Venue: CARF
Defense in french
Camille Ruffier
NutriNeuro
Title
Development of photoactivable polymersomes for temporal et spatial control of molecular delivery into the brain
Abstract
Many neurological and neuropsychiatric diseases remain poorly treated and constitute a major cause of disability worldwide. Several of these pathologies are localized to a specific area of the brain, and their treatment remains inadequate: systemically administered drugs reach the affected areas only in limited concentrations and without precise spatiotemporal control. While the blood-brain barrier and the structural heterogeneity of the brain severely limit the targeted delivery of drugs, alternative approaches such as intracranial pharmacology offer promising prospects. However, these methods remain passive: drug diffusion is neither dose-dependent nor controllable over time, which limits their clinical efficacy. Meanwhile, nanotechnologies offer stable and versatile vectors capable of efficiently encapsulating and transporting various therapeutic agents, but they do not, on their own, allow for localized and on-demand delivery. Our approach addresses these limitations by developing photoactivatable polymersomes capable of releasing their contents in a localized manner under the influence of light.
My work is based on three main axes: (i) the design of photoactivable and biocompatible polymersomes; (ii) the evaluation of their safety in order to ensure safe and effective use at the level of brain tissue; (iii) the demonstration of an efficient photorelease of bioactive molecules in neuronal circuits.
Our work confirmed that the emulsion-centrifugation process is a suitable method for obtaining a high yield of photoactivable micrometer-sized polymersomes (mean diameter of 8.27 ± 0.14 µm), capable of rapid and localized release of their contents, with a mean release time of 6.39 ± 0.90 s. The biocompatibility and release capacity of these polymersomes were evaluated in vitro on primary murine cortical cultures. Neither illumination at 470 nm (optical fiber Ø 400 µm, NA 0.5, 20 s), nor incubation with polymersomes at increasing concentrations (600 to 9000 polymersomes/well), nor the combination of the two affected cell viability. In vivo tolerance was confirmed by injecting polymersomes into the brains of mice and analyzing glial reactivity by immunolabeling IBA-1 and GFAP proteins 48 hours and 3 weeks post-injection. The polymersomes did not elicit any glial response beyond the effect of the stereotaxic injection itself, demonstrating that the polymersomes and their photoactivation are well tolerated by brain cells and tissues. To demonstrate the efficacy of photorelease in brain tissue and to quantify its ability to modulate neuronal processes, we developed a protocol based on measuring neuronal activity. Electrophysiological recordings were performed on mouse brain sections preserving the synaptic connection between the CA3 and CA1 regions of the hippocampus, a key area involved in memory processes. Thanks to the encapsulation and then photorelease of CNQX (100 µM), a competitive antagonist of AMPA/kainate receptors, we have demonstrated that polymersomes act as on-demand reservoirs, allowing prolonged and localized drug administration around the injection site.
In conclusion, photoactivable polymersomes represent a promising tool for studying brain mechanisms and developing innovative therapeutic strategies. Their potential is currently being evaluated in vivo in a murine model of glioblastoma for the targeted release of CNQX to limit tumor invasion.
Keywords: polymersomes, targeted molecular delivery, photostimulation, brain
Publication
https://doi.org/10.21203/rs.3.rs-9232875/v1
Jury
- Mme BOSCH-BOUJU Clémentine – Maître de conférences, Nutrineuro (Bordeaux) – Directrice de thèse
- Mme NADJAR Agnès – Professeure, IMN (Bordeaux) – Présidente du jury
- Mme MURA Simona – Professeure, Institut Galien Paris-Saclay (Paris) – Rapporteur
- M. VENANCE Laurent – Directeur de recherche, Collège de France (Paris) – Rapporteur
- Mme MUTSCHLER Angela – Maître de conférences, LCPO (Bordeaux) – Examinateur
- M. CAZORLA Maxime – Chargé de recherche, INT (Marseille) – Examinateur
- Membres invités :
– M. LECOMMANDOUX Sébastien – Professeur, LCPO (Bordeaux)
– M. MCCLENAGHAN Nathan – Directeur de recherche, ISM (Bordeaux)