Développement et caractérisation in vivo de nanoparticules lipidiques biocompatibles au moyen des techniques d'imagerie de fluorescence et nucléaire

La nanomédecine est un secteur d activité en plein essor depuis le développement des liposomes, nanovecteurs permettant d encapsuler des molécules hydrosolubles ou amphiphiles pour la délivrance de médicament. Les nouveaux agents thérapeutiques synthétisés étant de plus en plus lipophiles, le développement de nouveaux vecteurs nanoparticulaires permettant leur transport constitue aujourd hui un enjeu majeur. Les lipidots, nanoparticules lipidiques solides biocompatibles de 50 nm de diamètre, composées d un mélange d huile, de cire et de lécithine stabilisées par une couronne de surfactants pegylés, permettent de transporter des composés hautement hydrophobes en leur cœur. Des agents nucléaires pour la tomographie à émission monophotonique et des agents de fluorescence ont pu y être encapsulés pour l évaluation de la biodistribution de ces nanoparticules chez la souris saine ainsi que dans différents modèles tumoraux. Un peptide de ciblage, le cRGD a également été greffé à la surface des lipidots afin d adresser préférentiellement, dans les 3 premières heures après injection, les nanoparticules vers les tumeurs surexprimant les intégrines avb3. Une biodistribution particulière des lipidots dans les organes stéroïdiens (surrénales, ovaires) a été observée avec une localisation spécifique dans les zones synthétisant les hormones stéroïdiennes (le corps jaune pour les ovaires, la zone corticale pour les surrénales). Cette affinité unique a été mise à projet pour cibler des tumeurs hormono-dépendantes, ainsi que pour encapsuler des hormones ovariennes pour le traitement hormonal substitutif ou le contrôle de la procréation.Nanomedicine is a fast growing field since the development of liposomes, nanovectors able to encapsulate in their core or phospholipid bilayer hydrophilic or amphiphilic molecules for drug delivery purposes. Nowadays, most of the new synthetized therapeutic compounds are hydrophobic, necessitating the development of new types of nanocargos. Lipidots, 50 nm diameter biocompatible solid lipid nanoparticles, composed of a mixture of oil, wax and lecithin stabilized by a shell of pegylated surfactants, are used to encapsulate highly hydrophobic compounds in their core for vectorization purpose. Nuclear agents for simple photon emission tomography, or near infrared fluorescent dyes, have been encapsulated in the lipidot core, to assess the biodistribution of these nanoparticles in healthy mice as well as in a large range of tumor models. A targeting peptide, the cRGD motif, was also grafted on the surface of lipidots to vectorize preferentially the nanoparticles to tumors overexpressing avb3 integrins. An unexpected lipidot biodistribution in steroid organs (adrenal, ovary) was observed, with a specific localization in areas of steroid hormones synthesis (corpus luteum in ovaries, cortex for adrenals). This unique lipidot affinity was used to target hormono-dependent cancer cells, as well as to encapsulate ovarian hormones, like estradiol or ethynil estradiol, for hormone substitution therapy or birth control.PARIS5-Bibliotheque electronique (751069902) / SudocPARIS-BIUM-Bib. électronique (751069903) / SudocSudocFranceF

Compact and highly stable quantum dots through optimized aqueous phase transfer

International audienceA large number of different approaches for the aqueous phase transfer of quantum dots have been proposed. Surface ligand exchange with small hydrophilic thiols, such as L-cysteine, yields the lowest hydrodynamic diameter. However, cysteine is prone to dimer formation, which limits colloidal stability. We demonstrate that precise pH control during aqueous phase transfer dramatically increases the colloidal stability of InP/ZnS quantum dots. Various bifunctional thiols have been applied. The formation of disulfides, strongly diminishing the fluorescence QY has been prevented through addition of appropriate reducing agents. Bright InP/ZnS quantum dots with a hydrodynamic diameter <10 nm and longterm stability have been obtained. Finally we present in vitro studies of the quantum dots functionalized with the cellpenetrating peptide maurocalcin

Resorbable conductive materials for optimally interfacing medical devices with the living

Implantable and wearable bioelectronic systems are arising growing interest in the medical field. Linking the microelectronic (electronic conductivity) and biological (ionic conductivity) worlds, the biocompatible conductive materials at the electrode/tissue interface are key components in these systems. We herein focus more particularly on resorbable bioelectronic systems, which can safely degrade in the biological environment once they have completed their purpose, namely, stimulating or sensing biological activity in the tissues. Resorbable conductive materials are also explored in the fields of tissue engineering and 3D cell culture. After a short description of polymer-based substrates and scaffolds, and resorbable electrical conductors, we review how they can be combined to design resorbable conductive materials. Although these materials are still emerging, various medical and biomedical applications are already taking shape that can profoundly modify post-operative and wound healing follow-up. Future challenges and perspectives in the field are proposed

Récipients périssables en contexte de crémation : apport de la tomodensitométrie

International audienceDes contenants en matériau périssable sont fréquemment utilisés pour déposer dans une sépulture, les os d’un corps incinéré. Le phénomène concerne toutes les étapes de l’âge du Bronze et se poursuit au­delà. Cet usage est d’ailleurs une des constantes funéraires observées dans la moitié nord­-est de la France, tout au long de La Tène et de l’Antiquité. Ce travail propose un retour d’expériences centrées sur la détection et l’identification de récipients organiques utilisés en contexte crématoire. Nous avons testé l’intégration des images tomographiques dans les protocoles de fouille et d’enregistrement d’un dépôt cinéraire afin d’en évaluer les apports et les enjeux. Les deux cas d’étude présentés sont datés de l’âge du Bronze moyen et s’insèrent dans le projet ANR « Introspection du mobilier archéologique à l’ère numérique ». Ce dernier s’intéresse aux méthodes d’introspection numérique interactive en combinant la tomodensitométrie avec des technologies de visualisation 3D : réalité virtuelle, interactions tangibles et impression 3D

Quantification of surface GalNAc ligands decorating nanostructured lipid carriers by UPLC-ELSD

Nanoparticles have been extensively studied for drug delivery and targeting to specific organs. The functionalization of the nanoparticle surface by site-specific ligands (antibodies, peptides, saccharides) can ensure efficient recognition and binding with relevant biological targets. One of the main challenges in the development of these decorated nanocarriers is the accurate quantification of the amount of ligands on the nanoparticle surface. In this study, nanostructured lipid carriers (NLC) were functionalized with N-acetyl-D-galactosamine (GalNAc) units, known to target the asialoglycoprotein receptor (ASGPR). Different molar percentages of GalNAc-functionalized surfactant (0%, 2%, 5%, and 14%) were used in the formulation. Based on ultra-high-performance liquid chromatography separation and evaporative light-scattering detection (UPLC-ELSD), an analytical method was developed to specifically quantify the amount of GalNAc units present at the NLC surface. This method allowed the accurate quantification of GalNAc surfactant and therefore gave some insights into the structural parameters of these multivalent ligand systems. Our data show that the GalNAc decorated NLC possess large numbers of ligands at their surface and suitable distances between them for efficient multivalent interaction with the ASGPR, and therefore promising liver-targeting efficiency

Novel nanostructured lipid carriers dedicated to nucleic acid delivery for RNAi purposes

International audienceThe specific down-regulation triggered through interference RNA (RNAi) provides a means to determine the gene functions and their contributions in an altered phenotype. In this way, high throughput screening (HTS) has emerged as a potent automated tool to study a large number of genes for identification of new biomarkers and therapeutic targets. However, the siRNA-mediated gene knock down requires that siRNA can reach cytoplasm compartment where RNAi occurs. Unfortunately, the siRNA is relatively vulnerable in the extracellular environment due to the presence of degradation enzymes and its high molecular weight associated to its anionic charge limit considerably its cell incorporation across the plasma membrane. Thereby, HTS requires generic carriers with highly efficient siRNA transfection. To overcome these obstacles, multifunctional nanoparticles comprising an imaging contrast agent are emerging as an original and promising approach in the improved, controlled and monitored delivery of siRNA

In vitro and in vivo intracellular delivery of quantum dots by maurocalcine

International audienceMaurocalcine is a new member of the increasing family of cell penetrating peptides. We report for the first time that this peptide is able to deliver quantum dots inside a variety of cells, both in vitro and in vivo. In vivo, maurocalcine produces intracellular delivery of the nanoparticles without affecting the relative distribution of quantum dots within organs. The data stress out that maurocalcine can be used for intracellular delivery of functionalised nanoparticles in vivo

A whole-genome sequence and transcriptome perspective on HER2-positive breast cancers.

HER2-positive breast cancer has long proven to be a clinically distinct class of breast cancers for which several targeted therapies are now available. However, resistance to the treatment associated with specific gene expressions or mutations has been observed, revealing the underlying diversity of these cancers. Therefore, understanding the full extent of the HER2-positive disease heterogeneity still remains challenging. Here we carry out an in-depth genomic characterization of 64 HER2-positive breast tumour genomes that exhibit four subgroups, based on the expression data, with distinctive genomic features in terms of somatic mutations, copy-number changes or structural variations. The results suggest that, despite being clinically defined by a specific gene amplification, HER2-positive tumours melt into the whole luminal-basal breast cancer spectrum rather than standing apart. The results also lead to a refined ERBB2 amplicon of 106 kb and show that several cases of amplifications are compatible with a breakage-fusion-bridge mechanism

A whole-genome sequence and transcriptome perspective on HER2-positive breast cancers

HER2-positive breast cancer has long proven to be a clinically distinct class of breast cancers for which several targeted therapies are now available. However, resistance to the treatment associated with specific gene expressions or mutations has been observed, revealing the underlying diversity of these cancers. Therefore, understanding the full extent of the HER2-positive disease heterogeneity still remains challenging. Here we carry out an in-depth genomic characterization of 64 HER2-positive breast tumour genomes that exhibit four subgroups, based on the expression data, with distinctive genomic features in terms of somatic mutations, copy-number changes or structural variations. The results suggest that, despite being clinically defined by a specific gene amplification, HER2-positive tumours melt into the whole luminal-basal breast cancer spectrum rather than standing apart. The results also lead to a refined ERBB2 amplicon of 106 kb and show that several cases of amplifications are compatible with a breakage-fusion-bridge mechanism