Stabilized plasmid–lipid particles containing PEG-diacylglycerols exhibit extended circulation lifetimes and tumor selective gene expression

Abstract

Stabilized plasmid lipid particles (SPLP) consist of a single copy of DNA surrounded by a lipid bilayer. The particles are small ( approximately 100 nm), stable, monodisperse and have a low surface charge. A diffusible polyethylene glycol (PEG) coating attached to a lipid anchor is critical to the SPLP's functionality. The PEG-lipid exchanges out of the bilayer at a rate determined by the size of the lipid anchor. Here we show that SPLP can be prepared using a series of PEG-diacylglycerol lipids (PEG-S-DAGs). SPLP were prepared incorporating PEG-dimyristoylglycerol (C14), PEG-dipalmitoylglycerol (C16) or PEG-distearoylglycerol (C18) and the rate of PEG-lipid diffusion from the bi-layer determined using a FRET assay. SPLP pharmacokinetics confirm a correlation between the stability of the PEG-lipid component and circulation lifetime. PEG-S-DAGs with longer lipid anchors yield more stable SPLP particles with longer circulation half-lives yielding an increase in tumor delivery and gene expression. PEG-distearoylglycerol (C18) containing SPLP bypass so-called 'first pass' organs, including the lung, and elicit levels of gene expression in distal tumor tissue 100- to 1000-fold greater than that observed in any other tissue. The incorporation of PEG-S-DAG in SPLP confirms that small size, low surface charge and extended circulation lifetimes are prerequisite to the accumulation and tumor selective expression of plasmid DNA following systemic administration.

A pH-sensitive cationic lipid facilitates the delivery of liposomal siRNA and gene silencing activity in vitro and in vivo

“…It is known that PEG lipid with a long acyl chain, such as PEG-DSG, is retained strongly by a lipid membrane while PEG lipid with short acyl chain, such as PEG-DMG, dissociated more readily from a membrane [28]. After the incorporation of PEG-DSG, the stability of the optimized YSK05-MEND in serum was significantly increased, as expected ( Supplementary Fig.…”

“…[27] reported that the pharmacokinetics of the lipid nanoparticles (LNPs) with an ionizable aminolipid, which is largely neutral but changes to a cationic form under acidic conditions, was improved compared to that with a conventional cationic lipid. The LNPs system also succeeded in tumor specific reporter gene expression, and gene silencing in orthotopic and subcutaneous tumors [28,29].…”

Development of a novel systemic gene delivery system for cancer therapy with a tumor-specific cleavable PEG-lipid

“…To improve the stability in the systemic circulation and the tumor accumulation, various groups have devised non-viral gene carriers with PEG. [13][14][15][16][17][18][19][30][31][32] Recently, cleavable PEG systems were developed, which are cleaved in response to an intracellular environment (e.g. low pH in endosome/ lysosomes, thiolytically small molecules, etc.…”

“…To resolve this dilemma, various devices have been developed. Ambegia et al 13 developed a strategy of exchangeable PEG-lipids. In the present study, we propose alternative strategy, involving a novel gene delivery system for cancer gene therapy, using a MEND modified with a tumor -specifically cleavable PEG-lipid.…”

siRNA Lipid Nanoparticle Potently Silences Clusterin and Delays Progression When Combined with Androgen Receptor Cotargeting in Enzalutamide-Resistant Prostate Cancer

“…Although preclinical studies in prostate cancer (16) and immune cells (17) are promising, distant tumor delivery has not been tested in the clinic. In order to mitigate this higher Peg-lipid content is used to improve the pharmacodynamic and biodistribution of LNP systems to the tumor site (18)(19)(20).…”