Blood-brain Barrier Function Research Articles

Biotinidase Deficiency and Aplasia Cutis Congenita with Ecterodactyly Syndrome (ACCES) in a case of Moya Moya Disease: A Missing Link

Biotinidase Deficiency (BD) is a rare autosomal recessive disorder caused by mutations in the BTD gene, leading to impaired biotin recycling and disruption in energy metabolism, oxidative stress, and blood-brain barrier function. This condition increases the risk of neurovascular events such as strokes. In parallel, the UBA2 gene's loss of function, through various mutations, results in Aplasia Cutis Congenita with Ectrodactyly (ACCES) syndrome, an autosomal dominant disorder with highly variable expressivity. ACCES syndrome commonly presents with scalp defects and less frequently with ectrodactyly, alongside other subtle skeletal anomalies, early growth deficiency, and neurodevelopmental delay. This case report discusses a 6-year-old child presenting with an acute stroke and distinct dysmorphic features, highlighting a rare association between Biotinidase Deficiency and ACCES syndrome, which likely contributed to the development of Moya Moya Disease (MMD), a rare progressive cerebrovascular disorder. The case suggests that the combination of neurovascular stress due to both BD and ACCES may increase the risk of stroke and MMD in affected individuals. This underscores the importance of recognizing overlapping genetic conditions that could lead to severe neurovascular complications.

Atp13a5 Marker Reveals Pericyte Specification in the Mouse Central Nervous System.

Perivascular mural cells including vascular smooth cells (VSMCs) and pericytes are integral components of the vascular system. In the central nervous system (CNS), pericytes are also indispensable for the blood-brain barrier (BBB), blood-spinal cord barrier, and blood-retinal barrier and play key roles in maintaining cerebrovascular and neuronal functions. However, the functional specifications of pericytes between CNS and peripheral organs have not been resolved at the genetic and molecular levels. Hence, the generation of reliable CNS pericyte-specific models and genetic tools remains very challenging. Here, we report a new CNS pericyte marker in mice. This putative cation-transporting ATPase 13A5 (Atp13a5) marker was identified through single-cell transcriptomics, based on its specificity to brain pericytes. We further generated a knock-in model with both tdTomato reporter and Cre recombinase. Using this model to trace the distribution of Atp13a5-positive pericytes in mice, we found that the tdTomato reporter reliably labels the CNS pericytes, including the ones in spinal cord and retina but not peripheral organs. Interestingly, brain pericytes are likely shaped by the developing neural environment, as Atp13a5-positive pericytes start to appear around murine embryonic day 15 (E15) and expand along the cerebrovasculature. Thus, Atp13a5 is a specific marker of CNS pericyte lineage, and this Atp13a5-based model is a reliable tool to explore the heterogeneity of pericytes and BBB functions in health and diseases.

Low-boiling-point perfluorocarbon nanodroplets for adaptable ultrasound-induced blood-brain barrier opening

Low-boiling point perfluorocarbon nanodroplets (NDs) are valued as effective sonosensitive agents, encapsulating a liquid perfluorocarbon that would instantaneously vaporize at body temperature without the NDs shell. Those NDs have been explored for both therapeutic and diagnostic purposes. Here, phospholipid-shelled nanodroplets containing octafluoropropane (C3F8) or decafluorobutane (C4F10) formed by condensation of microbubbles were thoroughly characterized before blood-brain (BBB) permeabilization. Transmission electron microscopy (TEM) and cryo-TEM were employed to confirm droplet formation while providing high-resolution insights into the droplet surface and lipid arrangement assessed from electron density observation after condensation. The vaporization threshold of NDs was determined with a high-speed camera, and the frequency signal emitted by the freshly vaporized bubbles was analyzed using cavitation detection. C3F8 NDs exhibited vaporization at 0.3 MPa (f0 = 1.5 MHz, 50 cycles), and emitted signals at 2 f0 and 1.5 f0 from 0.45 MPa onwards (f0 = 1.5 MHz, 50 cycles), while broadband noise was measured starting from 0.55 MPa. NDs with the higher boiling point C4F10 vaporized at 1.15 MPa and emitted signals at 2 f0 from 0.65 MPa and 1.5 f0 from 0.9 MPa, while broadband noise was detected starting from 0.95 MPa. Both ND formulations were used to permeabilize the BBB in healthy mice using tailored ultrasound sequences, allowing for the identification of optimal applications for each NDs type. C3F8 NDs proved suitable and safe for permeabilizing a large area, potentially the entire brain, at low acoustic pressure. Meanwhile, C4F10 droplets facilitated very localized (400 μm isotropic) permeabilization at higher pressure. This study prompts a closer examination of the structural rearrangements occurring during the condensation of microbubbles into NDs and highlights the potential to tailor solutions for different brain pathologies by choosing the composition of the NDs and adjusting the ultrasound sequence.

Protective Role of High-Density Lipoprotein in Multiple Sclerosis.

Multiple sclerosis (MS) is a chronic, progressive demyelinating disease with a most likely autoimmune background and a neurodegenerative component. Besides the demyelinating process caused by autoreactive antibodies, an increased permeability in the blood-brain barrier (BBB) also plays a key role. Recently, there has been growing interest in assessing lipid profile alterations in patients with MS. As a result of myelin destruction, there is an increase in the level of cholesterol released from cells, which in turn causes disruptions in lipid metabolism homeostasis both in the central nervous system (CNS) and peripheral tissues. Currently, there is a growing body of evidence suggesting a protective role of HDL in MS through its effect on the BBB by decreasing its permeability. This follows from the impact of HDL on the endothelium and its anti-inflammatory effect, mostly by interacting with adhesion molecules like vascular cell adhesion molecule 1 (VCAM-1), intercellular adhesion molecule 1 (ICAM-1), and E-selectin. HDL, through its action via sphingosine-1-phosphate, exerts an inhibitory effect on leukocyte migration, and its antioxidant properties contribute to the improvement of the BBB function. In this review, we want to summarize these studies and focus on HDL as a mediator of the anti-inflammatory response in MS.

Neuroprotective effects of Daphnetin on hippocampal neurons and blood-brain barrier integrity in a mouse model of cerebral ischemia

The purpose of this research was to assess the impact of different doses of Daphnetin (DAP, a natural compound derived from coumarin) on hippocampus neuronal injury, neurobehavioral function, blood-brain barrier (BBB) integrity, expression of claudin-5, brain-derived neurotrophic factor (BDNF), superoxide dismutase (SOD), and inflammatory markers in a mouse model of cerebral ischemia. Cerebral ischemia was induced in mice through 30 minutes of bilateral common carotid occlusion (BCCAO), followed by 48 hours of reperfusion. The viability of hippocampal neurons was assessed using Cresyl violet staining and BBB function was determined by measuring Evans blue (E.B) dye leakage. Spatial memory was tested using the Radial Arm Water Maze (RAWM) task. Claudin-5 and BDNF were measured by immunofluorescence, while SOD, interleukin-1 beta (IL-1β), and nuclear factor-κB (NF-κB) expression were determined through western blotting. Administering DAP significantly increased neuron survival in the hippocampus CA1, CA3, and dentate gyrus (DG) regions and improved spatial memory dose-dependently (P<0.0001). Treatment with DAP (40 mg/kg IP) significantly reduced E.B leakage and brain water content (P<0.001). Furthermore, it increased the claudin-5, BDNF, and SOD levels and diminished NF-κB and IL-1β expression (P<0.0001). The research found that DAP protected neurons in the CA1, CA3, and DG areas of the hippocampus, enhanced behavioral functions, and preserved BBB integrity in a cerebral ischemia model. This positive impact is achieved by increasing the expression of claudin-5, BDNF, and SOD and diminishing neuroinflammation. Further research is required to clarify the mechanisms and possible clinical uses.

Exploring the effects of moxibustion on cognitive function in rats with multiple cerebral infarctions from the perspective of glial vascular unit repairing.

This study aimed to explore the effect of moxibustion at Governor Vessel (GV) acupoints, including Baihui (GV 20), Shenting (GV 24) and Dazhui (GV 14) for 14days on glial vascular unit (GVU) in rats with multiple microinfarctions (MMI), and to explore its action mechanism. The effect and mechanism of moxibustion on vascular dementia (VD) were studied in MMI rats by means of behavioral and molecular biology experiments. Rats receiving MMI showed impairment of memory function, reduction of cerebral blood flow, damage of blood-brain barrier (BBB) integrity and increased brain mass. MMI also increased neuronal degeneration in the hippocampus. Notably, levels of glial fibrillary acidic protein (GFAP) and complement component 3 significantly increased, but those of Connexin43 (CX43) and platelet derived growth factor receptor β (PDGFRβ) significantly decreased in the hippocampus of the rats receiving MMI. Moxibustion, as well as oxiracetam (ORC) treatment improved memory function and neuronal degeneration, ameliorated BBB integrity, increased cerebral blood flow and decreased brain mass. In addition, moxibustion as well as oxiracetam (ORC) treatment reduced the decrease of CX43 protein and increased PDGFRβ protein level in the hippocampus of MMI rats. Moreover, moxibustion treatment reversed MMI-induced increase of the GFAP/CX43 ratio in vascular structural units. Importantly, after PDGFRβ inhibition, VD rats treated with moxibustion had impaired learning and memory, decreased cerebral blood flow, and BBB disruption. Moxibustion treatment at various GV acupoints improved cerebral blood flow and repaired BBB function in rats with MMI, likely through protecting GVU.

Enhancing Blood-Brain Barrier Integrity in Patients With Acute Ischemic Stroke Via Normobaric Hyperoxia.

Recent advancements in animal studies have demonstrated the potential of normobaric hyperoxia (NBO) as a promising intervention for preserving the integrity of the blood-brain barrier (BBB). However, there is still limited understanding of the effects of NBO on BBB function in patients with clinical stroke. Therefore, the objective of this study was to investigate the efficacy of NBO therapy in attenuating BBB damage and reducing brain injury in individuals undergoing endovascular treatment (EVT) for acute stroke. This study enrolled patients from the OPENS-1 (Normobaric Hyperoxia Combined With Reperfusion for Acute Ischemic Stroke) study, with 43 patients receiving NBO combined with EVT and 43 patients receiving EVT alone. The main outcome measures included serum levels of occludin, MMP-9 (matrix metalloproteinase-9), NSE (neuron-specific enolase), and S100b at 24 hours and 7 days, as well as the intracranial extravasation rate at 24 hours. Serum markers were assessed using ELISA, and intracranial contrast extravasation was visualized using dual-energy computed tomography scan. We analyzed a total of 86 patients and found that the 24-hour serum markers levels of BBB damage and brain injury were significantly lower in the group receiving NBO therapy combined with EVT compared with the group receiving EVT alone. Similarly, at 7 days, the levels of occludin, MMP-9, and NSE were lower in the NBO+EVT group. We also found that the 24-hour serum levels of occludin and MMP-9 were correlated with intracranial contrast extravasation. Additionally, the incidence of intracranial contrast extravasation was lower in the NBO+EVT group compared with the EVT group (35.9% versus 60.5%, P=0.031). This study offers valuable insights into the positive impact of NBO on maintaining BBB integrity and reducing brain injury in patients with acute stroke undergoing EVT.

Embryonic 6:2 Fluorotelomer Alcohol Exposure Disrupts the Blood‒Brain Barrier by Causing Endothelial‒to‒Mesenchymal Transition in the Male Mice.

6:2 Fluorotelomer alcohol (6:2 FTOH) is a raw material used in the manufacture of short-chain poly- and perfluoroalkyl substances. Our previous study revealed that gestational exposure to 6:2 FTOH can impair blood‒brain barrier (BBB) function in offspring, accompanied by anxiety-like behavior and learning memory deficits. The aim of this study was to further investigate the specific mechanism by which maternal exposure to 6:2 FTOH resulted in impaired BBB function in offspring mice. Pregnant mice were orally administered different doses of 6:2 FTOH (0, 5, 25, and 125mg/kg/day) from gestation day 8.5 until delivery. These results confirmed that maternal 6:2 FTOH exposure impaired BBB function and disrupted the brain immune microenvironment. Subsequent investigations revealed that endothelial-to-mesenchymal transition (EndMT) in the cerebral microvascular endothelium of offspring may be the mechanism mediating functional disruption of the BBB. Mechanistic studies revealed that exposure to 6:2 FTOH upregulated ETS proto-oncogene 1 (ETS1) expression via the tumor necrosis factor-α/extracellular signal-regulated kinase 1/2 signaling pathway, which mediated disturbances in energy metabolism, leading to impaired actin dynamics and subsequently triggering the EndMT phenotype. This is the first finding indicating that gestational 6:2 FTOH exposure caused functional impairment of the BBB through ETS1-mediated EndMT in cerebral microvascular endothelial cells, potentially providing novel insight into the environmental origins of neurodevelopmental disorders.

‘Selected’ Exosomes from Sera of Elderly Severe Obstructive Sleep Apnea Patients and Their Impact on Blood–Brain Barrier Function: A Preliminary Report

Obstructive sleep apnea syndrome (OSAS) affects a large part of the aging population. It is characterized by chronic intermittent hypoxia and associated with neurocognitive dysfunction. One hypothesis is that the blood–brain barrier (BBB) functions could be altered by exosomes. Exosomes are nanovesicles found in biological fluids. Through the study of exosomes and their content in tau and amyloid beta (Aβ), the aim of this study was to show how exosomes could be used as biomarkers of OSAS and of their cognitive disorders. Two groups of 15 volunteers from the PROOF cohort were selected: severe apnea (AHI &gt; 30) and control (AHI &lt; 5). After exosome isolation from blood serum, we characterized and quantified them (CD81, CD9, CD63) by western blot and ELISAs and put them 5 h in contact with an in vitro BBB model. The apparent permeability of the BBB was measured using sodium-fluorescein and TEER. Cell ELISAs were performed on tight junctions (ZO-1, claudin-5, occludin). The amount of tau and Aβ proteins found in the exosomes was quantified using ELISAs. Compared to controls, OSAS patients had a greater quantity of exosomes, tau, and Aβ proteins in their blood sera, which induced an increase in BBB permeability in the model and was reflected by a loss of tight junction’ expression. Elderly patients suffering severe OSAS released more exosomes in serum from the brain compartment than controls. Such exosomes increased BBB permeability. The impact of such alterations on the risk of developing cognitive dysfunction and/or neurodegenerative diseases is questioned.

Unraveling the neuroprotective potential of scalp electroacupuncture in ischemic stroke: A key role for electrical stimulation

This study aims to explore the neuroprotective effects of scalp Electroacupuncture (EA) on ischemic stroke, with a specific focus on the role of electrical stimulation (ES). Employing a rat model of middle cerebral artery occlusion (MCAO), we used methods such as Triphenyl tetrazolium chloride staining, micro-CT scanning, Enzyme linked immunosorbent assay (ELISA), and immunofluorescence to assess the impacts of EA. We further conducted RNA-seq analysis and in vitro experiments with organotypic brain slices and cerebral organoids to explore the underlying mechanisms. Our research revealed that EA notably reduced cerebral infarct volume and improved regional cerebral blood flow in rats following MCAO. Micro-CT imaging showed improved vascular integrity in EA-treated groups. Histological analyses, including HE staining, indicated reduced brain tissue damage. ELISA demonstrated a decrease in pro-inflammatory cytokines TNF-α, IL-1β, and IL-6, suggesting improved blood–brain barrier function. Immunofluorescence and Western blot analyses revealed that EA treatment significantly inhibited microglial and astrocytic overactivation. RNA-seq analysis of brain tissues highlighted a downregulation of immune pathways and inflammatory responses, confirming the neuroprotective role of EA. This was further corroborated by in vitro experiments using organotypic brain slices and cerebral organoids, which showcased the efficacy of electrical stimulation in reducing neuroinflammation and protecting neuronal cells. The study highlights the potential of scalp EA, particularly its ES component, in treating ischemic stroke. It provides new insights into the mechanisms of EA, emphasizing its efficacy in neuroprotection and modulation of neuroinflammation, and suggests avenues for optimized treatment strategies in stroke therapy.

A Human Brain-Chip for Modeling Brain Pathologies and Screening Blood–Brain Barrier Crossing Therapeutic Strategies

Background/Objectives: The limited translatability of preclinical experimental findings to patients remains an obstacle for successful treatment of brain diseases. Relevant models to elucidate mechanisms behind brain pathogenesis, including cell-specific contributions and cell-cell interactions, and support successful targeting and prediction of drug responses in humans are urgently needed, given the species differences in brain and blood-brain barrier (BBB) functions. Human microphysiological systems (MPS), such as Organ-Chips, are emerging as a promising approach to address these challenges. Here, we examined and advanced a Brain-Chip that recapitulates aspects of the human cortical parenchyma and the BBB in one model. Methods: We utilized human primary astrocytes and pericytes, human induced pluripotent stem cell (hiPSC)-derived cortical neurons, and hiPSC-derived brain microvascular endothelial-like cells and included for the first time on-chip hiPSC-derived microglia. Results: Using Tumor necrosis factor alpha (TNFα) to emulate neuroinflammation, we demonstrate that our model recapitulates in vivo-relevant responses. Importantly, we show microglia-derived responses, highlighting the Brain-Chip’s sensitivity to capture cell-specific contributions in human disease-associated pathology. We then tested BBB crossing of human transferrin receptor antibodies and conjugated adeno-associated viruses. We demonstrate successful in vitro/in vivo correlation in identifying crossing differences, underscoring the model’s capacity as a screening platform for BBB crossing therapeutic strategies and ability to predict in vivo responses. Conclusions: These findings highlight the potential of the Brain-Chip as a reliable and time-efficient model to support therapeutic development and provide mechanistic insights into brain diseases, adding to the growing evidence supporting the value of MPS in translational research and drug discovery.

Asymmetric dimethylarginine induces maladaptive function of the blood-brain barrier.

Growing body of evidence suggests that cardiovascular risk factor, asymmetric dimethylarginine (ADMA), can be implicated in the pathogenesis of neurodegenerative and psychiatric disorders. In part, ADMA can affect brain health negatively modulating critical functions of the blood-brain barrier (BBB). The precise mechanisms and consequences of ADMA action on the cerebral vasculature remains unexplored. Here, we evaluated ADMA-induced maladaptation of BBB functions by analyzing real time electrical cell-substrate impedance, paracellular permeability, immune-endothelial interactions, and inflammatory cytokines production by primary human brain microvascular endothelial cells (hBMVEC) treated with ADMA. We found that ADMA disrupted physical barrier function as evident by significant decrease in electrical resistance and increase in paracellular permeability of hBMVEC monolayers. Next, ADMA triggered immune-endothelial interactions since adhesion of primary human monocytes and their extravasation across the endothelial monolayer both were significantly elevated upon treatment with ADMA. Increased levels of cell adhesion molecules (VCAM-1 and RANTES), VEGF-A and inflammatory cytokines (IL-1β, TNF-α, IL-6, IL-10, IL-4, IL-2, IL-13, IL-12p70) characterize ADMA-induced hBMVEC dysfunction as inflammatory. Overall, our data suggest that ADMA can impair BBB functions disrupting the endothelial barrier and eliciting neuroinflammatory and neuroimmune responses.

Proteomic analysis and experimental validation reveal the blood–brain barrier protective of Huanshaodan in the treatment of SAMP8 mouse model of Alzheimer’s disease

BackgroundHuanshaodan (HSD) is a Chinese Herbal Compound which has a definite clinical effect on Alzheimer’s disease (AD), however, the underlying mechanism remains unclear. The aim of this study is to preliminarily reveal the mechanism of HSD in the treatment of AD model of SAMP8 mice.MethodsChemical composition of HSD and its drug-containing serum were identified by Q-Orbitrap high resolution liquid mass spectrometry. Six-month-old SAMP8 mice were treated with HSD and Donepezil hydrochloride by gavage for 2 months, and Wogonin for 28 days. Behavioral test was performed to test the learning and memory ability of mice. Immunofluorescence (IF) or Western-blot methods were used to detect the levels of pSer404-tau and β-amyloid (Aβ) in the brain of mice. Hematoxylin–eosin (H&E) staining and Transmission electron microscopy (TEM) assay was applied to observe the pathological changes of neurons. Proteomic technology was carried out to analyze and identify the protein network of HSD interventions in AD. Then the pathological process of the revealed AD-related differential proteins was investigated by IF, Q-PCR, Western-blot, Fluorescence in situ hybridization (FISH) and 16S rRNA sequencing methods.ResultsThe results showed that HSD and Wogonin, one of the components in its drug-containing serum, can effectively improve the cognitive impairments of SAMP8 mice, protect hippocampal neurons and synapses, and reduce the expression of pSer404-tau and Aβ. HSD and Wogonin reduced the levels of fibrinogen β chain (FGB) and γ chain (FGG), the potential therapeutic targets revealed by proteomics analysis, reduced the colocalization of FGB and FGG with Aβ, ionized calcium binding adaptor molecule 1 (Iba-1), glial fibrillary acidic protein (GFAP), increased level of and myelin basic protein (MBP). Meanwhile, HSD and Wogonin increased ZO-1 and Occludin levels, improved brain microvascular injury, and reduced levels of bacteria/bacterial DNA and lipopolysaccharide (LPS) in the brain of mice. In addition, 16S rRNA sequencing indicated that HSD regulated the structure of intestinal microbiota of mice.ConclusionThe effects of HSD on AD may be achieved by inhibiting the levels of fibrinogen and the interactions on glia cells in the brain, and by modulating the structure of intestinal microbiota and improving the blood–brain barrier function.

Salidroside improves blood-brain barrier integrity and cognitive function in hypobaric hypoxia mice by inhibiting microglia activation through GSK3β.

Salidroside, an active component found in Rhodiola rosea L., has emerged as a potential therapeutic agent for the prevention and treatment of hypoxic brain injury, while the precise target and mechanism of salidroside were remain unclear. The study utilized techniques such as network pharmacology, transcriptome sequencing to investigate the mechanism and target of salidroside in regulating blood-brain barrier (BBB) function to protect hypoxic brain injury in vivo. Utilized macromolecular docking and molecular biology techniques to explore the molecular mechanism of salidroside in alleviating brain injury induced by hypoxia in BV2 cell model. The results show that salidroside alleviated the learning and memory dysfunction and pathological injury in mice exposed to hypobaric hypoxia, reduced brain water content and attenuate the inflammatory response and oxidative stress, effectively reversed S100β in serum and promoted the repair of BBB. GSK3β is an important therapeutic target of salidroside in the treatment of hypoxic cognitive impairment, and salidroside can specifically bind GSK3β in the ATP binding pocket, inducing the phosphorylation of GSK3β, targeting downstream Nrf-2 to regulate microglia activity, promoting the accumulation of β-catenin, thereby inhibiting microglial activation, improving the BBB integrity injury and achieving a neuroprotective effect. This study demonstrates that salidroside can inhibit the activation of microglia by inducing GSK3β phosphorylation, achieve neuroprotective effects and alleviate learning and memory dysfunction in hypobaric hypoxia mice. This study provides a theoretical basis for the development of salidroside and the clinical application of Rhodiola rosea L.

Feasibility of Hologram-Assisted Bilateral Blood-Brain Barrier Opening in Non-Human Primates.

Focused ultrasound (FUS) and microbubbles facilitate blood-brain barrier opening (BBBO) noninvasively, transiently, and safely for targeted drug delivery. Unlike state-of-the-art approaches, in this study, we demonstrate for the first time the simultaneous, bilateral BBBO in non-human primates (NHPs) using acoustic holograms at caudate and putamen structures. The simple and low-cost system with a single-element FUS transducer and 3-D printed acoustic hologram was guided by neuronavigation and a robotic arm. The advantages of holograms are transcranial aberration correction, simultaneous multifocus and high localization, and target-independent transducer positioning, defining a promising alternative for time- and cost-efficient FUS procedures. Holograms were designed with the k-space method by time-reversal techniques. T1-weighted MRI was used for treatment planning, while the computed tomography (CT) scan provided the head tissues acoustic properties. For the BBBO procedure, a robotic arm allowed transducer positioning errors below 0.1 mm and 0.1°. Following positioning, 0.5-0.6-MPa, 513-kHz microbubble-enhanced FUS was applied for 4 min. For BBBO assessment, Post-FUS T1-weighted MRI was acquired, and contrast enhancement indicated bilateral gadolinium extravasation at both caudate or putamen structures. The two BBBO locations were separated by 13.13 mm with a volume of 91.81 mm3 in the caudate, compared with 9.40 mm with a volume of 124.52 mm3 in simulation, while they were separated by 21.74 mm with a volume of 145.38 mm3 in the putamen and compared with 22.32 mm with a volume of 156.42 mm3 in simulation. No neurological damage was observed through T2-weighted and susceptibility-weighted imaging. This study demonstrates the feasibility and safety of hologram-assisted neuronavigation-guided-FUS for BBBO in NHP, providing thus an avenue for clinical translation.

A comprehensive numerical investigation of the potential influence of the bubble size and ultrasound focal pressure in drug delivery enhancement

Stable Bubble oscillations contribute to a range of bio-effects such as enhanced drug delivery and blood-brain barrier opening. The treatment outcome depends on the bubble oscillation characteristics and the number of bubbles present at the target. Higher concentrations result in more bubbles per unit length of the vessels and, therefore, more uniform effects. At higher bubble concentrations, however, the pre-focal attenuation increases. Moreover, above a concentration threshold, bubble-bubble interactions suppress bubble oscillations. To enhance the treatment outcome, thus, not only the bubble concentration and activity should be optimized, but also the problem of pre-focal attenuation should be tackled. Numerical results show that, using the pressure gradient of focused ultrasound transducers and by taking advantage of the pressure dependent attenuation of size isolated bubbles, pre-focal attenuation can be minimized. The optimal bubble size for maximum propagation depends on the focal pressure. When volume is matched, and at lower pressures, bigger bubbles exhibit stronger radial oscillations, scattered pressure, and microstreaming (RSM). Above a pressure threshold that depend on the bubble size, smaller bubbles exhibit stronger RSM compared to their bigger counterparts. The treatment outcome may be enhanced using an optimal set of size and pressures. These results are in qualitative agreement with experimental case studies using size isolated bubbles.

Protective Effect of Protocatechuic Aldehyde on Cerebral Ischemia/Reperfusion Injury in Rats through Blood-Brain Barrier Protection.

Cerebral ischemia can lead to destruction of the blood-brain barrier (BBB), the main cause of cerebral edema and cerebral infarction. BBB damage is also one of the key factors affecting the result of drug therapy. We studied the protective effect of 5-day pretreatment with protocatechuic aldehyde (PAL) at doses of 10 and 20 mg/kg on BBB function and structure after middle cerebral artery occlusion/reperfusion (MCAO/R) in rats. The infarct volume, behavioral neurological deficit score, and Evans blue content in the brain were estimated. We also evaluated the content of nitric oxide (NO) and activities of inducible and neuronal NO synthases. Expression of aquaporin-4 (AQP-4), occludin, claudin-5, and MMP-3 in the brain tissues was estimated by Western blotting. The BBB ultrastructure was analyzed under an electron microscope. We revealed that PAL at both used doses significantly reduced the neurological deficit score, brain infarct volume, and Evans blue extravasation. Electron microscopy showed that PAL significantly improved the ultrastructure of BBB and alleviated its injury. Pretreatment with PAL increased expression of occludin and claudin-5 and reduced expression of AQP-4 and MMP-3. At the same time, the release of NO and activities of NO synthases were notably inhibited. Our results suggest that PAL can be a promising compound to attenuate cerebral ischemia resulting from occlusion/reperfusion injury via BBB protection.

Message in a bubble: Methods and uses of passive cavitation detection and passive acoustic mapping

An ever-growing body of clinical evidence demonstrates the profound impact of cavitation-based therapies on a wide variety of human pathologies. A key part of these evolving therapeutic techniques is the ability to detect, characterize, and quantify cavitation activity. In this session, we will describe the physical principles, devices, and algorithms for passive cavitation detection and mapping, with demonstrations and specific examples drawn from preclinical and clinical data. Finally, we will discuss the concept of cavitation dose and its distinct implementations for blood brain barrier opening, abdominal organ drug delivery, and histotripsy. The tutorial will include data and MATLAB code so that all attendees may play along.

Comparing the delivery of free and liposomal-encapsulated doxorubicin across the blood-brain barrier with microbubble-mediated focused ultrasound

This work investigates the effect of drug formulation (free, small molecule drug or liposomal-encapsulated nanoparticle) on Focused Ultrasound (FUS) and microbubble-mediated delivery of doxorubicin (Dox) across the blood-brain barrier (BBB) in healthy and F98 tumor-bearing rats. Dox is auto-fluorescent (Ex: 470 nm; Em: 560 nm). 1, 4, and 24 h after FUS and the administration of Dox, brain samples were collected and homogenized, and the concentration of Dox was measured using a fluorometer. In healthy brains, at 1, 4 and 24 h, FUS significantly increased the delivery of both formulations (p&amp;lt;0.05). At 1 h, the mean concentration of Dox was 47% more in the striatum (p = 0.010) and 51% more in the hippocampus (n.s.; p = 0.072) compared to Lipo Dox. No differences in Dox versus Lipo Dox delivery were observed at 4 and 24 h. In F98 tumors, at 1 and 24 h, FUS significantly increased the concentrations of both formulations (p&amp;lt;0.05). No significant difference was observed in the concentrations of Dox and Lipo Dox at 1 h (p = 0.291). However, at 24 h, 96% higher drug concentrations were measured in tumors in animals that received Lipo Dox compared to Dox (p = 0.045). The results of this study may have important implications for drug selection in clinical applications of FUS-mediated BBB opening.

Anatomically and Physiologically Accurate Engineered Neurovascular Unit and Blood-Brain Barrier Model Using Microvessels Isolated from Postmortem Human Brain Tissue.

Brain vasculature is a complex and heterogeneous physiological structure that serves specialized roles in maintaining brain health and homeostasis. There is substantial interest in developing representative human models of the brain vasculature for drug screening and disease modeling applications. Many contemporary strategies have focused on culturing neurovascular cell types in hydrogels and microdevices, but it remains challenging to achieve anatomically relevant vascular structures that have physiologically similar function to their in vivo counterparts. Here, we present a strategy for isolating microvessels from cryopreserved human cortical tissue and culturing these vessels in a biomimetic gelatin-based hydrogel contained in a microfluidic device. We provide histological evidence of arteriole and capillary architectures within hydrogels, as well as anastomosis to the hydrogel edges allowing lumen perfusion. In capillaries, we demonstrate restricted diffusion of a 10 kDa dextran, indicating intact passive blood-brain barrier function. We anticipate this bona fide human brain vasculature-on-a-chip will be useful for various biotechnology applications.