Microneedle-mediated nose-to-brain drug delivery for improved Alzheimer's disease treatment

Conventional transnasal brain-targeted drug delivery strategies are limited by nasal cilia clearance and the nasal mucosal barrier. To address this challenge, we designed dissolving microneedles combined with nanocarriers for enhanced nose-to-brain drug delivery. To facilitate transnasal administration, a toothbrush-like microneedle patch was fabricated with hyaluronic acid-formed microneedles and tannic acid-crosslinked gelatin as the base, which completely dissolved in the nasal mucosa within seconds leaving only the base, thereby releasing the loaded cyclodextrin-based metal-organic frameworks (CD-MOFs) without affecting the nasal cilia and nasal microbial communities. As nanocarriers for high loading of huperzine A, these potassium-structured CD-MOFs, reinforced with stigmasterol and functionalized with lactoferrin, possessed improved physical stability and excellent biocompatibility, enabling efficient brain-targeted drug delivery. This delivery system substantially attenuated H2O2- and scopolamine-induced neurocyte damage. The efficacy of huperzine A on scopolamine- and D-galactose & AlCl3-induced memory deficits in rats was significantly improved, as evidenced by inhibiting acetylcholinesterase activity, alleviating oxidative stress damage in the brain, and improving learning function, meanwhile activating extracellular regulated protein kinases-cyclic AMP responsive element binding protein-brain derived neurotrophic factor pathway. Moreover, postsynaptic density protein PSD-95, which interacts with two important therapeutic targets Tau and β-amyloid in Alzheimer's disease, was upregulated. This fruitful treatment was further shown to significantly ameliorate Tau hyperphosphorylation and decrease β-amyloid by ways including modulating beta-site amyloid precursor protein cleaving enzyme 1 and a disintegrin and metalloproteinase 10. Collectively, such a newly developed strategy breaks the impasse for efficient drug delivery to the brain, and the potential therapeutic role of huperzine A for Alzheimer's disease is further illustrated.