OBJECTIVE:Preclinical studies in mouse models of Alzheimer's disease present low-intensity ultrasound in a scanning mode (SUS) as a promising neuromodulatory modality. However, given the significant differences in brain scale and complexity between mice and humans, we employed sheep as a large animal model to test a novel investigational device and assess safety as a necessary step before deploying SUS in clinical trials. METHODS:Informed by functional assessments in mice, we used image-guided neuro-navigation to deliver a peak negative pressure of 2.6 MPa to four sheep using a scanning approach. Three sheep (#N1-3) underwent a non-recovery procedure followed by histological assessment, and one (#R1) received five repeated treatments spaced out 2-4 weeks over 12 weeks to assess long-term safety via magnetic resonance imaging (MRI) and behavioral observations. RESULTS:In total, 631 sonications were performed, treating up to 50 individual spots per sheep. Evans blue extravasation, and hematoxylin and eosin and vanadium acid fuchsin-toluidine blue staining revealed no evidence of tissue damage or unintended blood-brain barrier (BBB) opening (given no microbubbles were used). Throughout the repeat treatments of sheep #R1, post-operative behavioral observations confirmed normal movement and no signs of pain or distress. MRI revealed no SUS-induced anatomical abnormalities, evidence of BBB opening, microhemorrhages and oedema, in agreement with the histological observations. Mild heating was observed at the inner skull surface following sonication, but no damage to skull or scalp tissue was detected. CONCLUSION:Collectively, the acute and long-term safety assessment of the brain after SUS advocates translation to human studies.

Drug delivery to the brain presents a major hurdle in developing treatments for neurological disorders. A noninvasive strategy addressing this is transcranial focused ultrasound with microbubbles (FUS+MB) that transiently opens the blood-brain barrier (BBB). Because FUS+MB operates within a narrow therapeutic window, the acoustic pressure needs to be adjusted to factor in a highly variable skull attenuation which is difficult to determine in situ. Here, we used in-house and ClearFit® cranial implants made of PMMA as sonolucent, acoustically homogenous material. k-Wave simulations and in vitro attenuation measurements guided us in establishing optimal implant dimensions. Three sheep procedures were performed using the two implants with peak negative pressures (PNPs) ranging from 278 to 601 kPa, while monitoring broadband and harmonic emissions, and systemically injecting a model drug to visualize BBB opening. BBB opening occurred between 395 and 601 kPa, with the PNP correlating with broadband and harmonic emissions. Our study indicates the utility of sonolucent implants for achieving targeted FUS+MB-mediated BBB opening in the large animal model sheep as revealed with the model drug Evans blue. We foresee that cranioplasties will facilitate FUS+MB-based drug delivery especially for diseases such as glioblastomas which require both craniotomy and radiological treatment monitoring.

Clearing amyloid-β pathology in Alzheimer's disease (AD) has been considered a prerequisite for restoring cognitive functions. Intriguingly, by application of a modality of scanning ultrasound (SUS) to mice that does not remove amyloid-β, we previously achieved significant cognitive improvements. This prompted us to explore SUS as a non-invasive brain stimulation strategy in an open-label safety trial in AD. We conducted a human pilot study in 12 participants with AD with the primary objective of determining feasibility, safety and tolerability. Exploratory secondary end-points were cognitive and behavioural measures, resting-state EEG and functional MRI. A portable device termed UltraTheraPilot was built under medical device standard guidelines, integrating a Brainsight image-guided neuronavigation system. A single-element 286-kHz transducer was programmed to deliver non-derated ultrasound doses of 2.6, 1.95 or 1.3 MPa. With four treatment sessions spaced fortnightly, four participants received 30 sonications per session (precuneus, ∼30 cm3 brain tissue) and the remaining 8 received 100 sonications per session (bilateral precuneus and temporo-parietal association cortex, ∼100 cm3). Safety monitoring, EEG, MRI, cognitive and neuropsychiatric evaluations were performed. The treatment was fast, safe and well-tolerated at the 1.95 MPa dose. MRI showed no changes, whereas changes were observed in aperiodic EEG content. Cognitive performance did not change but statistically significant improvements in behavioural and psychological symptoms were found using the Neuropsychiatric Inventory test. In conclusion, this SUS safety trial met its primary and secondary end-points in biomarker-confirmed mild-to-moderate AD. It informs our future work in an upcoming efficacy trial in an AD population.

A prevalent view in treating age-dependent disorders including Alzheimer’s disease (AD) is that the underlying amyloid plaque pathology must be targeted for cognitive improvements. In contrast, we report here that repeated scanning ultrasound (SUS) treatment at 1 MHz frequency can ameliorate memory deficits in the APP23 mouse model of AD without reducing amyloid-β (Aβ) burden. Different from previous studies that had shown Aβ clearance as a consequence of blood-brain barrier (BBB) opening, here, the BBB was not opened as no microbubbles were used. Quantitative SWATH proteomics and functional magnetic resonance imaging revealed that ultrasound induced long-lasting functional changes that correlate with the improvement in memory. Intriguingly, the treatment was more effective at a higher frequency (1 MHz) than at a frequency within the range currently explored in clinical trials in AD patients (286 kHz). Together, our data suggest frequency-dependent bio-effects of ultrasound and a dissociation of cognitive improvement and Aβ clearance, with important implications for the design of trials for AD therapies.

Alzheimer’s disease is characterized by progressive impairment of neuronal functions culminating in neuronal loss and dementia. A universal feature of dementia is protein aggregation, a process by which a monomer forms intermediate oligomeric assembly states and filaments that develop into end-stage hallmark lesions. In Alzheimer’s disease, this is exemplified by extracellular amyloid-β (Aβ) plaques which have been placed upstream of tau, found in intracellular neurofibrillary tangles and dystrophic neurites. This implies causality that can be modeled as a linear activation cascade. When Aβ load is reduced, for example, in response to an anti-Aβ immunotherapy, cognitive functions improve in plaque-forming mice. They also deteriorate less in clinical trial cohorts although real-world clinical benefits remain to be demonstrated. Given the existence of aged humans with unimpaired cognition despite a high plaque load, the central role of Aβ has been challenged. A counter argument has been that clinical symptoms would eventually develop if these aged individuals were to live long enough. Alternatively, intrinsic mechanisms that protect the brain in the presence of pathology may exist. In fact, Aβ toxicity can be abolished by either reducing or manipulating tau (through which Aβ signals), at least in preclinical models. In addition to manipulating steps in this linear pathocascade model, mechanisms of restoring brain reserve can also counteract Aβ toxicity. Low-intensity ultrasound is a neuromodulatory modality that can improve cognitive functions in Aβ-depositing mice without the need for removing Aβ. Together, this highlights a dissociation of Aβ and cognition, with important implications for therapeutic interventions.

Rationale Intracranial scanning ultrasound combined with intravenously injected microbubbles (SUS +MB ) has been shown to transiently open the blood-brain barrier and reduce amyloid-β (Aβ) pathology in the APP23 mouse model of Alzheimer’s disease (AD). This has been accomplished, at least in part, through the activation of microglial cells; however, their response to the SUS treatment is only incompletely understood. Methods Wild-type (WT) and APP23 mice were subjected to SUS +MB , using non-SUS +MB -treated mice as sham controls. After 48 hours, the APP23 mice were injected with methoxy-XO4 to label Aβ aggregates, followed by microglial isolation into XO4 + and XO4 - populations using flow cytometry. Both XO4 + and XO4 - cells were subjected to RNA sequencing and their transcriptome was analyzed through a bioinformatics pipeline. Results The transcriptomic analysis of the microglial cells revealed a clear segregation depending on genotype (AD model versus WT mice), as well as treatment (SUS +MB versus sham) and Aβ internalization (XO4 + versus XO4 - microglia). Differential gene expression analysis detected 278 genes that were significantly changed by SUS +MB in the XO4 + cells (248 up/30 down) and 242 in XO - cells (225 up/17 down). Not surprisingly given previous findings of increased phagocytosis of plaques following SUS +MB , the pathway analysis highlighted that the treatment induced an enrichment in genes related to the phagosome pathway in XO4 + microglia; however, when comparing SUS +MB to sham, the analysis revealed an enrichment in genes involved in the cell cycle in both the XO4 + and XO4 - microglial population. Conclusion Our data provide a comprehensive analysis of microglia in an AD mouse model subjected to ultrasound treatment as a function of Aβ internalization, one of the defining hallmarks of AD. Several differentially expressed genes are highlighted, pointing to an ultrasound-induced activation of cell cycle mechanisms in microglial cells isolated from APP23 mice treated with SUS +MB . Graphical abstract

Rationale: The blood-brain barrier (BBB) is a major impediment to therapeutic intracranial drug delivery for the treatment of neurodegenerative diseases, including Alzheimer's disease (AD). Focused ultrasound applied together with microbubbles (FUS+MB) is a novel technique to transiently open the BBB and increase drug delivery. Evidence suggests that FUS+MB is safe, however, the effects of FUS+MB on human BBB cells, especially in the context of AD, remain sparsely investigated. In addition, there currently are no cell platforms to test for FUS+MB-mediated drug delivery. Methods: Here we generated BBB cells (induced brain endothelial-like cells (iBECs) and astrocytes (iAstrocytes)) from apolipoprotein E gene allele E4 (APOE4, high sporadic AD risk) and allele E3 (APOE3, lower AD risk) carrying patient-derived induced pluripotent stem cells (iPSCs). We established mono- and co-culture models of human sporadic AD and control BBB cells to investigate the effects of FUS+MB on BBB cell phenotype and to screen for the delivery of two potentially therapeutic AD antibodies, an Aducanumab-analogue (AduhelmTM; anti-amyloid-β) and a novel anti-Tau antibody, RNF5. We then developed a novel hydrogel-based 2.5D BBB model as a step towards a more physiologically relevant FUS+MB drug delivery platform. Results: When compared to untreated cells, the delivery of Aducanumab-analogue and RNF5 was significantly increased (up to 1.73 fold), across the Transwell-based BBB models following FUS+MB treatment. Our results also demonstrated the safety of FUS+MB indicated by minimal changes in iBEC transcriptome as well as little or no changes in iBEC or iAstrocyte viability and inflammatory responses within the first 24 h post FUS+MB. Furthermore, we demonstrated successful iBEC barrier formation in our novel 2.5D hydrogel-based BBB model with significantly increased delivery (1.4 fold) of Aducanumab-analogue following FUS+MB. Conclusion: Our results demonstrate a robust and reproducible approach to utilize patient cells for FUS+MB-mediated drug delivery screening in vitro. With such a cell platform for FUS+MB research previously not reported, it has the potential to identify novel FUS+MB-deliverable drugs as well as screen for cell- and patient-specific effects of FUS+MB, accelerating the use of FUS+MB as a therapeutic modality in AD.

Rationale: The blood-brain barrier (BBB) while functioning as a gatekeeper of the brain, impedes cerebral drug delivery. An emerging technology to overcome this limitation is focused ultrasound (FUS). When FUS interacts with intravenously injected microbubbles (FUS+MB), the BBB opens, transiently allowing the access of therapeutic agents into the brain. However, the ultrasound parameters need to be tightly tuned: when the acoustic pressure is too low there is no opening, and when it is too high, tissue damage can occur. We therefore asked whether barrier permeability can be increased by combining FUS+MB with a second modality such that in a clinical setting lower acoustic pressures could be used. Methods: Given that FUS+MB achieves BBB opening in part by disruption of tight junction (TJ) proteins such as claudin-5 of brain endothelial cells, we generated a stable MDCK (Madin-Darby Canine Kidney) II cell line (eGFP-hCldn5-MDCK II) that expresses fluorescently tagged human claudin-5. Two claudin-5 binders, the peptide mC5C2 and cCPEm (truncated form of an enterotoxin), reported previously to weaken the barrier, were synthesized and assessed for their abilities to enhance the permeability of cellular monolayers. We then performed a comparative analysis of single and combination treatments, measuring transendothelial electrical resistance (TEER) and cargo leakage, combined with confocal image analysis. Results: We successfully generated a novel cell line that formed functional monolayers as validated by an increased TEER reading and a low (< 0.2%) permeability to sodium fluorescein (376 Da). We found that the binders exerted a time-and concentration-dependent effect on barrier opening when incubated over an extended period, whereas FUS+MB caused a rapid opening followed by recovery after 12 hours within the tested pressure range. Importantly, preincubation with cCPEm prior to FUS+MB treatment resulted in greater barrier opening compared to either FUS+MB or cCPEm alone as measured by reduced TEER values and an increased permeability to fluorescently labelled 40 kDa dextran (FD40). Conclusion: The data suggest that pre incubation with clinically suitable binders to TJ proteins may be a general strategy to facilitate safer and more effective ultrasound-mediated BBB opening in cellular and animal systems and potentially also for the treatment of human diseases of the brain.

Background Aducanumab is an anti-amyloid-β (Aβ) antibody that achieved reduced amyloid pathology in Alzheimer’s disease (AD) trials; however, it is controversial whether it also improved cognition, which has been suggested would require a sufficiently high cumulative dose of the antibody in the brain. Therapeutic ultrasound, in contrast, has only begun to be investigated in human AD clinical trials. We have previously shown that scanning ultrasound in combination with intravenously injected microbubbles (SUS), which temporarily and safely opens the blood-brain barrier (BBB), removes amyloid and restores cognition in APP23 mice. However, there has been no direct testing of how the effects of SUS compare to immunotherapy or whether a combination therapy is more effective. Methods In a study comprising four treatment arms, we tested the efficacy of an Aducanumab analog, Adu, both in comparison to SUS, and as a combination therapy, in APP23 mice (aged 13–22 months), using sham as a control. The active place avoidance (APA) test was used to test spatial memory, and histology and ELISA were used to measure amyloid. Brain antibody levels were also determined. Results We found that both Adu and SUS reduced the total plaque area in the hippocampus with no additive effect observed with the combination treatment (SUS + Adu). Whereas in the cortex where there was a trend towards reducing the total plaque area from either Adu or SUS, only the combination treatment yielded a statistically significant decrease in total plaque area compared to sham. Only the SUS and SUS + Adu groups included animals that had their plaque load reduced to below 1% from above 10%. There was a robust improvement in spatial memory for the SUS + Adu group only, and in this group the level of Adu, when measured 3 days post-treatment, was 5-fold higher compared to those mice that received Adu on its own. Together, these findings suggest that SUS should be considered as a treatment option for AD. Alternatively, a combination trial using Aducanumab together with ultrasound to increase brain levels of the antibody may be warranted.

Only a small fraction of therapeutic antibodies targeting brain diseases are taken up by the brain. Focused ultrasound offers a possibility to increase uptake of antibodies and engagement through transient opening of the blood-brain barrier (BBB). In our laboratory, we are developing therapeutic approaches for neurodegenerative diseases in which an antibody in various formats is delivered across the BBB using microbubbles, concomitant with focused ultrasound application through the skull targeting multiple spots, an approach we refer to as scanning ultrasound (SUS). The mechanical effects of microbubbles and ultrasound on blood vessels increases paracellular transport across the BBB by transiently separating tight junctions and enhances vesicle- mediated transcytosis, allowing antibodies and therapeutic agents to effectively cross. Moreover, ultrasound also facilitates the uptake of antibodies from the interstitial brain into brain cells such as neurons where the antibody distributes throughout the cell body and even into neuritic processes. In our studies, fluorescently labeled antibodies are prepared, mixed with in-house prepared lipid-based microbubbles and injected into mice immediately before SUS is applied to the brain. The increased antibody concentration in the brain is then quantified. To account for alterations in normal brain homeostasis, microglial phagocytosis can be used as a cellular marker. The generated data suggest that ultrasound delivery of antibodies is an attractive approach to treat neurodegenerative diseases.

The microtubule-associated protein tau is an attractive therapeutic target for the treatment of Alzheimer’s disease and related tauopathies as its aggregation strongly correlates with disease progression and is considered a key mediator of neuronal toxicity. Delivery of most therapeutics to the brain is, however, inefficient, due to their limited ability to cross the blood-brain barrier (BBB). Therapeutic ultrasound is an emerging non-invasive technology which transiently opens the BBB in a focused manner to allow peripherally delivered molecules to effectively enter the brain. In order to open a large area of the BBB, we developed a scanning ultrasound (SUS) approach by which ultrasound is applied in a sequential pattern across the whole brain. We have previously shown that delivery of an anti-tau antibody in a single-chain variable fragment (scFv) format to the brain is increased with SUS allowing for an enhanced therapeutic effect. Here we compared the delivery of an anti-tau antibody, RN2N, in an scFv, fragment antigen-binding (Fab) and full-sized immunoglobulin G (IgG) format, with and without sonication, into the brain of pR5 tau transgenic mice, a model of tauopathy. Our results revealed that the full-sized IgG reaches a higher concentration in the brain compared with the smaller formats by bypassing renal excretion. No differences in either the ultrasound-mediated uptake or distribution in the brain from the sonication site was observed across the different antibody formats, suggesting that ultrasound can be used to successfully increase the delivery of therapeutic molecules of various sizes into the brain for the treatment of neurological diseases.

A major challenge in treating brain diseases is presented by the blood-brain barrier (BBB) that constitutes an efficient barrier not only for toxins but also a wide range of therapeutic agents. In overcoming this impediment, ultrasound in combination with intravenously injected microbubbles has emerged as a powerful technology that allows for the selective brain uptake of blood-borne factors and therapeutic agents by transient opening of the blood-brain barrier. We have previously shown that ultrasound in combination with microbubbles, but in the absence of a therapeutic agent, can effectively clear protein aggregates such as the hallmark lesions of Alzheimer's disease, amyloid-β (Aβ) plaques and Tau-containing neurofibrillary tangles. We have also demonstrated that the associated memory and motor impairments can be ameliorated or even restored. These studies included a negative sham control that received microbubbles in the absence of ultrasound. However, considering that ultrasound on its own is a pressure wave which has bioeffects, the possibility remained that ultrasound, without microbubbles, would also clear amyloid. We addressed this by performing repeated ultrasound only treatments of one brain hemisphere of Aβ-depositing APP23 mice, using the contralateral hemisphere as the unsonicated control. This was followed by an extensive histological analysis of fibrillar and non-fibrillar amyloid. We found that ultrasound on its own was not sufficient to clear amyloid. This implies that although ultrasound on its own has neuromodulatory effects, exogenously supplied microbubbles are required for the clearance of Aβ deposits.

Intracellular deposits of pathological tau are the hallmark of a broad spectrum of neurodegenerative disorders collectively known as tauopathies, with Alzheimer's disease, a secondary tauopathy, being further characterized by extracellular amyloid plaques. A major obstacle in developing effective treatments for tauopathies is the presence of the blood-brain barrier, which restricts the access of therapeutic agents to the brain. An emerging technology to overcome this limitation is the application of low-intensity ultrasound which, together with intravenously injected microbubbles, transiently opens the blood-brain barrier, thereby facilitating the delivery of therapeutic agents into the brain. Interestingly, even in the absence of therapeutic agents, ultrasound has previously been shown to reduce amyloid plaques and improve cognitive functions in amyloid-depositing mice through microglial clearance. Ultrasound has also been shown to facilitate the delivery of antibody fragments against pathological tau in P301L tau transgenic mice; however, the effect of ultrasound alone has not been thoroughly investigated in a tauopathy mouse model. Methods: Here, we performed repeated scanning ultrasound treatments over a period of 15 weeks in K369I tau transgenic mice with an early-onset tau-related motor and memory phenotype. We used immunohistochemical and biochemical methods to analyze the effect of ultrasound on the mice and determine the underlying mechanism of action, together with an analysis of their motor and memory functions following repeated ultrasound treatments. Results: Repeated ultrasound treatments significantly reduced tau pathology in the absence of histological damage. Associated impaired motor functions showed improvement towards the end of the treatment regime, with memory functions showing a trend towards improvement. In assessing potential clearance mechanisms, we ruled out a role for ubiquitination of tau, a prerequisite for proteasomal clearance. However, the treatment regime induced the autophagy pathway in neurons as reflected by an increase in the autophagosome membrane marker LC3II and a reduction in the autophagic flux marker p62, along with a decrease of mTOR activity and an increase in beclin 1 levels. Moreover, there was a significant increase in the interaction of tau and p62 in the ultrasound-treated mice, suggesting removal of tau by autophagosomes. Conclusions: Our findings indicate that a neuronal protein aggregate clearance mechanism induced by ultrasound-mediated blood-brain barrier opening operates for tau, further supporting the potential of low-intensity ultrasound to treat neurodegenerative disorders.

Alzheimer's disease is characterized by amyloid-β and tau deposition. A challenge in targeting these molecules is presented by the blood-brain barrier (BBB), that limits brain uptake of therapeutic agents. The BBB can be transiently opened by intravenously injecting microbubbles followed by delivering ultrasound through the skull into the brain. We have shown previously by applying scanning ultrasound (SUS) to APP23 mice, that amyloid-β was removed and memory functions restored without using any therapeutic agent. As an underlying mechanism we identified the activation of microglial cells that are activated by blood-borne factors that enter the brain during BBB opening (Leinenga and Götz, Science Transl Med 2015). We also showed that SUS facilitates the uptake of an anti-tau therapeutic antibody fragment, leading to improved therapeutic outcomes (Nisbet et al., Brain 2017). A challenge is to develop the technology for the application in humans, due to a highly attenuating human skull. The objective of the current work was to determine the suitability of SUS in aged APP23 mice, to improve the SUS protocol to treat tau pathology, and (iii) to validate different antibody formats in SUS-mediated brain uptake. We applied SUS to aged (2 year-old) APP23 mice, optimized the SUS treatment regime in tau transgenic K3 mice, and tested different anti-tau antibody formats for SUS-mediated brain uptake in tau transgenic pR5 mice using a Bruker In Vivo MS FX Pro optical imaging system with x-ray and a 630 nm excitation and a 700 nm emission filter. We found that aged APP23 mice that had been exposed to four SUS sessions spaced out over eight weeks and analyzed 4 weeks later did not show any evidence of increased cerebral amyloid angiopathy or microbleeds. Moreover, amyloid was significantly reduced and plaque-associated microglia were more numerous in SUS-treated mice. We identified that 14 weekly SUS treatments of K3 mice significantly reduced tau pathology and improved memory and motor functions. We further identified the best of four antibody formats in SUS-mediated uptake across the BBB and into pR5 neurons. Our study suggests therapeutic ultrasound as a viable modality to treat proteinopathies.

Ultrasound is increasingly being recognized as a neuromodulatory and therapeutic tool, inducing a broad range of bio-effects in the tissue of experimental animals and humans. To achieve these effects in a predictable manner in the human brain, the thick cancellous skull presents a problem, causing attenuation. In order to overcome this challenge, as a first step, the acoustic properties of a set of simple bone-modeling resin samples that displayed an increasing geometrical complexity (increasing step sizes) were analyzed. Using two Non-Destructive Testing (NDT) transducers, we found that Wiener deconvolution predicted the Ultrasound Acoustic Response (UAR) and attenuation caused by the samples. However, whereas the UAR of samples with step sizes larger than the wavelength could be accurately estimated, the prediction was not accurate when the sample had a smaller step size. Furthermore, a Finite Element Analysis (FEA) performed in ANSYS determined that the scattering and refraction of sound waves was significantly higher in complex samples with smaller step sizes compared to simple samples with a larger step size. Together, this reveals an interaction of frequency and geometrical complexity in predicting the UAR and attenuation. These findings could in future be applied to poro-visco-elastic materials that better model the human skull.

Rationale: Treating diseases of the brain such as Alzheimer's disease (AD) is challenging as the blood-brain barrier (BBB) effectively restricts access of a large number of potentially useful drugs. A potential solution to this problem is presented by therapeutic ultrasound, a novel treatment modality that can achieve transient BBB opening in species including rodents, facilitated by biologically inert microbubbles that are routinely used in a clinical setting for contrast enhancement. However, in translating rodent studies to the human brain, the presence of a thick cancellous skull that both absorbs and distorts ultrasound presents a challenge. A larger animal model that is more similar to humans is therefore required in order to establish a suitable protocol and to test devices. Here we investigated whether sheep provide such a model. Methods: In a stepwise manner, we used a total of 12 sheep to establish a sonication protocol using a spherically focused transducer. This was assisted by ex vivo simulations based on CT scans to establish suitable sonication parameters. BBB opening was assessed by Evans blue staining and a range of histological tests. Results: Here we demonstrate noninvasive microbubble-mediated BBB opening through the intact sheep skull. Our non-recovery protocol allowed for BBB opening at the base of the brain, and in areas relevant for AD, including the cortex and hippocampus. Linear time-shift invariant analysis and finite element analysis simulations were used to optimize the position of the transducer and to predict the acoustic pressure and location of the focus. Conclusion: Our study establishes sheep as a novel animal model for ultrasound-mediated BBB opening and highlights opportunities and challenges in using this model. Moreover, as sheep develop an AD-like pathology with aging, they represent a large animal model that could potentially complement the use of non-human primates.

Deposition of amyloid-β (Aβ) peptide leads to amyloid plaques that together with tau deposits characterize the brains of patients with Alzheimer's disease (AD). In modeling this pathology, transgenic animals such as the APP23 strain, that expresses a mutant form of the amyloid precursor protein found in familial cases of AD, have been instrumental. In previous studies, we have shown that repeated treatments with ultrasound in a scanning mode (termed scanning ultrasound or SUS) were effective in removing Aβ and restoring memory functions, without the need for a therapeutic agent such as an Aβ antibody. Considering that age is the most important risk factor for AD, we extended this study in which the mice were only 12 months old at the time of treatment by assessing a cohort of 2 year-old mice. Interestingly, at this age, APP23 mice are characterized by cerebral amyloid angiopathy (CAA) and the presence of occasional microbleeds. We found that SUS in aged mice that have been exposed to four SUS sessions that were spread out over 8 weeks and analyzed 4 weeks later did not show evidence of increased CAA or microbleeds. Furthermore, amyloid was reduced as assessed by methoxy-XO4 fluorescence. In addition, plaque-associated microglia were more numerous in SUS treated mice. Together this adds to the notion that SUS may be a treatment modality for human neurodegenerative diseases.

Medical Journal of AustraliaVolume 206, Issue 11 p. 470-471 Perspective Ultrasound as a treatment modality for neurological diseases Gerhard Leinenga, Gerhard Leinenga Queensland Brain Institute, University of Queensland, Brisbane, QLDSearch for more papers by this authorRebecca M Nisbet, Rebecca M Nisbet Queensland Brain Institute, University of Queensland, Brisbane, QLDSearch for more papers by this authorJürgen Götz, Corresponding Author Jürgen Götz j.goetz@uq.edu.au Queensland Brain Institute, University of Queensland, Brisbane, QLDCorrespondence: j.goetz@uq.edu.auSearch for more papers by this author Gerhard Leinenga, Gerhard Leinenga Queensland Brain Institute, University of Queensland, Brisbane, QLDSearch for more papers by this authorRebecca M Nisbet, Rebecca M Nisbet Queensland Brain Institute, University of Queensland, Brisbane, QLDSearch for more papers by this authorJürgen Götz, Corresponding Author Jürgen Götz j.goetz@uq.edu.au Queensland Brain Institute, University of Queensland, Brisbane, QLDCorrespondence: j.goetz@uq.edu.auSearch for more papers by this author First published: 19 June 2017 https://doi.org/10.5694/mja16.01013Citations: 1Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume206, Issue11June 2017Pages 470-471 RelatedInformation