Magali Noiray

Versatile and Efficient Targeting Using a Single Nanoparticulate Platform: Application to Cancer and Alzheimer's Disease

A versatile and efficient functionalization strategy for polymeric nanoparticles (NPs) has been reported and successfully applied to PEGylated, biodegradable poly(alkyl cyanoacrylate) (PACA) nanocarriers. The relevance of this platform was demonstrated in both the fields of cancer and Alzheimers disease (AD). Prepared by copper-catalyzed azide-alkyne cycloaddition (CuAAC) and subsequent self-assembly in aqueous solution of amphiphilic copolymers, the resulting functionalized polymeric NPs exhibited requisite characteristics for drug delivery purposes: (i) a biodegradable core made of poly(alkyl cyanoacrylate), (ii) a hydrophilic poly(ethylene glycol) (PEG) outer shell leading to colloidal stabilization, (iii) fluorescent properties provided by the covalent linkage of a rhodamine B-based dye to the polymer backbone, and (iv) surface functionalization with biologically active ligands that enabled specific targeting. The construction method is very versatile and was illustrated by the coupling of a small library of ligands (e.g., biotin, curcumin derivatives, and antibody), resulting in high affinity toward (i) murine lung carcinoma (M109) and human breast cancer (MCF7) cell lines, even in a coculture environment with healthy cells and (ii) the β-amyloid peptide 1-42 (Aβ(1-42)), believed to be the most representative and toxic species in AD, both under its monomeric and fibrillar forms. In the case of AD, the ligand-functionalized NPs exhibited higher affinity toward Aβ(1-42) species comparatively to other kinds of colloidal systems and led to significant aggregation inhibition and toxicity rescue of Aβ(1-42) at low molar ratios.

Peptide-functionalized nanoparticles for selective targeting of pancreatic tumor.

Chemotherapy for pancreatic cancer is hampered by the tumors physio-pathological complexity. Here we show a targeted nanomedicine using a new ligand, the CKAAKN peptide, which had been identified by phage display, as an efficient homing device within the pancreatic pathological microenvironment. Taking advantage of the squalenoylation platform, the CKAAKN peptide was conjugated to squalene (SQCKAAKN) and then co-nanoprecipitated with the squalenoyl prodrug of gemcitabine (SQdFdC) giving near monodisperse nanoparticles (NPs) for safe intravenous injection. By interacting with a novel target pathway, the Wnt-2, the CKAAKN functionalization enabled nanoparticles: (i) to specifically interact with both tumor cells and angiogenic vessels and (ii) to simultaneously promote pericyte coverage, thus leading to the normalization of the vasculature likely improving the tumor accessibility for therapy. All together, this approach represents a unique targeted nanoparticle design with remarkable selectivity towards pancreatic cancer and multiple mechanisms of action.

Poly(γ-benzyl-l-glutamate)-PEG-alendronate multivalent nanoparticles for bone targeting

Hydroxyapatite (HAP), a highly specific component of bone tissue, is the main target in order to impart osteotropicity. Bone targeted nanoparticles can increase the strength of the interaction with HAP through multivalency and thus constitute a valuable strategy in the therapeutics of skeletal diseases. PBLG10k-b-PEG6k-alendronate nanoparticles (~ 75 nm) were prepared by a simple nanoprecipitation method. The calcium affinity (KCa(+2)=1.8 × 10(4)M(-1)) of these nanoparticles was evaluated using isothermal titration calorimetry. The multivalent interaction with HAP surfaces (KHAP) was studied by fluorescence and was estimated to be 1.1 × 10(10)M(-1), which is more than 4000 times stronger than the reported monovalent interaction between alendronate and HAP surfaces. Molecular modeling suggests that the number of binding sites available at the HAP surface is in large excess than what is required for the whole surface coverage by alendronate decorated nanoparticles. The lower calcium affinity of these nanoparticles than for HAP allows calcium bound nanoparticles to interact with HAP, which yields a deeper understanding of bone targeted carriers and could potentially improve their bone targeting properties.

Supramolecular Organization and siRNA Binding of Hyaluronic Acid-Coated Lipoplexes for Targeted Delivery to the CD44 Receptor

The dynamics of the formation of siRNA-lipoplexes coated with hyaluronic acid (HA) and the parameters influencing their supramolecular organization were studied. The insertion of a HA-dioleylphosphatidylethanolamine (DOPE) conjugate in the liposome structure as well as subsequent complexation with siRNA increased the liposome size. Lipoplexes were around 110 nm at high ± charge ratios with a zeta potential around +50 mV and around 230 nm at low ± ratios, with a zeta potential that decreased to negative values, reaching -45 mV. The addition of the conjugate did not compromise siRNA binding to liposomes, although these nucleic acids induced a displacement of part of the HA-DOPE conjugate upon lipoplex formation, as confirmed by capillary electrophoresis. Isothermal titration calorimetry, X-ray diffraction studies, and cryo-TEM microscopy demonstrated that in addition to electrostatic interactions with siRNA a rearrangement of the lipid bilayers takes place, resulting in condensed oligolamellar vesicles. This phenomenon is dependent on the number of siRNA molecules and the degree of modification with HA. Finally, the suitable positioning of HA on the lipoplex surface and its ability to bind specifically to the CD44 receptors in a concentration-dependent manner was demonstrated by surface plasmon resonance analysis.

Peptide conjugation: before or after nanoparticle formation?

We report herein a detailed study concerning the impact of different bioconjugation and nanoformulation strategies on the in vitro targeting ability of peptide-decorated squalenoyl gemcitabine (SQdFdC) nanoparticles (NPs). NPs have been functionalized with the CKAAKN peptide, previously identified as an efficient homing device within the pancreatic pathological microenvironment. Two approaches have been followed: (i) either the CKAAKN peptide was directly conjugated at the surface of preformed SQdFdC nanoparticles (conjugation after NP formation) or (ii) it was first reacted with a maleimide squalenoyl derivative before the resulting bioconjugate was co-nanoprecipitated with SQdFdC to form the peptide-decorated NPs (conjugation before NP formation). NPs were characterized with respect to mean diameter, zeta potential, and stability over time. Then, their specific interaction with the sFRP-4 protein was evaluated by surface plasmon resonance. Although both synthetic strategies allowed us to formulate NPs able to interact with the corresponding receptor, enhanced target binding and better specific avidity were observed with CKAAKN-NPs functionalized before NP formation. These NPs displayed the highest cell uptake and cytotoxicity in an in vitro model of human MIA Paca-2 pancreatic cancer cells.

Anti-Inflammatory Effect of Anti-TNF-α SiRNA Cationic Phosphorus Dendrimer Nanocomplexes Administered Intranasally in a Murine Acute Lung Injury Model

Inflammation is an essential component of many lung diseases, including asthma, chronic obstructive pulmonary disease (COPD), or acute lung injury. Our purpose was to design efficient carriers for lung delivery of small interfering RNA (siRNA) targeting tumor necrosis factor (TNF-α) in an acute lung injury model. To achieve this goal, two different types of phosphorus-based dendrimers with either pyrrolidinium or morpholinium as terminal protonated amino groups were selected for their better biocompatibility compared to other dendrimers. Dendriplexes containing pyrrolidinium surface groups demonstrated a stronger siRNA complexation, a higher cellular uptake, and enhanced in vitro silencing efficiency of TNF-α in the lipopolysaccharide (LPS)-activated mouse macrophage cell line RAW264.7, compared to morpholinium-containing dendriplexes. The better performance of the pyrrolidium dendriplexes was attributed to their higher pKa value leading to a stronger siRNA complexation and improved protection against enzymatic degradation resulting in a higher cellular uptake. The superior silencing effect of the pyrrolidinium dendriplexes, compared to noncomplexed siRNA, was confirmed in vivo in an LPS-induced murine model of short-term acute lung injury upon lung delivery via nasal administration. These data suggest that phosphorus dendriplexes have a strong potential in lung delivery of siRNA for treating inflammatory lung diseases.