Ultrasound-Mediated Drug Delivery Across the Blood-Brain Barrier

The blood–brain barrier (BBB) presents a formidable obstacle to the systemic administration of therapeutics for neurological disorders. Recent advances in ultrasound technology have enabled a non-invasive, localised and transient disruption of BBB integrity, facilitating the passage of a wide range of agents from small molecules to antibodies and genetic vectors. By combining focused acoustic waves with intravenously injected microbubbles, safe and reversible opening of endothelial tight junctions can be achieved at millimetre resolution. This approach minimises off-target effects and allows repeated treatments tailored to disease stage. Preclinical studies have demonstrated enhanced drug accumulation in models of Alzheimer’s disease, glioma and neurodegeneration, while pilot clinical trials in patients with Alzheimer’s, amyotrophic lateral sclerosis and brain tumours have confirmed feasibility, tolerability and the absence of serious adverse events. The emerging paradigm of ultrasound-mediated drug delivery promises to transform the treatment of central nervous system disorders by enabling targeted, image-guided administration of therapeutics previously excluded by the BBB.

Research from Nature Portfolio

Recent work in patients with early Alzheimer’s disease has shown that magnetic resonance-guided focused ultrasound (MRgFUS) combined with microbubbles can safely open the BBB in targeted hippocampal regions. The procedure was reversible within hours, produced no serious clinical or radiographic adverse events and maintained stable cognitive scores over three months. In high-grade glioma patients, MRgFUS was used immediately prior to surgical resection to enhance delivery of chemotherapeutic agents. Tissue analyses revealed a 15–50 % increase in drug concentration within sonicated regions, confirming that transient BBB permeabilisation can improve intratumoral drug uptake without compromising safety. More recently, a first-in-human trial in amyotrophic lateral sclerosis subjects demonstrated that MRgFUS targeted to the primary motor cortex produces focal and reversible BBB opening, validated by immediate gadolinium leakage and full closure within 24 hours, laying the groundwork for future therapeutic delivery studies in neurodegenerative disease.

Ultrasound-Mediated Drug Delivery Across the Blood-Brain Barrier publication trend

The graph below shows the total number of articles in ultrasound-mediated drug delivery across the blood-brain barrier across all publications each year (not limited to Nature Index journals).

Technical terms

Blood–brain barrier: A selective endothelial interface that restricts passage of substances from the bloodstream into the central nervous system.

Focused ultrasound: Acoustic waves concentrated at a precise focal point within tissue to induce mechanical or thermal effects.

Microbubble: Gas-filled contrast agent that oscillates under ultrasound, enhancing local mechanical forces on blood vessel walls.

Magnetic resonance-guided focused ultrasound (MRgFUS): Integration of MRI for real-time imaging with focused ultrasound to target and monitor BBB opening.

Sonication: Delivery of ultrasound energy to biological tissue, often in pulses, to produce mechanical disruption or modulation.

References

1. Blood–brain barrier opening in Alzheimer’s disease using MR-guided focused ultrasound. Nature Communications (2018).
2. Blood-Brain Barrier Opening in Primary Brain Tumors with Non-invasive MR-Guided Focused Ultrasound: A Clinical Safety and Feasibility Study. Scientific Reports (2019).
3. First-in-human trial of blood–brain barrier opening in amyotrophic lateral sclerosis using MR-guided focused ultrasound. Nature Communications (2019).
4. Antibodies Targeted to the Brain with Image-Guided Focused Ultrasound Reduces Amyloid-β Plaque Load in the TgCRND8 Mouse Model of Alzheimer's Disease. PLOS ONE (2010).
5. Focused ultrasound-mediated suppression of chemically-induced acute epileptic EEG activity. BMC Neuroscience (2011).