Ultrasound-Mediated Gene Therapy in Alzheimer’s Disease Validated through In Vivo PET Imaging

Efficient, spatially selective delivery of adeno-associated virus (AAV) therapeutics to deep brain structures remains a major challenge to gene therapy for Alzheimer's disease (AD), owing to limited transport across the blood-brain barrier (BBB) and poor penetration to target neurons. Here, we establish an integrated, noninvasive imaging and therapy platform that combines microbubble-enhanced focused ultrasound (MB-FUS) with positron emission tomography/computed tomography (PET/CT) to transiently modulate the BBB, enhance region-specific AAV delivery following systemic dosing, and longitudinally track transduction in vivo. Optimized MB-FUS achieved targeted hippocampal delivery of systemically administered AAV9 in healthy mice, resulting in a 10-fold enhancement of neuronal transduction as compared to non-FUS controls. Importantly, longitudinal PET reporter gene imaging in the 5xFAD AD model demonstrated robust brain AAV transduction that remained stable for at least seven months. Finally, to assess therapeutic impact, we used brain-derived neurotrophic factor (BDNF) as a test cargo. MB-FUS-facilitated delivery elevated BDNF expression in targeted regions and produced short-term improvements in synaptic signaling in 5xFAD mice. Collectively, these results highlight MB-FUS as a next-generation delivery platform to overcome barriers to AAV therapeutic delivery in Alzheimer's disease and position longitudinal PET assessment as a critical, translatable tool for monitoring and optimizing gene therapy.