Search

Background. Traumatic brain injury (TBI) is the main cause of disabilities over the industrialized countries. Cognitive decline appears in the chronic phase of the pathology consecutively to cellular and molecular processes. Here we described the use of KCC2, a neuronal-specific potassium-chloride transporters as potent biomarker to predict cognitive dysfunctions after TBI. Methods. Using neuronal and total exosomes collection from blood serum in control and TBI subjects we were able to anticipate the decline of cognitive performance. Results. After TBI, we observed a significative and persistant loss of KCC2 expression in the blood exosomes that is correlated to changes in network activity and cellular processes such as secondary neurogenesis. Also we correlated this KCC2 loss in expression to the appearance of the cognitive decline observed in mice and more particularly we correlate the KCC2 loss of expression to the appearance of the depressive-like behavior. Conclusion. According to our protocol, we were able to confirm our previous findings in agreement with the potential therapeutic effect of bumetanide in the prevention of the post traumatic depression after TBI, by restoring the KCC2 expression thus preventing the massive neuronal death of interneurons and the secondary neurogenesis effect observed in such model.

The prevalence of retinal disorders associated with visual impairment and blindness is increasing worldwide, while most of them remain without effective treatment. Pharmacological and molecular therapy development is hampered by the lack of effective drug delivery into the posterior segment of the eye. Among molecular approaches, RNA-interference (RNAi) features strong advantages, yet delivering it to the inner layer of the retina appears extremely challenging. To address this, we developed an original magnetic nanoparticles (MNPs)-based transfection method that allows the efficient delivery of siRNA in all retinal layers of rat adult retinas through magnetic targeting. To establish delivery of RNAi throughout the retina, we have chosen organotypic retinal explants as an ex vivo model and for future high content screening of molecular drugs. Conversely to classic Magnetofection, and similar to conditions in the posterior chamber of the eye, our methods allows attraction of siRNA complexed to MNPs from the culture media into the explant. Our method termed "Reverse Magnetofection" provides a novel and nontoxic strategy for RNAi-based molecular as well as gene therapy in the retina that can be transferred to a wide variety of organ explants.

The use of synthetic RNA for research purposes as well as RNA-based therapy and vaccination has gained increasing importance. Given the anatomical seclusion of the eye, small interfering RNA (siRNA)-induced gene silencing bears great potential for targeted reduction of pathological gene expression that may allow rational treatment of chronic eye diseases in the future. However, there is yet an unmet need for techniques providing safe and efficient siRNA delivery to the retina. We used magnetic nanoparticles (MNPs) and magnetic force (Reverse Magnetofection) to deliver siRNA/MNP complexes into retinal explant tissue, targeting valosin-containing protein (VCP) previously established as a potential therapeutic target for autosomal dominant retinitis pigmentosa (adRP). Safe and efficient delivery of VCP siRNA was achieved into all retinal cell layers of retinal explants from the RHO P23H rat, a rodent model for adRP. No toxicity or microglial activation was observed. VCP silencing led to a significant decrease of retinal degeneration. Reverse Magnetofection thus offers an effective method to deliver siRNA into retinal tissue. Used in combination with retinal organotypic explants, it can provide an efficient and reliable preclinical test platform of RNA-based therapy approaches for ocular diseases.

Small interfering RNA (siRNA) is an important RNA interference tool that has found significant application in ocular therapy. For this reason, there is a considerable demand of siRNA delivery platforms able to effectively transfect cells within the retina. Up to now several strategies have been investigated for this application such as lipids, nanoparticles and polymers but in all the cases invasive injections are the only administration routes explored. Moreover, a major limitation shared by all these delivery systems is the lack of active targeting toward the posterior segment of the eye that hampers high transfection efficiencies.

The development of an innovative drug delivery system to target, after topical administration, the retina with bioactive agents against retinal pathologies is a major challenge. Currently, the sole approach to target these tissues is through intravitreous injection, but this is not free from problematics such as severe side effects and rapid clearance of small molecules from the vitreous.We aim to synthesize, develop and formulate a new magnetic nanoparticle‐mediated delivery technology that shall allow achieving needle‐free, anesthesia‐free delivery of active drugs to the retina after topical administration assisted by magnetic targeting.

Advances in RNA technology during the past two decades have led to the construction of replication-competent RNA, termed replicons, RepRNA, or self-amplifying mRNA, with high potential for vaccine applications. Cytosolic delivery is essential for their translation and self-replication, without infectious progeny generation, providing high levels of antigen expression for inducing humoral and cellular immunity. Synthetic nanoparticle-based delivery vehicles can both protect the RNA molecules and facilitate targeting of dendritic cells—critical for immune defense development. Several cationic lipids were assessed, with RepRNA generated from classical swine fever virus encoding nucleoprotein genes of influenza A virus. The non-cytopathogenic nature of the RNA allowed targeting to dendritic cells without destroying the cells—important for prolonged antigen production and presentation. Certain lipids were more effective at delivery and at promoting translation of RepRNA than others. Selection of particular lipids provided delivery to dendritic cells that resulted in translation, demonstrating that delivery efficiency could not guarantee translation. The observed translation in vitro was reproduced in vivo by inducing immune responses against the encoded influenza virus antigens. Cationic lipid-mediated delivery shows potential for promoting RepRNA vaccine delivery to dendritic cells, particularly when combined with additional delivery elements. Keywords: replicon, RepRNA, self-amplifying, cationic lipids, dendritic cells, nanoparticle delivery, influenza vaccines, humoral immunity, cellular immunity

International audience; Background: Gene delivery within the central nervous system at postnatal age is one of the most challenging tasks in neuroscience and currently only a few effective methods are available. Comparison with existing methods: For postnatal central nervous system cells, viral approaches are commonly used for genetic engineering but they face several biosafety requirements for production and use making them less accessible to the community. Conversely, lipid-based methods are widely used in cell culture but face limitation in vivo mainly due to the inflammatory responses they induce. To this aspect, the use of a transgenic mouse line can represent a credible answer to the community working on rat models still requires an effective and successful solution to circumvent these difficulties. New method: We describe a new polymer-based gene delivery system allowing persistent and robust in vivo transfection with low DNA amount, reduced inflammation and high diffusion. The expression profile along the brain, the stability, the diffusion of the DNA together with the quantity of cells transfected were evaluated through in vivo approaches. Results: With a single low-volume injection, we targeted different cell types within the rat brain. We measured the diffusion rate ranging from 1 to 5 mm based on the injected volume, in the three-dimensions axis. Finally, we modified brain susceptibility to epileptic seizures using a specific knock-down of the neuronal specific potassium chloride transporter 2. Conclusions: This safe and easy system opens perspectives for non viral gene delivery in the rat brain with perspectives to study brain function in vivo.

Microglia, the resident phagocytic cells of the brain, have recently been the subject of intense investigation given their role in pathology and normal brain physiology. In general, phagocytic cells are hard to transfect with plasmid DNA. The BV2 cell line is a murine cell line of microglial origin which is often used to study this cell type in vitro. Unfortunately, this microglial cell line is, like other phagocytic cells, resistant to transfection.Magnetofection is a well-established transfection method that combines DNA with magnetic particles which, under the influence of a magnetic field, ensures a high concentration of particles in proximity of cultured cells. Only recently, Glial-Mag was specifically developed for efficient transfection of microglia and microglial cell lines.Magnetofection with Glial-Mag yielded a transfection efficiency of 34.95% in BV2 cells, 24h after transfection with an eGFP-expressing plasmid. Efficient gene delivery caused a modest and short-lived cell activation (as measured by IL6 secretion) that ceased by 24h after transfection.Here we show that Glial-Mag magnetofection of BV2 cells yielded a significantly higher transfection efficiency (34.95%) compared to other chemical transfection methods including calcium-phoshate precipication (0.34%), X-tremeGENE (3.30%) and Lipofectamine 2000 (12.51%).Transfection of BV2 cells using Glial-Mag magnetofection is superior compared to other chemical transfection methods and could be considered as the method of choice to chemically transfect microglial cell lines.