Treatment of neurodegenerative diseases has become one of the most challenging topics of the last decades due to their prevalence and increasing societal cost. The crucial point of the non-invasive therapeutic strategy for neurological disorder treatment relies on the drugs’ passage through the blood-brain barrier (BBB). Indeed, this biological barrier is involved in cerebral vascular homeostasis by its tight junctions, for example. One way to overcome this limit and deliver neuroprotective substances in the brain relies on nanotechnology-based approaches. Poly(lactic-co-glycolic acid) nanoparticles (PLGA NPs) are biocompatible, non-toxic, and provide many benefits, including improved drug solubility, protection against enzymatic digestion, increased targeting efficiency, and enhanced cellular internalization. This review will present an overview of the latest findings and advances in the PLGA NP-based approach for neuroprotective drug delivery in the case of neurodegenerative disease treatment (i.e., Alzheimer’s, Parkinson’s, Huntington’s diseases, Amyotrophic Lateral, and Multiple Sclerosis).

Parkinson's disease (PD) is an age‐related neurodegenerative disorder characterized by the loss of dopaminergic neurons in the substantia nigra, associated with the accumulation of misfolded α‐synuclein and lysosomal impairment, two events deemed interconnected. Protein aggregation is linked to defects in degradation systems such as the autophagy‐lysosomal pathway, while lysosomal dysfunction is partly related to compromised acidification. We have recently proven that acidic nanoparticles (aNPs) can re‐acidify lysosomes and ameliorate neurotoxin‐mediated dopaminergic neurodegeneration in mice. However, no lysosome‐targeted approach has yet been tested in synucleinopathy models in vivo. Here, we show that aNPs increase α‐synuclein degradation through enhancing lysosomal activity in vitro. We further demonstrate in vivo that aNPs protect nigral dopaminergic neurons from cell death, ameliorate α‐synuclein pathology, and restore lysosomal function in mice injected with PD patient‐derived Lewy body extracts carrying toxic α‐synuclein aggregates. Our results support lysosomal re‐acidification as a disease‐modifying strategy for the treatment of PD and other age‐related proteinopathies.

The Autophagy Lysosomal Pathway is one of the most important mechanisms for removing dysfunctional cellular components. Increasing evidence suggests that alterations in this pathway play a pathogenic role in Parkinson’s disease, making it a point of particular vulnerability. Numerous studies have proposed nanotechnologies as a promising approach for delivering active substances within the central nervous system to treat and diagnose neurodegenerative diseases. In this context, the aim was to propose the development of a new pharmaceutical technology for the treatment of neurodegenerative diseases. We designed a trehalose-based nanosystem by combining both a small natural autophagy enhancer molecule named trehalose and an amphiphilic nucleolipid conjugate. To improve nucleolipid protection and cellular uptake, these conjugates were formulated by rapid mixing in either solid lipid nanoparticles (Ø = 120.4 ± 1.4 nm) or incorporated into poly(lactic-co-glycolic acid) nanoparticles (Ø = 167.2 ± 2.4 nm). In vitro biological assays demonstrated a safe and an efficient cellular uptake associated with autophagy induction. Overall, these nucleolipid-based formulations represent a promising new pharmaceutical tool to deliver trehalose and restore the autophagy impaired function.

Cette thèse a porté sur le développement de nouveaux vecteurs thérapeutiques pour le traitement de la maladie de Parkinson. La maladie de Parkinson est une maladie neurodégénérative qui se caractérise notamment par la présence d’inclusions protéiques intracytoplasmiques appelées « corps de Lewy ». L'une des causes de la formation de ces « corps de Lewy », principalement composés d’α-synucléine, serait l’atteinte du système autophagie-lysosome, nécessaire à la dégradation des composants cellulaires. Le rétablissement des fonctions de l’autophagie constitue donc une cible thérapeutique intéressante pour lutter contre la maladie de Parkinson. Une approche interdisciplinaire a permis de travailler sur les diverses étapes de la recherche à visée thérapeutique, de la synthèse chimique de substances actives à leur nano-formulation, puis à l’évaluation biologique de ces nanovecteurs. Premièrement, les propriétés biologiques de restauration du pH lysosomal des nanoparticules de poly(acide lactique-co-glycolique) (PLGA) ont été étudiées. Cette première partie a permis de conclure que ces nanoparticules possédaient une activité neuroprotectrice, tout en améliorant la synucléinopathie et un rétablissement de la fonction lysosomale chez un modèle murin de la maladie de Parkinson. Deuxièmement, l’effet thérapeutique d’une substance active reconnue comme neuroprotectrice, le tréhalose, a été évalué in-vitro sur une lignée cellulaire (BE (2)-M17), notamment pour sa capacité d’activation de l’autophagie. Des dérivés nucléolipide-tréhalose (appelés GlycoNucléoLipides ou GNL) ont donc été développés et synthétisés avant leur encapsulation à l’intérieur de nanoparticules de PLGA. Ces GNL ont également montré leur capacité d’auto-assemblage pour former des nanoparticules solides lipidiques (appelées SLN) capables, comme leurs analogues de PLGA, de traverser les membranes cellulaires et d’induire une activation de l’autophagie.