular uptake to some extent, it may also prolong their circulation half-life in vivo. We aimed to identify novel binding proteins of arginine-rich CPPs in serum to better understand their in vivo fate and develop more sophisticated drug delivery systems using CPPs. Isothermal titration calorimetry analysis suggests that albumin, the most abundant protein in serum, binds to D-forms of oligoarginine; however, the dissociation constants are several tens of a micromolar. Candidate proteins with the potential of binding to arginine-rich CPPs in serum were then explored using nondenaturing polyacrylamide gel electrophoresis followed by mass spectrometry analysis. Studies using fluorescence correlation spectroscopy determined hemopexin as a potential binding partner of D-forms of arginine-rich CPPs, including D-octaarginine (r 8 ) and the D-form of the peptide, corresponding to HIV-1 Rev (34−50), with dissociation constants of submicromolar to micromolar range. Using flow cytometry and a split-luciferase-based system, the promotion effect of hemopexin on the total cellular uptake and cytosolic localization of cargos conjugated with these CPPs was confirmed. Therefore, this study elucidated hemopexin as a potential binding partner of D-arginine-rich CPPs that may affect their in vivo fate and cellular uptake.
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