Molecular Tuning of a Vitamin E-Scaffold pH-Sensitive and Reductive Cleavable Lipid-like Material for Accelerated in Vivo Hepatic siRNA Delivery

Abstract

A lipid nanoparticle (LNP) composed of a series of SS-cleavable and pH-activated lipid-like materials (ssPalm) was previously developed as a platform of a gene delivery system. A tertiary amine and disulfide bonding were employed to destabilize the endosomal membrane and for intracellular collapse. We report herein on the development of a hepatocyte-targeting siRNA carrier by the molecular tuning of the hydrophobic scaffold, and tertiary amine structures. The gene knockdown activity against a hepatocyte-specific marker (factor VII: FVII) was improved when a more fat-soluble vitamin (vitamin E) was employed as a hydrophobic scaffold. Moreover, to allow the tertiary amines to accept protons by sensing a slight change in endosomal acidification, its structural flexibility was minimized by fixing it in a piperidine structure, and the distance between the surface of the particle to the ternary amine was increased. As a result, the pK a value was increased to the approximately 6.18 depending on its distance, while the pK a reached plateau when the tertiary amine was linked by an excess number of linear carbon chains. The pH-dependent membrane destabilization activity, as assessed by a hemolysis assay, was increased in parallel with the pK a value. Moreover, the gene knockdown activity was improved in parallel with hemolytic activity. Finally, further optimization of the lipid/siRNA ratio, and the use of chemically (2′-fluoro) modified siRNA synergistically improved the gene knockdown efficacy to an effective dose (ED 50 ) of 0.035 mg/kg. The developed ssPalm represents a promising platform for use as a hepatocyte-targeting siRNA carrier.

The delivery of mRNA to colon inflammatory lesions by lipid-nano-particles containing environmentally-sensitive lipid-like materials with oleic acid scaffolds

“…However, it is generally observed that LNPs modified with PEG-lipids containing shorter fatty acid scaffolds (i.e. dimyristoyl scaffold; PEG-DMG) dominantly accumulate in the liver, when the particles are administrated via the tail vein since the shorter PEG-lipids can easily dissociate from the particles in the blood circulation [ 6 , 14 , 15 , 16 ]. Since a longer blood retention is a crucial driving force for delivering LNP ssPalm to an inflammatory lesion, the LNP ssPalms used in the present study were modified with PEG-lipids that contain a longer chain fatty acid (distearoyl scaffold; PEG-DSG) that would allow the particles to be retained for longer periods of time in the blood.…”

Methods for Evaluating the Stimuli-Responsive Delivery of Nucleic Acid and Gene Medicines

“…14) As to the delivery processes after intravenous administration, the first event for the vectors is interaction with blood components, including erythrocytes and plasma proteins. [15][16][17][18][19][20][21] In particular, interaction with plasma proteins is a determinant factor for tissue accumulation. [19][20][21][22] Interaction with plasma proteins is highly dependent on the composition of the vectors.…”

“…[15][16][17][18][19][20][21] In particular, interaction with plasma proteins is a determinant factor for tissue accumulation. [19][20][21][22] Interaction with plasma proteins is highly dependent on the composition of the vectors. The interaction of cationic liposome (1,2-dioleoyl-3-trimethylammoniumpropane (DOTAP)/cholesterol)/plasmid DNA complex with fibronectin contributes to lung accumulation and gene expression after intravenous administration.…”

“…20) Ionizable lipid nanoparticles containing siRNA interact with apolipoprotein E, and subsequently accumulates in the liver. 21,22) After interaction with blood components, the vectors are distributed to tissues throughout the body through systemic circulation. Thus, targeting strategies are required to deliver vectors to a specific tissue.…”

Innovative Technologies in Nanomedicines: From Passive Targeting to Active Targeting/From Controlled Pharmacokinetics to Controlled Intracellular Pharmacokinetics

“…For example, LNP ssPalmA can share the nuclear transport system of vitamin A for nuclear accumulation . The other example is that the LNP ssPalmE confers extensive hepatic accumulation mainly due to the surface binding of ApoE, followed by uptake into the liver via LDL receptors . The character of ApoE‐dependent uptake is also useful for the targeting of brain associated cells such astrocytes, since these cells also express LDL receptor families, and play a key role in the mutual transfer of lipoproteins.…”