Researchers in Shanghai have used 3D-printed acoustic holograms fitted to a single ultrasound transducer to open the blood-brain barrier along the edges of stroke damage in mice, helping two experimental repair treatments reach the injured tissue. The study, led by ShanghaiTech University with Shanghai Jiao Tong University and Harbin Institute of Technology, was published in Nature Communications on 25 October.
The work was done only in male mice, and the human side of the study is computer simulation using skull models. There has been no human trial. In the mice, the authors report that a single two-minute treatment cut brain atrophy by about 56% when paired with the therapies.
In brief
- A 3D-printed hologram shaped one transducer’s beam into several focal points matched to the borders of a stroke.
- In male mice, one two-minute session helped vesicles and stem cells reach the damaged area and improved recovery.
- Human use was tested only in skull-based simulations; there has been no human trial.
How the holograms shape the beam
The blood-brain barrier keeps most drugs in the bloodstream out of the brain. Focused ultrasound can open it briefly at one spot, but strokes leave damage of irregular shapes and sizes. The team’s platform, which it calls hologram-assisted multitarget BBB opening (HaMBO), places a 3D-printed plate on a flat transducer so that the beam splits into several foci at once.
According to the paper’s supplementary material, the transducer had a 30 mm aperture and worked at 1.5 MHz, focusing on a plane 20 mm from its surface. The team designed holograms with three, four and five foci for mice, using mouse skull models taken from CT scans, and compared simulated fields with hydrophone measurements. It tested pressures from 0.25 to 1 MPa.
The two treatments were extracellular vesicles (EVs), tiny packets released by cells, and mesenchymal stromal cells (MSCs), a type of stem cell, here taken from rat bone marrow. The authors describe HaMBO as low-cost and say it builds on their earlier hologram work in Communications Engineering, published in 2025.
What the mouse results showed
The mice were adult males aged eight to ten weeks, given a temporary blockage of a brain artery to cause a stroke. The stroke groups monitored during surgery held 12 to 15 mice each, and the authors say animals were randomly allocated and that the researchers who assessed results were blinded.
According to the abstract, a single two-minute HaMBO session “safely enhanced the peri-infarct delivery of EVs and MSCs”. It reduced brain atrophy by about 56%, roughly doubled the growth of new blood vessels, increased the multiplication of neural progenitor cells about fourfold and improved long-term behavioural recovery. The supplementary data show that the ultrasound on its own, without either therapy, had “neutral efficacy” on these measures.
The team also ran spatial transcriptomics, which maps gene activity across brain tissue, and linked the vesicle therapy to fewer macrophages, a type of immune cell, and stronger signals for blood vessel and nerve growth. Following peer review, the authors say this analysis used one brain section per group and should be read as “exploratory and associative”.
Why the human work is still on screen
The human-scale work is simulation only. The team modelled human skulls using stroke scans from the public ISLES22 dataset and designed holograms with up to six foci in triangle, square, arc, irregular and double-triangle patterns. It ran the human simulations at 500 kHz with a 200 mm transducer. The abstract says these “further demonstrated HaMBO’s clinical adaptability across diverse stroke scenarios”.
The treatment was given seven days after the stroke. One reviewer noted that the clinical window for stroke treatment is “typically within 3–6 hours after stroke onset”. The authors replied that the study aims at recovery in the subacute-to-chronic stage, not acute treatment, because many patients cannot have clot-removing therapy or still have deficits afterwards.
Only male mice were used, to reduce variability from sex differences in stroke and in ultrasound opening of the barrier. The reporting summary states that “all findings are restricted to male mice”. The authors conclude that HaMBO “provides a safe, low-cost, and customizable platform for noninvasive multitarget delivery in ischemic stroke and other neurological disorders”.
Why the timing and the mice limit the result
This is a proof-of-concept study, and its limits are set out in its own files. Every result comes from young male mice, so nothing yet shows how female animals, older animals or people would respond. The skull simulations show that the beam can, in principle, be shaped for a human head; they say nothing about safety or benefit in patients. The single-section gene analysis is a pointer, not a mechanism. And because treatment came a week after the stroke, the work speaks to recovery rather than emergency care.
Why one printed plate matters more than the numbers
The more durable idea may be the hardware. Shaping a single transducer’s beam with a printed plate, matched to one injury, is a simple set-up, and it fits the irregular damage strokes leave behind. If later work bears that out, the hologram could carry other drugs to other targets, as the authors suggest. Like the Bristol brain organoid work TSN reported and the Sabi brain-signal cap, it is an early step, and the distance to the clinic is long. The KRAS pancreatic cancer vaccine shows how far promising early signals still have to travel.
TSN collects medical and scientific advances on its Tech for Good hub. For now, HaMBO’s precision has been shown in male mice and on simulated skulls, which is where its next tests have to begin.
Sources
- Pan, J.-J., Li, C., Yao, X. et al., “Holographic focused ultrasound enables multitarget EV and MSC delivery for neurovascular repair after ischemic stroke”, Nature Communications, 25 October 2026, doi 10.1038/s41467-026-78847-5: nature.com
- Supplementary Information for the paper: springernature.com
- Reporting Summary for the paper: springernature.com
- Transparent Peer Review file for the paper: springernature.com
- Yao, X. et al., “Acoustic hologram-enabled simultaneous multi-target blood-brain barrier opening (AH-SiMBO)”, Communications Engineering, 2 June 2025: doi.org
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