Research & Development

R&D : Publications

The vaxinano's technology centers on a unique and innovative antigen delivery system exploiting safe-by-design, adjuvant-free and biocompatible nanoparticles. A selection of major scientific publications are listed below.

Nasal Nanovaccines


International Journal of Pharmaceutics - 2017 Jul 8;530(1-2):128-138

Author: Bernocchi B., Carpentier, R., Betbeder D.

Nasal administration of vaccines is convenient for the potential stimulation of mucosal and systemic immune protection. Moreover the easy accessibility of the intranasal route renders it optimal for pandemic vaccination. Nanoparticles have been identified as ideal delivery systems and adjuvants for vaccine application. Heterogeneous protocols have been used for animal studies. This complicates the understanding of the formulation influence on the immune response and the comparison of the different nanoparticles approaches developed. Moreover anatomical and immunological differences between rodents and humans provide an additional hurdle in the rational development of nasal nanovaccines. This review will give a comprehensive expertise of the state of the art in nasal nanovaccines in animals and humans focusing on the nanomaterial used.

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Synthetic parasites: a successful mucosal nanoparticle vaccine against Toxoplasma congenital infection in mice.


FUTURE MICROBIOLOGY Volume: 12 Pages 393-405

Author: Ducournau, C.; Nguyen, T.; Carpentier, R.; […] Betbeder, D.; Dimier-Poisson, I.

Aims: Development of protein vaccine to prevent congenital infection is a major public health priority. Our goal is the design of mucosal synthetic pathogen inducing protective immune responses against congenital toxoplasmosis.
Materials & Methods: Mice were immunized intranasally, establishing pregnancy and challenging orally. Placental immune response, congenital infection, pup growth, parasitic load rates were studied.
Results: Pups born to vaccinated infected dams had significantly fewer brain cysts, no intraocular inflammation and normal growth. Protection was associated with a placental cellular Th1 response down-regulated by IL-6 and correlated with persistence of vaccine for few hours in the nose before being totally eliminated.
Conclusion: Our vaccine conferred high protection against congenital toxoplasmosis. These results provide support for future studies of other congenital vaccine.

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Mechanisms allowing protein delivery in nasal mucosa using NPL nanoparticles.



Author: Bernocchi, B.; Carpentier, R.; Lantier, I.; Ducournau, C.; Dimier-Poisson, I.; Betbeder, D.

The intranasal administration of proteins using nanoparticles is a promising approach for several applications, especially for mucosal vaccines. Delivery of protein within the epithelial barrier is a key point to elicit an immune response and nano-carrier has to show no toxicity. The aim of this work was to elucidate the interactions of cationic porous nanoparticles loaded with protein delivery for antigen delivery in the nose. We investigated the loading, the cellular delivery and the epithelial transcytosis of proteins associated to these nanoparticles containing an anionic lipid in their core (NPL). NPL were highly endocytosed by airway epithelial cells and significantly improved the protein delivery into the cell. In vitro transcytosis studies showed that NPL did not modify the in vitro epithelial permeability suggesting no toxicity of these carriers. Moreover protein and NPL did not translocate the epithelial barrier. In vivo studies demonstrated that NPL prolonged the nasal residence time of the protein and no NPL were found beyond the epithelial barrier in vivo, precluding a negative side effect. All together these results establish the NPL as a bio-eliminable and optimal vaccine carrier.

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Porous nanoparticles as delivery system of complex antigens for an effective vaccine against acute and chronic Toxoplasma gondii infection


BIOMATERIALS Volume: 50 Pages: 164-175

Author: Dimier-Poisson, I.; Carpentier, R.; N'Guyen, T.; Dahmani, F.; Ducounau, C.; Betbeder, D.

Development of sub-unit mucosal vaccines requires the use of specific delivery systems or immune-modulators such as adjuvants to improve antigen immunogenicity. Nasal route for vaccine delivery by nanoparticles has attracted much interest but mechanisms triggering effective mucosal and systemic immune response are still poorly understood. Here we study the loading of porous nanoparticles (DGNP) with a total extract of Toxoplasma gondii antigens (TE), the delivery of TE by DGNP into airway epithelial, macrophage and dendritic cells, and the subsequent cellular activation. In vitro, DGNP are able to load complex antigens in a stable and quantitative manner. The outstanding amount of antigen association by DGNP is used to deliver TE in airway mucosa cells to induce a cellular maturation with an increased secretion of pro-inflammatory cytokines. Evaluation of nasal vaccine efficiency is performed in vivo on acute and chronic toxoplasmosis mouse models. A specific Th1/Th17 response is observed in vivo after vaccination with DGNP/TE. This is associated with high protection against toxoplasmosis regarding survival and parasite burden, correlated with an increased delivery of antigens by DGNP in airway mucosa cells. This study provides evidence of the potential of DGNP for the development of new vaccines against a range of pathogens.

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Airway delivery of peptides and proteins using nanoparticles


BIOMATERIALS Volume: 34 Issue: 2 Pages: 516-525

Author: Dombu, C.; Betbeder, D.

Delivery of peptides and proteins via the airways is one of the most exciting potential applications of nanomedicine. These macromolecules could be used for many therapeutic applications, however due to their poor stability in physiological medium and difficulties in delivering them across biological barriers, they are very difficult to use in therapy. Nanoparticulate drug delivery systems have emerged as one of the most promising technologies to overcome these limitations, owing mainly to their proven capacity to cross biological barriers and to enter cells in high yields, thus improving delivery of macromolecules. In this review, we summarize the current advances in nanoparticle designed for transmucosal delivery of peptides and proteins. Challenges that must be overcome in order to derive clinical benefits are also discussed.

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Influence of surface charge and inner composition of nanoparticles on intracellular delivery of proteins in airway epithelial cells


BIOMATERIALS Volume: 33 Issue: 35 Pages: 9117-9126

Author: Dombu, C.; Carpentier, R.; Betbeder, D.

The delivery of protein in the airway using nanoparticles (NP) is an emerging strategy that shows encouraging results in vivo for several applications. However, the mechanisms by which NP deliver proteins to the inside of cells remain poorly understood. In this study, we investigated the intracellular delivery of ovalbumin (OVA) in human airway cells by two porous cationic polysaccharides nanoparticles. These NP have the same surface charge density but differ in that their inner core contains either cationic or anionic charges (respectively: NP+ and DGNP+). Confocal microscopy showed a rapid uptake of both NP by human airway cells, followed by a significant accumulation in clathrin vesicles and early endosomes. Both NP were found to associate OVA in a quantitative manner, and this association was stable even in presence of serum proteins. We observed that the two NP greatly increased OVA uptake by human airway cells, meanwhile FRET studies using FITC-labelled NP and TRITC-labelled OVA showed a gradual release of OVA from NP within cells, and this was much faster with DGNP+ than NP+. These results were confirmed using OVA–DQ to follow OVA degradation fragments within cells. Both NP increased intracellular proteolysis of OVA, however DGNP+ facilitated OVA escape from endosomes. Studies with trypsin and pepsin at different pH strongly suggested that both NP can protect (in the extracellular medium) or promote (in acidic endosomes) protein proteolysis, depending on the environment. Interestingly, the mechanisms involved could be explained as a function of protein global charge at different pH. All these results confirm the importance of not only the surface charge but also the inner composition of NP in determining their efficacy as tools for the delivery of proteins to different cellular compartments.

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Study of serum interaction with a cationic nanoparticle: Implications for in vitro endocytosis, cytotoxicity and genotoxicity


INTERNATIONAL JOURNAL OF PHARMACEUTICS Volume: 423 Issue: 1 Special Issue: SI Pages: 37-44

Author: Merhi, M.; Dombu, C.; Brient, A.; Chang, J.; Platel, A.; Le Curieux, F.; Marzin, D.; Nesslany, F.; Betbeder, D.

We used well-characterized and positively charged nanoparticles (NP+) to investigate the importance of cell culture conditions, specifically the presence of serum and proteins, on NP+ physicochemical characteristics, and the consequences for their endocytosis and genotoxicity in bronchial epithelial cells (16HBE14o-). NP+ surface charge was significantly reduced, proportionally to NP+/serum and NP+/BSA ratios, while NP+ size was not modified. Microscopy studies showed high endocytosis of NP+ in 16HBE14o-, and serum/proteins impaired this internalization in a dose-dependent manner. Toxicity studies showed no cytotoxicity, even for very high doses of NP+. No genotoxicity was observed with classic comet assay while primary oxidative DNA damage was observed when using the lesion-specific repair enzyme, formamidopyrimidine DNA-glycosylase (FPG). The micronucleus test showed NP+ genotoxicity only for very high doses that cannot be attained in vivo. The low toxicity of these NP+ might be explained by their high exocytosis from 16HBE14o- cells. Our results confirm the importance of serum and proteins on nanoparticles endocytosis and genotoxicity.

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Characterization of endocytosis and exocytosis of cationic nanoparticles in airway epithelium cells.


NANOTECHNOLOGY Volume: 21 Issue: 35

Author: Dombu, C.; Kroubi, M.; Ribouche, R.; Matran, R.; Betbeder, D.

A major challenge of drug delivery using colloids via the airway is to understand the mechanism implied in their interactions with epithelial cells. The purpose of this work was to characterize the process of endocytosis and exocytosis of cationic nanoparticles (NPs) made of maltodextrin which were developed as a delivery system for antigens in vaccine applications. Confocal microscopy demonstrated that these NP are rapidly endocytosed after as little as 3 min incubation, and that the endocytosis was also faster than NP binding since most of the NPs were found in the middle of the cells around the nuclei. A saturation limit was observed after a 40 min incubation, probably due to an equilibrium becoming established between endocytosis and exocytosis. Endocytosis was dramatically reduced at 4 °C compared with 37 °C, or by NaN3 treatment, both results suggesting an energy dependent process. Protamine pretreatment of the cells inhibited NPs uptake and we found that clathrin pathway is implied in their endocytosis. Cholesterol depletion increased NP uptake by 300% and this phenomenon was explained by the fact that cholesterol depletion totally blocked NP exocytosis. These results suggest that these cationic NPs interact with anionic sites, are quickly endocytosed via the clathrin pathway and that their exocytosis is cholesterol dependent, and are similar to those obtained in other studies with viruses such as influenza.

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