RVG29-functionalized nanocarriers for brain-targeted therapy of neurodegenerative diseases: mechanisms, therapeutic advances, and translational perspectives.

Neurodegenerative diseases (NDs) affect more than 55 million people worldwide, with this number projected to exceed 139 million by 2050 due to population aging. Alzheimer's disease (AD) accounts for 60-70% of dementia cases, while Parkinson's disease (PD) affects over 10 million individuals globally, highlighting the growing clinical and socioeconomic burden of these progressive neurological disorders. Effective treatment of AD, PD, amyotrophic lateral sclerosis (ALS), and related central nervous system disorders remains hindered by the blood-brain barrier (BBB), poor brain accumulation, rapid systemic clearance, and off-target toxicity. RVG29, a 29-amino-acid peptide derived from rabies virus glycoprotein, has emerged as a promising brain-targeting ligand because of its high affinity for nicotinic acetylcholine receptors expressed on neuronal and brain endothelial cells. This review critically examines the mechanisms underlying RVG29-mediated receptor-dependent BBB transcytosis, intracellular trafficking, and neuronal uptake. Furthermore, it comprehensively evaluates RVG29-functionalized lipid nanoparticles, polymeric nanoparticles, exosomes, biomimetic nanocarriers, micelles, inorganic nanostructures, and hybrid systems with respect to their physicochemical characteristics, targeting efficiency, therapeutic efficacy, and safety. Collectively, these nanocarriers demonstrate enhanced BBB penetration, increased drug accumulation in diseased brain regions, and efficient delivery of small molecules, genes, mRNA, and siRNA. By modulating oxidative stress, neuroinflammation, protein aggregation, ferroptosis, and mitochondrial dysfunction, RVG29-engineered nanocarriers provide significant neuroprotection with favorable biocompatibility and minimal immunogenicity. Despite these advances, challenges related to large-scale manufacturing, peptide stability, regulatory approval, and long-term biosafety must be addressed to facilitate their clinical translation as precision neurotherapeutics.