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Leon, Lorraine

Publications and source records attributed to Leon, Lorraine.

Targeted polyelectrolyte complex micelles treat vascular complications in vivo

Vascular disease is a leading cause of morbidity and mortality in the United States and globally. Pathological vascular remodeling, such as atherosclerosis and stenosis, largely develop at arterial sites of curvature, branching, and bifurcation, where disturbed blood flow activates vascular endothelium. Current pharmacological treatments of vascular complications principally target systemic risk factors. Improvements are needed. We previously devised a targeted polyelectrolyte complex micelle to deliver therapeutic nucleotides to inflamed endothelium in vitro by displaying the peptide VHPKQHR targeting vascular cell adhesion molecule 1 (VCAM-1) on the periphery of the micelle. This paper explores whether this targeted nanomedicine strategy effectively treats vascular complications in vivo. Disturbed flow-induced microRNA-92a (miR-92a) has been linked to endothelial dysfunction. We have engineered a transgenic line (miR-92a EC-TG /Apoe –/– ) establishing that selective miR-92a overexpression in adult vascular endothelium causally promotes atherosclerosis in Apoe –/– mice. We tested the therapeutic effectiveness of the VCAM-1–targeting polyelectrolyte complex micelles to deliver miR-92a inhibitors and treat pathological vascular remodeling in vivo. VCAM-1–targeting micelles preferentially delivered miRNA inhibitors to inflamed endothelial cells in vitro and in vivo. The therapeutic effectiveness of anti–miR-92a therapy in treating atherosclerosis and stenosis in Apoe –/– mice is markedly enhanced by the VCAM-1–targeting polyelectrolyte complex micelles. These results demonstrate a proof of concept to devise polyelectrolyte complex micelle-based targeted nanomedicine approaches treating vascular complications in vivo.

60 APPLIED LIFE SCIENCES↗

Structure–Property Relationships of Oligonucleotide Polyelectrolyte Complex Micelles

Polyelectrolyte complex micelles (PCMs), nanoparticles formed by electrostatic self-assembly of charged polymers with charged-neutral hydrophilic block copolymers, offer a potential solution to the challenging problem of delivering therapeutic nucleic acids into cells and organisms. Promising results have been reported in vitro and in animal models but basic structure property relationships are largely lacking, and some reports have suggested that double stranded nucleic acids cannot form PCMs due to their high bending rigidity. Here, we report on a study of PCMs formed by DNA oligonucleotides of varied length and hybridization state and poly(L)lysine-poly(ethylene glycol) block copolymers with varying block lengths. We employ a multimodal characterization strategy combining small-angle X-ray scattering (SAXS), multiangle light scattering (MALS), and cryo-electron microscopy (cryo-TEM) to simultaneously probe the morphology and internal structure of the micelles. Over a wide range of parameters, we find that nanoparticle shape is controlled primarily by the hybridization state of the oligonucleotides with single-stranded oligonucleotides forming spheroidal micelles and double stranded oligonucleotides forming wormlike micelles. The length of the charged block controls the radius of the nanoparticle, while oligonucleotide length appears to have little impact on either size or shape. At smaller length scales, we observe parallel packing of DNA helices inside the double-stranded nanoparticles, consistent with results from condensed genomic DNA. We additionally describe salt- and thermal-annealing protocols for preparing PCMs with high repeatability and low polydispersity. Together, these results provide a capability to rationally design PCMs with desired sizes and shapes that should greatly assist development of this promising delivery technology.

77 NANOSCIENCE AND NANOTECHNOLOGY↗

Oligonucleotide–Peptide Complexes: Phase Control by Hybridization

When oppositely charged polymers are mixed, counterion release drives phase separation; understanding this process is a key unsolved problem in polymer science and biophysical chemistry, particularly for nucleic acids, polyanions whose biological functions are intimately related to their high charge density. In the cell, complexation by basic proteins condenses DNA into chromatin, and membraneless organelles formed by liquid-liquid phase separation of RNA and proteins perform vital functions and have been linked to disease. Electrostatic interactions are also the primary method used for assembly of nanoparticles to deliver therapeutic nucleic acids into cells. This paper describes complexation experiments with oligonucleotides and cationic peptides spanning a wide range of polymer lengths, concentrations, and structures, including RNA and methylphosphonate backbones. We find that the phase of the complexes is controlled by the hybridization state of the nucleic acid, with double-stranded nucleic acids forming solid precipitates while single-stranded oligonucleotides form liquid coacervates, apparently due to their lower charge density. Adding salt "melts" precipitates into coacervates, and oligonucleotides in coacervates remain competent for sequence-specific hybridization and phase change, suggesting the possibility of environmentally responsive complexes and nanoparticles for therapeutic or sensing applications.

36 MATERIALS SCIENCE↗