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Background : Focused ultrasound (FUS) in combination with microbubbles has recently shown great promise in facilitating blood-brain barrier (BBB) opening for drug delivery and immunotherapy in Alzheimer's disease (AD). However, it is currently limited to systems integrated within the MRI suites or requiring post-surgical implants, thus restricting its widespread clinical adoption. In this pilot study, we investigate the clinical safety and feasibility of a portable, non-invasive neuronavigation-guided FUS (NgFUS) system with integrated real-time 2-D microbubble cavitation mapping. Methods : A phase 1 clinical study with mild to moderate AD patients (N = 6) underwent a single session of microbubble-mediated NgFUS to induce transient BBB opening (BBBO). Microbubble activity under FUS was monitored with real-time 2-D cavitation maps and dosing to ensure the efficacy and safety of the NgFUS treatment. Post-operative MRI was used for BBB opening and closure confirmation as well as safety assessment. Changes in AD biomarker levels in both blood serum and extracellular vesicles (EVs) were evaluated, while changes in amyloid-beta (Aß) load in the brain were assessed through 18F-florbetapir PET. Results : BBBO was achieved in 5 out of 6 subjects with an average volume of 983 ± 626 mm3 following FUS at the right frontal lobe both in white and gray matter regions. The outpatient treatment was completed within 34.8 ± 10.7 min. Cavitation dose significantly correlated with the BBBO volume (R 2 > 0.9, N = 4), demonstrating the portable NgFUS system's capability of predicting opening volumes. The cavitation maps co-localized closely with the BBBO location, representing the first report of real-time transcranial 2-D cavitation mapping in the human brain. Larger opening volumes correlated with increased levels of AD biomarkers, including Aß42 (R 2 = 0.74), Tau (R 2 = 0.95), and P-Tau181 (R 2 = 0.86), assayed in serum-derived EVs sampled 3 days after FUS (N = 5). From PET scans, subjects showed a lower Aß load increase in the treated frontal lobe region compared to the contralateral region. Reduction in asymmetry standardized uptake value ratios (SUVR) correlated with the cavitation dose (R 2 > 0.9, N = 3). Clinical changes in the mini-mental state examination over 6 months were within the expected range of cognitive decline with no additional changes observed as a result of FUS. Conclusion : We showed the safety and feasibility of this cost-effective and time-efficient portable NgFUS treatment for BBBO in AD patients with the first demonstration of real-time 2-D cavitation mapping. The cavitation dose correlated with BBBO volume, a slowed increase in pathology, and serum detection of AD proteins. Our study highlights the potential for accessible FUS treatment in AD, with or without drug delivery.
Assuntos
Doença de Alzheimer , Barreira Hematoencefálica , Imageamento por Ressonância Magnética , Microbolhas , Humanos , Barreira Hematoencefálica/metabolismo , Barreira Hematoencefálica/diagnóstico por imagem , Doença de Alzheimer/terapia , Doença de Alzheimer/diagnóstico por imagem , Masculino , Idoso , Feminino , Projetos Piloto , Imageamento por Ressonância Magnética/métodos , Peptídeos beta-Amiloides/metabolismo , Pessoa de Meia-Idade , Biomarcadores/metabolismo , Sistemas de Liberação de Medicamentos/métodos , Idoso de 80 Anos ou maisRESUMO
Background: Focused ultrasound (FUS) in combination with microbubbles has recently shown great promise in facilitating blood-brain barrier (BBB) opening for drug delivery and immunotherapy in Alzheimer's disease (AD). However, it is currently limited to systems integrated within the MRI suites or requiring post-surgical implants, thus restricting its widespread clinical adoption. In this pilot study, we investigate the clinical safety and feasibility of a portable, non-invasive neuronavigation-guided FUS (NgFUS) system with integrated real-time 2-D microbubble cavitation mapping. Methods: A phase 1 clinical study with mild to moderate AD patients (N=6) underwent a single session of microbubble-mediated NgFUS to induce transient BBB opening (BBBO). Microbubble activity under FUS was monitored with real-time 2-D cavitation maps and dosing to ensure the efficacy and safety of the NgFUS treatment. Post-operative MRI was used for BBB opening and closure confirmation as well as safety assessment. Changes in AD biomarker levels in both blood serum and extracellular vesicles (EVs) were evaluated, while changes in amyloid-beta (Aß) load in the brain were assessed through 18F-Florbetapir PET. Results: BBBO was achieved in 5 out of 6 subjects with an average volume of 983±626 mm3 following FUS at the right frontal lobe both in white and gray matter regions. The outpatient treatment was completed within 34.8±10.7 min. Cavitation dose significantly correlated with the BBBO volume (R 2>0.9, N=4), demonstrating the portable NgFUS system's capability of predicting opening volumes. The cavitation maps co-localized closely with the BBBO location, representing the first report of real-time transcranial 2-D cavitation mapping in the human brain. Larger opening volumes correlated with increased levels of AD biomarkers, including Aß42 (R 2=0.74), Tau (R 2=0.95), and P-Tau181 (R 2=0.86), assayed in serum-derived EVs sampled 3 days after FUS (N=5). From PET scans, subjects showed a lower Aß load increase in the treated frontal lobe region compared to the contralateral region. Reduction in asymmetry standardized uptake value ratios (SUVR) correlated with the cavitation dose (R 2>0.9, N=3). Clinical changes in the mini-mental state examination over 6 months were within the expected range of cognitive decline with no additional changes observed as a result of FUS. Conclusion: We showed the safety and feasibility of this cost-effective and time-efficient portable NgFUS treatment for BBBO in AD patients with the first demonstration of real-time 2-D cavitation mapping. The cavitation dose correlated with BBBO volume, a slowed increase in pathology, and serum detection of AD proteins. Our study highlights the potential for accessible FUS treatment in AD, with or without drug delivery.
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The opening of the blood-brain barrier (BBB) by focused ultrasound (FUS) coupled with intravenously injected microbubbles can be leveraged as a form of immunotherapy for the treatment of neurodegenerative disorders. However, how FUS BBB opening affects brain macrophages is not well understood. Here by using single-cell sequencing to characterize the distinct responses of microglia and central nervous system-associated macrophages (CAMs) to FUS-mediated BBB opening in mice, we show that the treatment remodels the immune landscape via the recruitment of CAMs and the proliferation of microglia and via population size increases in disease-associated microglia. Both microglia and CAMs showed early and late increases in population sizes, yet only the proliferation of microglia increased at both timepoints. The population of disease-associated microglia also increased, accompanied by the upregulation of genes associated with gliogenesis and phagocytosis, with the depletion of brain macrophages significantly decreasing the duration of BBB opening.
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The amyloid-ß (Aß) hypothesis implicates Aß protein accumulation in Alzheimer's disease (AD) onset and progression. However, therapies targeting Aß have proven insufficient in achieving disease reversal, prompting a shift to focus on early intervention and alternative therapeutic targets. Focused ultrasound (FUS) paired with systemically-introduced microbubbles (µB) is a non-invasive technique for targeted and transient blood-brain barrier opening (BBBO), which has demonstrated Aß and tau reduction, as well as memory improvement in models of late-stage AD. However, similar to drug treatments for AD, this approach is not sufficient for complete reversal of advanced, symptomatic AD. Here we aim to determine whether early intervention with FUS-BBBO in asymptomatic AD could delay disease onset. Thus, the objective of this study is to measure the protective effects of FUS-BBBO on anxiety, memory and AD-associated protein levels in female and male triple transgenic (3xTg) AD mice treated at an early age and disease state. Here we show that early, repeated intervention with FUS-BBBO decreased anxiety-associated behaviors in the open field test by 463.02 and 37.42% in male and female cohorts, respectively. FUS-BBBO preserved female aptitude for learning in the active place avoidance paradigm, reducing the shock quadrant time by 30.03 and 31.01% in the final long-term and reversal learning trials, respectively. Finally, FUS-BBBO reduced hippocampal accumulation of Aß40, Aß42, and total tau in females by 12.54, 13.05, and 3.57%, respectively, and reduced total tau in males by 18.98%. This demonstration of both cognitive and pathological protection could offer a solution for carriers of AD-associated mutations as a safe, non-invasive technique to delay the onset of the cognitive and pathological effects of AD.
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Background: Focused ultrasound (FUS)-mediated blood-brain barrier (BBB) opening is a noninvasive, safe and reversible technique for targeted drug delivery to the brain. Most preclinical systems developed to perform and monitor BBB opening are comprised of a separate geometrically focused transducer and passive cavitation detector (PCD) or imaging array. This study builds upon previous work from our group developing a single imaging phased array configuration for simultaneous BBB opening and monitoring called theranostic ultrasound (ThUS), leveraging ultra-short pulse lengths (USPLs) and a novel rapid alternating steering angles (RASTA) pulse sequence design for simultaneous bilateral sonications with target-specific USPL. The RASTA sequence was further employed to evaluate the impact of USPL on BBB opening volume, power cavitation imaging (PCI) pixel intensity, BBB closing timeline, drug delivery efficiency, and safety. Methods: A P4-1 phased array transducer driven by a Verasonics Vantage ultrasound system was operated using a custom script to run the RASTA sequence which consisted of interleaved steered, focused transmits and passive imaging. Contrast-enhanced magnetic resonance imaging (MRI) confirmed initial opening volume and closure of the BBB by longitudinal imaging through 72 hours post-BBB opening. For drug delivery experiments, mice were systemically administered a 70 kDa fluorescent dextran or adeno-associated virus serotype 9 (AAV9) for fluorescence microscopy or enzyme-linked immunosorbent assay (ELISA) to evaluate ThUS-mediated molecular therapeutic delivery. Additional brain sections were also H&E-stained to evaluate histological damage, and IBA1- and GFAP-stained to elucidate the effects of ThUS-mediated BBB opening on stimulation of key cell types involved in the neuro-immune response, microglia and astrocytes. Results: The ThUS RASTA sequence induced distinct BBB openings simultaneously in the same mouse where volume, PCI pixel intensity, level of dextran delivery, and AAV reporter transgene expression were correlated with brain hemisphere-specific USPL, consistent with statistically significant differences between 1.5, 5, and 10-cycle USPL groups. BBB closure after ThUS required 2-48 hours depending on USPL. The potential for acute damage and neuro-immune activation increased with USPL, but such observable damage was nearly reversed 96 hours post-ThUS. Conclusion: ThUS is a versatile single-array technique which exhibits the potential for investigating a variety of non-invasive therapeutic delivery applications in the brain.
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Barreira Hematoencefálica , Medicina de Precisão , Camundongos , Animais , Barreira Hematoencefálica/metabolismo , Dextranos/metabolismo , Estudos de Viabilidade , UltrassonografiaRESUMO
Optogenetics has revolutionized the capability of controlling genetically modified neurons in vitro and in vivo and has become an indispensable neuroscience tool. Using light as a probe for selective neuronal activation or inhibition and as a means to read out neural activity has dramatically enhanced our understanding of complex neural circuits. However, a common limitation of optogenetic studies to date is their invasiveness and spatiotemporal range. Direct viral injections into the brain tissue along with implantation of optical fibers and recording electrodes can disrupt the neuronal circuitry and cause significant damage. Conventional approaches are spatially limited around the site of the direct injection and insufficient in examining large networks throughout the brain. Lastly, optogenetics is currently not easily scalable to large animals or humans. Here, we demonstrate that optogenetic excitation can be achieved entirely non-invasively through the intact skull in mice. Using a needle-free combination of focused ultrasound-mediated viral delivery and extracorporeal illumination with red light, we achieved selective neuronal activation at depths up to 4 mm in the murine brain, confirmed through cFos expression and electrophysiology measurements within the treated areas. Ultrasound treatment significantly reduced freezing time during recall in fear conditioning experiments, but remote light exposure had a moderate effect on the freezing behavior of mice treated with viral vectors. The proposed method has the potential to open new avenues of studying, but also stimulating, neuronal networks, in an effort to elucidate normal or dysfunctional brain activity and treat neurological diseases. Finally, the same non-invasive methodology could be combined with gene therapy and applied to other organs, such as the eye and the heart.
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Neurônios , Optogenética , Animais , Encéfalo/fisiologia , Terapia Genética , Humanos , Camundongos , Neurônios/fisiologia , Optogenética/métodos , Estimulação LuminosaRESUMO
Focused ultrasound (FUS) for blood-brain barrier (BBB) opening is a safe, reversible and non-invasive strategy for targeted drug delivery to the brain, however extensive pre-planning strategies are necessary for successful FUS-mediated BBB opening through the structurally complex primate skull. OBJECTIVE: This study aims to demonstrate a pre-planning pipeline consisting of transcranial simulations and in vitro experimentation used to inform synchronous BBB opening and power cavitation imaging (PCI) with a single theranostic ultrasound (TUS) phased array. METHODS: Acoustic wave propagation simulation findings of pressure attenuation and focal shift through clinical-CT and micro-CT-based primate skull models were compared, while the latter were used to determine the impact of beam steering angle on focal shift and pressure attenuation. In vitro experimentation with a channel phantom enabled characterization of skull-induced receive focal shift (RFS), while in vivo BBB opening and PCI using in silico and in vitro pre-planning information was conducted using a custom Verasonics/MATLAB script. RESULTS: Simulations confirmed steering angle dependent transcranial focal shift and pressure attenuation, while in vitro experiments revealed minimal (0.30-1.50 mm) skull-induced RFS. In vivo rodent experiments with overlaid primate skull fragments demonstrated successful TUS-mediated BBB opening and spatially correlated power cavitation images (PCI) with regions of BBB opening on T1-weighted magnetic resonance images (MRI). CONCLUSION: We demonstrated the feasibility for TUS-mediated BBB opening in vivo using in silico and in vitro pre-planning information. SIGNIFICANCE: TUS as an ultrasound-guided modality for BBB opening could serve as a promising alternative to current FUS-mediated BBB opening configurations in the clinic.
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Barreira Hematoencefálica , Medicina de Precisão , Animais , Barreira Hematoencefálica/diagnóstico por imagem , Estudos de Viabilidade , Imageamento por Ressonância Magnética/métodos , UltrassonografiaRESUMO
Background: Increasing evidence points to the critical role of extracellular vesicles (EVs) as molecular parcels that carry a diverse array of bioactive payloads for coordination of complex intracellular signaling. Focused ultrasound (FUS) hyperthermia is a technique for non-invasive, non-ionizing sublethal heating of cells in a near-instantaneous manner; while it has been shown to improve drug delivery and immunological recognition of tumors, its impact on EVs has not been explored to date. The goal of this study was to determine whether FUS impacts the release, proteomic profile, and immune-activating properties of tumor-derived EVs. Methods: Monolayered murine glioma cells were seeded within acoustically transparent cell culture chambers, and FUS hyperthermia was applied to achieve complete coverage of the chamber. Glioma-derived EVs (GEVs) were isolated for characterization by Nanoparticle Tracking Analysis, cryo-electron microscopy and mass spectrometry. An in vitro experimental setup was designed to further dissect the impact of GEVs on innate inflammation; immortalized murine dendritic cells (DCs) were pulsed with GEVs (either naïve or FUS hyperthermia-exposed) and assayed for production of IL-12p70, an important regulator of DC maturation and T helper cell polarization toward the interferon-γ-producing type 1 phenotype. Results: We confirmed that FUS hyperthermia significantly augments GEV release (by ~46%) as well as shifts the proteomic profile of these GEVs. Such shifts included enrichment of common EV-associated markers, downregulation of markers associated with cancer progression and resistance and modulation of inflammation-associated markers. When DCs were pulsed with GEVs, we noted that naïve GEVs suppressed IL-12p70 production by DCs in a GEV dose-dependent manner. In contrast, GEVs from cells exposed to FUS hyperthermia promoted a significant upregulation in IL-12p70 production by DCs, consistent with a pro-inflammatory stimulus. Conclusion: FUS hyperthermia triggers release of proteomically distinct GEVs that are capable of facilitating an important component of innate immune activation, lending both to a potential mechanism by which FUS interfaces with the tumor-immune landscape and to a role for GEV-associated biomarkers in monitoring response to FUS.