Background The deposition of toxic aggregated amyloid-β (Aβ), resulting from continuous cleavage of amyloid precursor protein (APP) by β-site APP cleaving enzyme 1 (BACE1) and γ-secretase, is a key pathogenic event in Alzheimer's disease (AD). Small interfering RNAs (siRNA) have shown great potential for disease treatment by specifically silencing target genes. However, the poor brain delivery efficiency of siRNAs limits their therapeutic efficacy against AD. Methods We designed a simplified and effective BACE1 siRNA (siBACE1) delivery system, namely, dendritic polyamidoamine modified with the neurotropic virus-derived peptide RVG29 and polyethylene glycol (PPR@siBACE1). Results PPR@siBACE1 crossed the blood–brain barrier efficiently and entered brain parenchyma in large amount, with subsequent neurotropism and potential microglia-targeting ability. Both in vitro and in vivo studies validated the effective brain delivery of siBACE1 and strong BACE1 silencing efficiency. Treatment of AD mice with PPR@siBACE1 inhibited the production of Aβ, potentiated Aβ phagocytosis by microglia, improved the memory deficits and reduced neuroinflammatory response in AD mice. Conclusions This study provides a reliable delivery platform for gene therapies for AD.
Alzheimer’s disease (AD), characterized by β -amyloid (A β ) aggregation and neuroinflammation, remains a formidable clinical challenge. Herein, we present an innovative nose-to-brain delivery platform utilizing lactoferrin (Lf)-functionalized lipid nanoparticles (LNPs) co-encapsulating α -mangostin ( α -M) and β -site APP cleaving enzyme 1 (BACE1) siRNA (siB). This dual-modal therapeutic system synergistically combines the neuroprotective and microglia-reprogramming capabilities of α -M with the transcriptional silencing of BACE1 via siB, thereby simultaneously inhibiting A β production and enhancing its clearance. Fabricated via a microfluidic approach, the LNPs exhibited uniform particle size distribution, great encapsulation efficiency, and robust colloidal stability. Upon intranasal administration, Lf-functionalization enabled superior brain-targeting efficacy through receptor-mediated transcytosis. In vitro studies demonstrated that α -M reversed A β -induced low-density lipoprotein receptor downregulation, promoting microglial phagocytosis and autophagic degradation of A β , while siB effectively suppressed BACE1 expression, abrogating A β synthesis. In vivo investigations in APP/PS1 transgenic mice revealed remarkable cognitive recovery, substantial A β plaque reduction, and alleviation of neuroinflammation and oxidative stress. This intricately designed LNP system, exploiting a non-invasive and efficient nose-to-brain delivery route, provides a biocompatible, synergistic, and transformative therapeutic strategy for the multifaceted management of AD.
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