Pericytes control key neurovascular functions and neuronal phenotype in the adult brain and during brain aging

Interaction of major facilitator superfamily domain containing 2A with the blood-brain barrier

The functional and structural integrity of the blood-brain barrier is crucial in maintaining homeostasis in the brain microenvironment; however, the molecular mechanisms underlying the formation and function of the blood-brain barrier remain poorly understood. The major facilitator superfamily domain containing 2A has been identified as a key regulator of blood-brain barrier function. It plays a critical role in promoting and maintaining the formation and functional stability of the blood-brain barrier, in addition to the transport of lipids, such as docosahexaenoic acid, across the blood-brain barrier. Furthermore, an increasing number of studies have suggested that major facilitator superfamily domain containing 2A is involved in the molecular mechanisms of blood-brain barrier dysfunction in a variety of neurological diseases; however, little is known regarding the mechanisms by which major facilitator superfamily domain containing 2A affects the blood-brain barrier. This paper provides a comprehensive and systematic review of the close relationship between major facilitator superfamily domain containing 2A proteins and the blood-brain barrier, including their basic structures and functions, cross-linking between major facilitator superfamily domain containing 2A and the blood-brain barrier, and the in-depth studies on lipid transport and the regulation of blood-brain barrier permeability. This comprehensive systematic review contributes to an in-depth understanding of the important role of major facilitator superfamily domain containing 2A proteins in maintaining the structure and function of the blood-brain barrier and the research progress to date. This will not only help to elucidate the pathogenesis of neurological diseases, improve the accuracy of laboratory diagnosis, and optimize clinical treatment strategies, but it may also play an important role in prognostic monitoring. In addition, the effects of major facilitator superfamily domain containing 2A on blood-brain barrier leakage in various diseases and the research progress on cross-blood-brain barrier drug delivery are summarized. This review may contribute to the development of new approaches for the treatment of neurological diseases.

Neuropathological links between T2DM and LOAD: systematic review and meta-analysis

Recent decades have described parallel neuropathological mechanisms increasing the risk for developing late-onset Alzheimer's dementia (LOAD) in type 2 diabetes mellitus (T2DM); however, still little is known of the role of diabetic encephalopathy and brain atrophy in LOAD. The aim of this systematic review is to provide a comprehensive view on diabetic encephalopathy/cerebral atrophy, taking into account neuroimaging data, neuropathology, metabolic and endocrine mechanisms, amyloid formation, brain perfusion impairments, neuroimmunology, and inflammasome activation. Key switches were identified, to further meta-analyze genomic candidate loci and epigenetic modifications. For the qualitative meta-analysis of genomic bases extracted, human linkage studies were examined; for epigenetic mechanisms, data from both human and animal studies are described. For the systematic review of pathophysiological mechanisms, 1,259 publications were evaluated and 93 gene loci extracted for candidate risk linkages. Sixty-six publications were evaluated for genomic association and descriptions of epigenomic modifications. Overall accumulated results highlight the insulin signaling system, vascular markers, inflammation and inflammasome pathways, amylin interactions, and glycosylation mechanisms. The protocol was registered with PROSPERO (ID: CRD42023440535).

Advanced nanoparticle engineering for precision therapeutics of brain diseases

Despite the increasing global prevalence of neurological disorders, the development of nanoparticle (NP) technologies for brain-targeted therapies confronts considerable challenges. One of the key obstacles in treating brain diseases is the blood-brain barrier (BBB), which restricts the penetration of NP-based therapies into the brain. To address this issue, NPs can be installed with specific ligands or bioengineered to boost their precision and efficacy in targeting brain-diseased cells by navigating across the BBB, ultimately improving patient treatment outcomes. At the outset of this review, we highlighted the critical role of ligand-functionalized or bioengineered NPs in treating brain diseases from a clinical perspective. We then identified the key obstacles and challenges NPs encounter during brain delivery, including immune clearance, capture by the reticuloendothelial system (RES), the BBB, and the complex post-BBB microenvironment. Following this, we overviewed the recent progress in NPs engineering, focusing on ligand-functionalization or bionic designs to enable active BBB transcytosis and targeted delivery to brain-diseased cells. Lastly, we summarized the critical challenges hindering clinical translation, including scalability issues and off-target effects, while outlining future opportunities for designing cutting-edge brain delivery technologies.

Sex-dependent blood-brain barrier alterations following repeated mild blast traumatic brain injury at varying inter-injury intervals

BACKGROUND

Traumatic brain injury (TBI) is a worldwide epidemic and a major cause of disability, morbidity, and mortality. TBI is a major risk factor for the development of late-life dementia, especially Alzheimer's Disease, and other neurological conditions, such as epilepsy. The most prevalent form of TBI is mild TBI (mTBI), which is characterized by cognitive and psychological deficits as well as metabolic and vascular mechanisms of neuropathobiology. mTBI can be induced by either impact or blast insults and multiple mTBIs can result in worsened outcomes. There is a need to understand pathological impairments in the blood-brain barrier (BBB) following mTBI.

METHODS

To model repeated mild blast traumatic brain injury (rmbTBI), male and female rats (N = 6/group) were exposed to repeated low-level, 11 psi static peak overpressure blast waves using the McMillan blast device. rmbTBI was produced with either 1 h or 24 h inter-injury interval. Sham animals undergo all procedures except for the blast. Animals performed open field and elevated plus maze (EPM) behavior tests before euthanasia at 7d post-rmbTBI. Hemibrains were taken separately for immunohistochemistry and western blot analysis. Brain capillaries were isolated from fresh brain tissue and taken for immunofluorescent (IF) staining.

RESULTS

To examine BBB-specific deficits, pericyte (PDGFRβ), tight junction (TJ) protein (zonula occludens-1 (ZO1), occludin and Claudin-5), astrocytic end-feet (AQP4), and BBB integrity (SMI-71) markers were analyzed at 7d post-rmbTBI. Deficits in cortical AQP-4 and SMI-71 levels were observed in male rmbTBI-24 h group compared to sham while female rmbTBI groups displayed no deficits in these markers compared to sham. There were deficits in TJ markers in both male rmbTBI groups that were not apparent in female-derived capillaries. Western blot analysis demonstrates that PDGFRβ is significantly decreased in male rmbTBI-24 h animals but not male rmbTBI-1 h or female rmbTBI animals. Male rmbTBI-1 h group displayed lower levels of GFAP and higher levels of IBA-1 in the cortex as compared to sham; female rmbTBI groups displayed similar levels of cortical GFAP and IBA-1 as sham. Male rmbTBI and female 1 h-interval rmbTBI groups displayed significantly higher closed arm entrances during EPM as compared to respective sham groups.

CONCLUSION

Our findings demonstrate that rmbTBI produces robust on-going deficits in BBB and glial outcomes that correspond with behavioral abnormalities in male animals. The extent of these outcomes is dependent upon inter-injury interval. Female rmbTBI animals display anxiety-related behavior that is not driven by BBB-related impairments.

Pericytes in the Optic Nerve Head

Pericytes are a unique population of contractile mural cells and an essential part of the microvasculature. In the retina and brain, pericytes play crucial roles in regulating blood flow, maintaining the blood-brain barrier, signaling with neighboring cells, and depositing extracellular matrix. Pericyte dysfunction is an early process in a variety of neurodegenerative conditions. However, remarkably little is known about pericytes at an early site of neurodegeneration in glaucoma, the optic nerve head (ONH). This work summarizes the current understanding of pericyte contributions to ONH physiology, identifies potential roles in glaucomatous pathophysiology, and uncovers open questions at the intersection of these areas. We surveyed the literature to identify the roles of ONH pericytes in the context of health and glaucoma. Additionally, we probed for the presence of pericytes along microvasculature in mouse, nonhuman primate, and human donor ONH tissues. We identified an association between factors influencing ONH dysfunction in glaucoma and factors influencing pericyte dysfunction in other neurodegenerative conditions. Pericytes exist in the mouse, nonhuman primate, and human ONH, implicating their capacity for local function. ONH pericytes represent a promising but underexplored target for treating microvascular impairment in glaucoma. Investigating the contribution of pericytes in both healthy and disease states can help inform mechanisms of dysfunction in glaucomatous pathology, paving the way for the development of novel therapeutic strategies.

Brain remodeling in stroke patients: A comprehensive review of mechanistic and neuroimaging studies

Stroke-induced brain remodeling involves a complex interplay of neurovascular components, including endothelial cells, microglia, astrocytes, and pericytes, which collectively contribute to the restoration of brain function. These processes are crucial for repairing the blood-brain barrier, regulating inflammation, and promoting neurogenesis. This review examines the mechanisms underlying brain remodeling and the role of advanced neuroimaging techniques-such as functional MRI (fMRI), positron emission tomography (PET), functional near-infrared spectroscopy (fNIRS), and functional ultrasound (fUS)-in assessing these changes. We also discuss various therapeutic approaches aimed at enhancing brain remodeling, including pharmacological agents, stem cell therapy, and rehabilitation strategies that target neurovascular repair and functional recovery. Despite significant progress, challenges remain in translating imaging insights into effective treatments. Future research should focus on integrating multiple imaging modalities to provide a comprehensive view of neurovascular changes and refining therapeutic interventions to optimize recovery and functional outcomes in stroke patients.

Pericyte Biomarkers for Ischemic Stroke: Potential and Prospects

Ischemic stroke (IS) has a high mortality rate. Multiplexed detection of IS core biomarkers is of great significance to early diagnosis and personalized treatment of IS patients. Whether pericytes, a key component of the neurovascular unit and blood-brain barrier located on the capillary wall, could serve as a promising biomarker for IS is to be explored. Herein, we observed a significant upregulation of inflammatory and apoptotic factors, such as MMP9, in pericytes subjected to in vitro ischemia. By transfecting pericytes with ASK1-shRNA to inhibit ASK1 expression, we noted reduced levels of inflammatory and apoptotic markers, including MMP9, as well as enhanced pericyte contraction and migration, thereby preserving the integrity of the blood-brain barrier. Additionally, ELISA assays conducted using plasma samples from patients with varying NIHSS scores revealed statistically significant concentrations of PDGFRβ and MMP9. Furthermore, we developed a highly sensitive and specific quantitative detection method for PDGFRβ and MMP9 based on fluorescence sensor technology. This novel detector exhibits high sensitivity, repeatability, and stability, enabling precise dual detection. Thus, the results suggest the great potential of the detection of PDGFRβ and MMP9 for early diagnosis of IS and prognosis prediction of the disease.

The Blood-Brain Barrier: Composition, Properties, and Roles in Brain Health

Blood vessels are critical to deliver oxygen and nutrients to tissues and organs throughout the body. The blood vessels that vascularize the central nervous system (CNS) possess unique properties, termed the blood-brain barrier (BBB), which allow these vessels to tightly regulate the movement of ions, molecules, and cells between the blood and the brain. This precise control of CNS homeostasis allows for proper neuronal function and protects the neural tissue from toxins and pathogens, and alterations of this barrier are important components of the pathogenesis and progression of various neurological diseases. The physiological barrier is coordinated by a series of physical, transport, and metabolic properties possessed by the brain endothelial cells (ECs) that form the walls of the blood vessels. These properties are regulated by interactions between different vascular, perivascular, immune, and neural cells. Understanding how these cell populations interact to regulate barrier properties is essential for understanding how the brain functions in both health and disease contexts.

The microcirculation, the blood-brain barrier, and the neurovascular unit in health and Alzheimer disease: The aberrant pericyte is a central player

High fidelity neuronal signaling is enabled by a stable local microenvironment. A high degree of homeostatic regulation of the brain microenvironment, and its separation from the variable and potentially neurotoxic contents of the blood, is brought about by the central nervous system barriers. Evidence from clinical and preclinical studies implicates brain microcirculation, cerebral hypoperfusion, blood-brain barrier dysfunction, and reduced amyloid clearance in Alzheimer pathophysiology. Studying this dysregulation is key to understanding Alzheimer disease (AD), identifying drug targets, developing treatment strategies, and improving prescribing to this vulnerable population. This review has 2 parts: part 1 describes the cerebral microcirculation, cerebral blood flow, extracellular fluid drainage, and the neurovascular unit components with an emphasis on the blood-brain barrier, and part 2 summarizes how each aspect is altered in AD. Discussing the neurovascular unit structures separately allows us to conclude that aberrant pericytes are an early contributor and central to understanding AD pathophysiology. Pericytes have multiple functions including maintenance of blood-brain barrier integrity and the control of capillary blood flow, capillary stalling, neurovascular coupling, intramural periarterial drainage, glia-lymphatic (glymphatic) drainage, and consequently amyloid and tau clearance. Pericytes are vasoactive, express cholinergic and adrenergic receptors, and exhibit apolipoprotein E isoform-specific transport pathways. Hypoperfusion in AD is linked to a pericyte-mediated response. Deficient endothelial cell-pericyte (PDGBB-PDGFRβ) signaling loops cause pericyte dysfunction, which contributes and even initiates AD degeneration. We conclude that pericytes are central to understanding AD pathophysiology, are an interesting therapeutic target in AD, and have an emerging role in regenerative therapy. SIGNIFICANCE STATEMENT: Dysregulation and dysfunction of the neurovascular unit and fluid circulation (including blood, cerebrospinal fluid, and interstitial fluid) occurs in Alzheimer disease. A central player is the aberrant pericyte. This has fundamental implications to understanding disease pathophysiology and the development of therapies.

Research developments in the neurovascular unit and the blood‑brain barrier (Review)

The neurovascular unit (NVU) is composed of neurons, glial cells, brain microvascular endothelial cells (BMECs), pericytes, and the extracellular matrix. The NVU controls the permeability of the blood-brain barrier (BBB) and protects the brain from harmful blood-borne and endogenous and exogenous substances. Among these, neurons transmit signals, astrocytes provide nutrients, microglia regulate inflammation, and BMECs and pericytes strengthen barrier tightness and coverage. These cells, due to their physical structure, anatomical location, or physiological function, maintain the microenvironment required for normal brain function. In this review, the BBB structure and mechanisms are examined to obtain a better understanding of the factors that influence BBB permeability. The findings may aid in safeguarding the BBB and provide potential therapeutic targets for drugs affecting the central nervous system.

Unlocking the potential of photobiomodulation therapy for brain neurovascular coupling: The biological effects and medical applications

Photobiomodulation (PBM) therapy stands as an innovative neurostimulation modality that has demonstrated both efficacy and safety in improving brain function. This therapy exerts multifaceted influences on neurons, blood vessels, and their intricate interplay known as neurovascular coupling (NVC). Growing evidence indicates that NVC may present a promising target for PBM intervention. However, the detailed mechanisms underlying its therapeutic benefits remain to be fully understood. This review aims to elucidate the potential metabolic pathways and signaling cascades involved in the modulatory effects of PBM, while also exploring the extensive repertoire of PBM applications in neurologic and psychiatric conditions. The prospects of PBM within the realm of NVC investigation are intensively considered, providing deeper insights into the powerful capabilities of PBM therapy and its potential to revolutionize neurostimulation treatments.

Krüppel-like factor 4 transcription factor in blood-brain barrier endothelial cells: A potential role in Alzheimer's disease

Alzheimer's disease is the most prevalent chronic neurodegenerative disorder worldwide, with no sufficient cure. Ongoing research is focused on developing new therapies aimed at preventing or delaying the onset of symptoms, slowing disease progression, and improving cognitive and behavioral outcomes in individuals affected by Alzheimer's disease. Among the various pathological changes associated with this condition, blood-brain barrier (BBB) leakage plays a crucial role as it serves as a vital boundary for maintaining central nervous system (CNS) health. Preserving the integrity and functionality of the BBB is essential to protect the brain from amyloid-β accumulation, neuroinflammation, and neuronal degeneration. This review summarizes models of Alzheimer's disease characterized by BBB leakage over time. More importantly, we introduce Krüppel-like factor 4 (KLF4), a transcription factor involved in vascular systems, and discuss its relevance to Alzheimer's disease. By elucidating the functions of KLF4 within both vascular and CNSs, this review highlights its potential role in modulating BBB integrity in Alzheimer's pathology, which may contribute to therapeutic strategies for managing this debilitating condition.

Nanoparticles Designed Based on the Blood-Brain Barrier for the Treatment of Cerebral Ischemia-Reperfusion Injury

Cerebral ischemia-reperfusion injury (CI/RI) is currently considered a significant factor affecting the prognosis of ischemic stroke. The blood-brain barrier (BBB) plays multiple roles in the treatment ofCI/RI. BBB leakage allows bloodborne toxins to exacerbate the stroke pathology. Yet as the physiological barrier that separates the blood from the brain, BBB also poses a significant obstacle to therapeutic drug delivery. Therefore, it is essential to consider both crossing and repairing the BBB in the process of the treatment of CI/RI. Leveraging the exceptional benefits of nanoparticles (NPs) for BBB penetration and targeted repair, numerous NPs are developed as promising drug delivery platforms. Considering the complex role of the BBB in CI/RI, this review delves into the strategies for designing NPs to cross the BBB, focusing on peptide-modified NPs, cell-mediated NPs, cell membrane-derived NPs, and BBB-modulating NPs. Additionally, it summarizes design strategies of NPs targeting endothelial cells (ECs), astrocytes, and those aimed at regulating the microenvironment to repair the BBB. On this basis, it reveals the prospects and challenges of NPs designed around the BBB in CI/RI treatment. And it highlights the need to combine BBB permeability promotion and BBB repair in nanoparticle strategies designed based on the BBB to achieve more effective treatment.

The blood-brain barrier as a treatment target for neurodegenerative disorders

INTRODUCTION

The blood-brain barrier (BBB) is a vascular endothelial membrane which restricts entry of toxins, cells, and microorganisms into the brain. At the same time, the BBB supplies the brain with nutrients, key substrates for DNA and RNA synthesis, and regulatory molecules, and removes metabolic waste products from brain to blood. BBB breakdown and/or dysfunction have been shown in neurogenerative disorders including Alzheimer's disease (AD). Current data suggests that these BBB changes may initiate and/or contribute to neuronal, synaptic, and cognitive dysfunction, and possibly other aspects of neurodegenerative processes.

AREAS COVERED

We first briefly review recent studies uncovering molecular composition of brain microvasculature and examine the BBB as a possible therapeutic target in neurodegenerative disorders with a focus on AD. Current strategies aimed at protecting and/or restoring altered BBB functions are considered. The relevance of BBB-directed approaches to improve neuronal and synaptic function, and to slow progression of neurodegenerative processes are also discussed. Lastly, we review recent advancements in drug delivery across the BBB.

EXPERT OPINION

BBB breakdown and/or dysfunction can significantly affect neuronal and synaptic function and neurodegenerative processes. More attention should focus on therapeutics to preserve or restore BBB functions when considering treatments of neurodegenerative diseases and AD.

Molecular signature and functional properties of human pluripotent stem cell-derived brain pericytes

Brain pericytes maintain the blood-brain barrier (BBB), secrete neurotrophic factors and clear toxic proteins. Their loss in neurological disorders leads to BBB breakdown, neuronal dysfunction, and cognitive decline. Therefore, cell therapy to replace lost pericytes holds potential to restore impaired cerebrovascular and brain functions. However, the molecular composition and function of human iPSC-derived brain pericytes (iPSC-PC) remains poorly characterized. Here, we show by a quantitative analysis of 8,344 proteins and 20,572 phosphopeptides that iPSC-PC share 96% of total proteins and 98% of protein phosphorylation sites with primary human brain pericytes. This includes cell adhesion and tight junction proteins, transcription factors, and different protein kinase families of the human kinome. In pericyte-deficient mice, iPSC-PC home to host brain capillaries to form hybrid human-mouse microvessels with ligand-receptor associations. They repair BBB leaks and protect against neuron loss, which we show requires PDGRFB and pleiotrophin. They also clear Alzheimer's amyloid-β and tau neurotoxins via lipoprotein receptor. Thus, iPSC-PC may have potential as a replacement therapy for pericyte-deficient neurological disorders.

The role of the RING finger protein 213 gene in Moyamoya disease

Moyamoya Disease (MMD) represents a chronic and progressive cerebrovascular disorder characterized by the gradual occlusion of the terminal portions of the bilateral internal carotid arteries and their major branches, accompanied by the formation of abnormal vascular networks at the base of the skull. In adolescents, particularly in pediatric populations, MMD is a significant cause of stroke, posing a severe challenge to human health and imposing a heavy burden on healthcare systems. Ring Finger Protein 213 (RNF213), as the primary susceptibility gene for MMD, plays a crucial regulatory role in the initiation, progression, and prognosis of the disease. Despite extensive research on the role of RNF213 in the pathogenesis of MMD, the underlying molecular mechanisms remain incompletely understood and represent a pressing scientific challenge requiring further exploration. This review aims to synthesize the latest research findings and systematically elucidate the multifaceted roles of RNF213 in MMD, including genetic susceptibility, immune-inflammatory responses, blood-brain barrier(BBB) disruption, and angiogenesis. By integrating these findings, this study seeks to provide new insights and theoretical support for a comprehensive and in-depth understanding of the pathophysiological processes of MMD. This research not only contributes to further unraveling the complex pathogenesis of MMD but also lays a solid theoretical foundation for the development of targeted preventive and therapeutic strategies.

Pericytes in the brain and heart: functional roles and response to ischaemia and reperfusion

In the last 20 years, there has been a revolution in our understanding of how blood flow is regulated in many tissues. Whereas it used to be thought that essentially all blood flow control occurred at the arteriole level, it is now recognized that control of capillary blood flow by contractile pericytes plays a key role both in regulating blood flow physiologically and in reducing it in clinically relevant pathological conditions. In this article, we compare and contrast how brain and cardiac pericytes regulate cerebral and coronary blood flow, focusing mainly on the pathological events of cerebral and cardiac ischaemia. The cerebral and coronary capillary beds differ dramatically in morphology, yet in both cases, pericyte-mediated capillary constriction plays a key role in restricting blood flow after ischaemia and possibly in other pathological conditions. We conclude with suggestions for therapeutic approaches to relaxing pericytes, which may prove useful in the long-term for reducing pericyte-induced ischaemia.

Cell-based regenerative and rejuvenation strategies for treating neurodegenerative diseases

Neurodegenerative diseases including Alzheimer's and Parkinson's disease are age-related disorders which severely impact quality of life and impose significant societal burdens. Cellular senescence is a critical factor in these disorders, contributing to their onset and progression by promoting permanent cell cycle arrest and reducing cellular function, affecting various types of cells in brain. Recent advancements in regenerative medicine have highlighted "R3" strategies-rejuvenation, regeneration, and replacement-as promising therapeutic approaches for neurodegeneration. This review aims to critically analyze the role of cellular senescence in neurodegenerative diseases and organizes therapeutic approaches within the R3 regenerative medicine paradigm. Specifically, we examine stem cell therapy, direct lineage reprogramming, and partial reprogramming in the context of R3, emphasizing how these interventions mitigate cellular senescence and counteracting aging-related neurodegeneration. Ultimately, this review seeks to provide insights into the complex interplay between cellular senescence and neurodegeneration while highlighting the promise of cell-based regenerative strategies to address these debilitating conditions.

Ex Vivo Plasma Application on Human Brain Microvascular Endothelial-like Cells for Blood-Brain Barrier Modeling

hiPSC-derived blood-brain barrier (BBB) models are valuable for pharmacological and physiological studies, yet their translational potential is limited due to insufficient cell phenotypes and the neglection of the complex environment of the BBB. This study evaluates the plasma compatibility with hiPSC-derived microvascular endothelial-like cells to enhance the translational potential of in vitro BBB models. Therefore, plasma samples (sodium/lithium heparin, citrate, EDTA) and serum from healthy donors were tested on hiPSC-derived microvascular endothelial-like cells at concentrations of 100%, 75%, and 50%. After 24 h, cell viability parameters were assessed. The impact of heparin-anticoagulated plasmas was further evaluated regarding barrier function and endothelial phenotype of differentiated endothelial-like cells. Finally, sodium-heparin plasma was tested in an isogenic triple-culture BBB model with continuous TEER measurements for 72 h. Only the application of heparin-anticoagulated plasmas did not significantly alter viability parameters compared to medium. Furthermore, heparin plasmas improved barrier function without increasing cell density and induced a von Willebrand factor signal. Finally, continuous TEER measurements of the triple-culture model confirmed the positive impact of sodium-heparin plasma on barrier function. Consequently, heparin-anticoagulated plasmas were proven to be compatible with hiPSC-derived microvascular endothelial-like cells. Thereby, the translational potential of BBB models can be substantially improved in the future.

Down-regulation of platelet-derived growth factor receptor β in pericytes increases blood-brain barrier permeability and significantly enhances α-synuclein in a Parkinson's Disease 3D cell model in vitro under hyperglycemic condition

BACKGROUND

Parkinson's Disease (PD) often presents with a compromised blood-brain barrier (BBB), which hyperglycemia may exacerbate. Pericytes, a key cell for BBB integrity, are potential therapeutic targets for neurodegenerative disorders. Few studies have developed 3D PD cell models incorporating neurovascular units (NVU) through the co-culture of human endothelial, pericytes, astrocytes, and SH-SY5Y cells to evaluate BBB impairment and the role of pericytes under hyperglycemic condition.

METHOD

A 3D PD like cell model was developed using 6-OHDA-affected SH-SY5Y cells, combined with endothelial cells, pericytes, and astrocytes through the Real Architecture for Tissue (RAFT) 3D co-culture system. PD incorporating reduced (30 % and 89 %) PDGFRβ NVU (RPN) with or without hyperglycemic model (HM) were also established. BBB permeability to sodium fluorescein was assessed, and BBB impairment was evaluated using BBB-associated proteins (ZO-1, CD54, CD144), cell-specific proteins (CD31, GFAP, PDGFRβ, CD13), tyrosine hydroxylase (TH), α-synuclein, oligomeric α-synuclein, and α-synuclein (ser9).

RESULTS

PD 3D cell models incorporating RPN with or without hyperglycemia were successfully established in vitro. Graduately increased BBB impairment was observed in PD, PD with RPN, and PD with RPN combined with HM, indicated by decreased BBB-associated and cell-specific proteins, reduced TH, and increased α-synuclein, oligomeric α-synuclein, and α-synuclein (ser9) compared to the NVU model.

CONCLUSION

Reduced pericyte PDGFRβ could increase BBB permeability, accelerate PD progression, and exacerbate under hyperglycemic condition.

Expression of alpha smooth muscle actin decreases with ageing and increases upon lumen obstruction in mouse brain pericytes

Cerebral pericytes are mural cells covering brain microvessels, organized as ensheathing, mesh and thin-strand pericytes. These latter two, together called capillary pericytes, have low levels of alpha smooth muscle actin (α-SMA), regulating basal vascular tone and applying a slow influence on cerebral blood flow. Pericytes are subject to alterations in ageing which may be even more pronounced in age-related pathologies, including microinfarcts, which usually affect a large number of vessels in the ageing brain. We modelled this condition by injecting 10 µm-size microspheres into the circulation of mice resulting in the occlusion of capillaries covered by ensheathing and mesh pericytes. We observed that α-SMA and Acta2, the gene encoding it, as well as TGF-β1/Tgfb1, the major regulator of α-SMA, decreased during ageing in cerebral microvessels. In the vicinity of the microspheres stalled in the capillaries, expression of α-SMA increased significantly in both ensheathing and especially in mesh pericytes, both in young (2 to 3 months of age) and old (24 months of age) mice. On the other hand, γ-actin was detected in endothelial cells, but not in pericytes, and decreased in microvessels of microsphere-containing hemispheres. Altogether, our data show that obstruction of cerebral microvessels increases α-SMA expression in pericytes in both age groups, but this does not compensate for the lower expression of the contractile protein in old animals. Increased α-SMA expression may lead to constriction of the obstructed vessels probably aggravating flow heterogeneity in the aged brain.

Skin calcium deposits in primary familial brain calcification: A novel potential biomarker

OBJECTIVE

Primary Familial Brain Calcification (PFBC) is a rare neurodegenerative disorder characterized by small vessel calcifications in the basal ganglia. PFBC is caused by pathogenic variants in different genes and its physiopathology is still largely unknown. Skin vascular calcifications have been detected in single PFBC cases, suggesting that calcium deposition may not be limited to the brain, but it is unknown whether this is a hallmark of all PFBC genetic and clinical subtypes. This work aims at assessing anatomical and subcellular localization of calcium-phosphate deposits in skin biopsies from PFBC patients to ascertain the accuracy of histological calcium staining in differentiating PFBC from healthy controls (HC) and Parkinson's Disease (PD).

METHODS

Histopathology and light microscopy of skin biopsy from 20 PFBC, 7 HC and 10 PD subjects (3 mm ø-5 mm deep punch biopsies, Hematoxylin-Eosin and vonKossa staining, immunoperoxidase CD31 staining); clinical, genetic and radiological assessment.

RESULTS

Unlike HC and PD subjects, the majority of PFBC patients (17/20) showed a consistent pattern of granular argyrophilic calcium-phosphate deposits in the basal lamina and the cytoplasm of CD31+ endothelial cells and pericytes of dermal capillaries, and the basement membrane of sweat glands. This pattern was unrelated to the underlying mutated gene or clinical status.

INTERPRETATION

Skin biopsy may be a novel PFBC diagnostic tool and a potential biomarker for future therapies, and a tool to investigate PFBC disease mechanisms. Different findings in some patients could be due to skin sampling variability and biological consequences of specific PFBC gene variants.

Cerebromicrovascular senescence in vascular cognitive impairment: does accelerated microvascular aging accompany atherosclerosis?

Vascular cognitive impairment (VCI) is a leading cause of age-related cognitive decline, driven by cerebrovascular dysfunction and cerebral small vessel disease (CSVD). Emerging evidence suggests that cerebromicrovascular endothelial senescence plays an important role in the pathogenesis of VCI by promoting cerebral blood flow dysregulation, neurovascular uncoupling, blood-brain barrier (BBB) disruption, and the development of cerebral microhemorrhages (CMHs). This review explores the concept of cerebromicrovascular senescence as a continuum of vascular aging, linking macrovascular atherosclerosis with microvascular dysfunction. It examines the mechanisms by which endothelial senescence drives neurovascular pathology and highlights the impact of cardiovascular risk factors in accelerating these processes. We examine preclinical and clinical studies that provide compelling evidence that atherosclerosis-induced microvascular senescence exacerbates cognitive impairment. In particular, findings suggest that targeting senescent endothelial cells through senolytic therapy can restore cerebrovascular function and improve cognitive outcomes in experimental models of atherosclerosis. Given the growing recognition of microvascular senescence as a therapeutic target, further research is warranted to explore novel interventions such as senolytics, anti-inflammatory agents, and metabolic modulators. The development of circulating biomarkers of vascular senescence (e.g., senescence-associated secretory phenotype [SASP] components and endothelial-derived extracellular vesicles) could enable early detection and risk stratification in individuals at high risk for VCI. Additionally, lifestyle modifications, including the Mediterranean diet, hold promise for delaying endothelial senescence and mitigating cognitive decline. In conclusion, cerebromicrovascular senescence is a key mechanistic link between atherosclerosis and cognitive impairment. Addressing microvascular aging as a modifiable risk factor through targeted interventions offers a promising strategy for reducing the burden of VCI and preserving cognitive function in aging populations.

Caveolae-Mediated Transcytosis and Its Role in Neurological Disorders

The blood-brain barrier (BBB) controls the flow of substances to maintain a homeostatic environment in the brain, which is highly regulated and crucial for the normal function of the central nervous system (CNS). Brain endothelial cells (bECs), which are directly exposed to blood, play the most important role in maintaining the integrity of the BBB. Unlike endothelial cells in other tissues, bECs have two unique features: specialized endothelial tight junctions and actively suppressed transcellular vesicle trafficking (transcytosis). These features help to maintain the relatively low permeability of the CNS barrier. In addition to the predominant role of tight junctions in the BBB, caveolae-mediated adsorptive transcytosis has attracted much interest in recent years. The active suppression of transcytosis is dynamically regulated during development and in response to diseases. Altered caveolae-mediated transcytosis of bECs has been reported in several neurological diseases, but the understanding of this process in bECs is limited. Here, we review the process of caveolae-mediated transcytosis based on previous studies and discuss its function in the breakdown of the BBB in neurological disorders.

A Soluble Epoxide Hydrolase Inhibitor Improves Cerebrovascular Dysfunction, Neuroinflammation, Amyloid Burden, and Cognitive Impairments in the hAPP/PS1 TgF344-AD Rat Model of Alzheimer's Disease

Alzheimer's disease (AD) is an increasing global healthcare crisis with few effective treatments. The accumulation of amyloid plaques and hyper-phosphorylated tau are thought to underlie the pathogenesis of AD. However, current studies have recognized a prominent role of cerebrovascular dysfunction in AD. We recently reported that SNPs in soluble epoxide hydrolase (sEH) are linked to AD in human genetic studies and that long-term administration of an sEH inhibitor attenuated cerebral vascular and cognitive dysfunction in a rat model of AD. However, the mechanisms linking changes in cerebral vascular function and neuroprotective actions of sEH inhibitors in AD remain to be determined. This study investigated the effects of administration of an sEH inhibitor, 1-(1-Propanoylpiperidin-4-yl)-3-[4-(trifluoromethoxy)phenyl]urea (TPPU), on neurovascular coupling, blood-brain barrier (BBB) function, neuroinflammation, and cognitive dysfunction in an hAPP/PS1 TgF344-AD rat model of AD. We observed predominant β-amyloid accumulation in the brains of 9-10-month-old AD rats and that TPPU treatment for three months reduced amyloid burden. The functional hyperemic response to whisker stimulation was attenuated in AD rats, and TPPU normalized the response. The sEH inhibitor, TPPU, mitigated capillary rarefaction, BBB leakage, and activation of astrocytes and microglia in AD rats. TPPU increased the expression of pre- and post-synaptic proteins and reduced loss of hippocampal neurons and cognitive impairments in the AD rats, which was confirmed in a transcriptome and GO analysis. These results suggest that sEH inhibitors could be a novel therapeutic strategy for AD.

A guide for blood-brain barrier models

Understanding the intricate mechanisms underlying brain-related diseases hinges on unraveling the pivotal role of the blood-brain barrier (BBB), an essential dynamic interface crucial for maintaining brain equilibrium. This review offers a comprehensive analysis of BBB physiology, delving into its cellular and molecular components while exploring a wide range of in vivo and in vitro BBB models. Notably, recent advancements in 3D cell culture techniques are explicitly discussed, as they have significantly improved the fidelity of BBB modeling by enabling the replication of physiologically relevant environments under flow conditions. Special attention is given to the cellular aspects of in vitro BBB models, alongside discussions on advances in stem cell technologies, providing valuable insights into generating robust cellular systems for BBB modeling. The diverse array of cell types used in BBB modeling, depending on their sources, is meticulously examined in this comprehensive review, scrutinizing their respective derivation protocols and implications. By synthesizing diverse approaches, this review sheds light on the improvements of BBB models to capture physiological conditions, aiding in understanding BBB interactions in health and disease conditions to foster clinical developments.

Brain pericytes and perivascular fibroblasts are stromal progenitors with dual functions in cerebrovascular regeneration after stroke

Functional revascularization is key to stroke recovery and requires remodeling and regeneration of blood vessels around which is located the brain's only stromal compartment. Stromal progenitor cells (SPCs) are critical for tissue regeneration following injury in many organs, yet their identity in the brain remains elusive. Here we show that the perivascular niche of brain SPCs includes pericytes, venular smooth muscle cells and perivascular fibroblasts that together help cerebral microvasculature regenerate following experimental stroke. Ischemic injury triggers amplification of pericytes and perivascular fibroblasts in the infarct region where they associate with endothelial cells inside a reactive astrocyte border. Fate-tracking of Hic1+ SPCs uncovered a transient functional and transcriptional phenotype of stroke-activated pericytes and perivascular fibroblasts. Both populations of these cells remained segregated, displaying distinct angiogenic and fibrogenic profiles. Therefore, pericytes and perivascular fibroblasts are distinct subpopulations of SPCs in the adult brain that coordinate revascularization and scar formation after injury.

Roles of PDGF/PDGFR signaling in various organs

Platelet-derived growth factors (PDGFs) ligands and their corresponding receptors, PDGF receptor (PDGFR)α and PDGFRβ, play a crucial role in controlling diverse biological functions, including cell growth, viability and migration. These growth factors bind to PDGFRs, which are receptor tyrosine kinases present on the surface of target cells. The interaction between PDGFs and PDGFRs induces receptor dimerization and subsequent activation through auto-phosphorylation, which in turn triggers a cascade of intracellular signaling pathways. PDGF/PDGFR signaling is essential for maintaining normal physiological functions, including tissue regeneration and growth. However, dysregulation of this signaling pathway leads to pathological conditions, including fibrosis, atherosclerosis, and cancer development in various organs. The pathological impact of PDGF/PDGFR signaling primarily stems from its capacity to promote excessive cell proliferation, enhanced migration, and increased extracellular matrix deposition, resulting in tissue overgrowth, scarring, and abnormal vessel formation. These processes are integral to the pathogenesis of fibrotic, neoplastic, and vascular disorders. Therefore, understanding these pathways is crucial for developing targeted treatments designed to inhibit PDGF/PDGFR signaling in these diseases. This review delves into the dual role of PDGF/PDGFR signaling in both physiological and pathophysiological contexts across different organs and provides insights into current pharmacological therapies designed to target the PDGF signaling pathway.

Longitudinal Investigation of Brain and Spinal Cord Pericytes After Inducible PDGFRβ+ Cell Ablation in Adult Mice

Central nervous system (CNS) pericytes play crucial roles in vascular development and blood-brain barrier maturation during prenatal development, as well as in regulating cerebral blood flow in adults. They have also been implicated in the pathogenesis of numerous neurological disorders. However, the behavior of pericytes in the adult brain after injury remains poorly understood, partly due to limitations in existing pericyte ablation models. To investigate pericyte responses following acute ablation and characterize a novel rodent model for pericyte research, we developed a tamoxifen-inducible PDGFRβ+ cell ablation model by crossing PDGFRβ-P2A-CreERT2 and Rosa26-DTA176 transgenic mouse lines. Using this model, we studied the effects of different tamoxifen doses and conducted histological examinations 15 and 60 days post-injection to assess the impacts of PDGFRβ+ cell ablation in both acute and chronic phases, respectively. Our results demonstrate that a low dose of tamoxifen effectively ablates PDGFRβ+ cells of the CNS in mice without reducing survival or causing significant systemic side effects, such as weight loss. Additionally, we found that the extent of PDGFRβ+ cell depletion varies between the cortex and the spinal cord, as well as between the gray and white matter regions of the spinal cord. Importantly, we observed that both pericyte coverage and numbers increased in the weeks following acute ablation, indicating the regenerative capacity of CNS pericytes in vivo. This study offers a valuable tool for future studies on the role of pericytes in neurological disorders by overcoming the limitations of constitutive pericyte ablation models and providing its longitudinal characterization in the CNS.

Fibrinogen degradation products exacerbate alpha-synuclein aggregation by inhibiting autophagy via downregulation of Beclin1 in multiple system atrophy

Multiple system atrophy (MSA) is a rapidly progressive neurodegenerative disease arising from accumulation of the α-synuclein and aberrant protein clearance in oligodendrocytes. The mechanisms of autophagy involved in the progression of MSA remain poorly understood. It is reported that MSA patients have blood-brain barrier impairments, which may increase the entry of fibrinogen into the brain. However, the roles of fibrinogen and its degradation products (FDPs) on autophagy and α-synuclein accumulation in MSA remain unknown. Here, we established the MSA animal model by intraperitoneal injection of 1-methyl-4-phenyl-1,2,3,6- tetrahydropyridine (MPTP) and 3-nitropropionic acid (3-NP), and cellular models by adding fibrillar α-syn into oligodendrocytes to investigate the mechanisms of FDPs on autophagy and accumulation of α-synuclein in oligodendrocytes. We found that FDPs inhibit the entry of α-synuclein into lysosomes for degradation, increasing aggregation of α-synuclein in oligodendrocytes (OLN-93). Our findings indicated that in OLN-93, FDPs inhibited the expressions of Beclin1 and Bif-1, which could promote the fusion of autophagosomes with lysosomes. Furthermore, the expression of α-synuclein was elevated in FDPs-injected mice, accompanied by an increase in the protein level of p62. We detected elevated expression of FDPs in the striatum of MSA mice. Finally, FDPs inhibited the expression of Beclin1 and Bif-1, which led to aberrant autophagic degradation and increased aggregation of α-synuclein and phospho-α-synuclein in MSA mice. Our study illustrates that FDPs can cause aggregation of α-synuclein in MSA by inhibiting Beclin1-mediated autophagy, which may exacerbate disease progression. These results provide a new therapeutic approach for MSA, that targets the inhibitory effect of FDPs on oligodendrocyte autophagy.

The blood-brain barriers: novel nanocarriers for central nervous system diseases

The central nervous system (CNS) diseases are major contributors to death and disability worldwide. However, the blood-brain barrier (BBB) often prevents drugs intended for CNS diseases from effectively crossing into the brain parenchyma to deliver their therapeutic effects. The blood-brain barrier is a semi-permeable barrier with high selectivity. The BBB primarily manages the transport of substances between the blood and the CNS. To enhance drug delivery for CNS disease treatment, various brain-based drug delivery strategies overcoming the BBB have been developed. Among them, nanoparticles (NPs) have been emphasized due to their multiple excellent properties. This review starts with an overview of the BBB's anatomical structure and physiological roles, and then explores the mechanisms, both endogenous and exogenous, that facilitate the NP passage across the BBB. The text also delves into how nanoparticles' shape, charge, size, and surface ligands affect their ability to cross the BBB and offers an overview of different nanoparticle classifications. This review concludes with an examination of the current challenges in utilizing nanomaterials for brain drug delivery and discusses corresponding directions for solutions. This review aims to propose innovative diagnostic and therapeutic approaches for CNS diseases and enhance drug design for more effective delivery across the BBB.

miRNA in blood-brain barrier repair: role of extracellular vesicles in stroke recovery

Ischemic stroke is a leading cause of mortality and long-term disability globally. One of its aspects is the breakdown of the blood-brain barrier (BBB). The disruption of BBB's integrity during stroke exacerbates neurological damage and hampers therapeutic intervention. Recent advances in regenerative medicine suggest that mesenchymal stem cells (MSCs) derived extracellular vesicles (EVs) show promise for restoring BBB integrity. This review explores the potential of MSC-derived EVs in mediating neuroprotective and reparative effects on the BBB after ischemic stroke. We highlight the molecular cargo of MSC-derived EVs, including miRNAs, and their role in enhancing angiogenesis, promoting the BBB and neural repair, and mitigating apoptosis. Furthermore, we discuss the challenges associated with the clinical translation of MSC-derived EV therapies and the possibilities of further enhancing EVs' innate protective qualities. Our findings underscore the need for further research to optimize the therapeutic potential of EVs and establish their efficacy and safety in clinical settings.

Screening and Identification of Brain Pericyte-Selective Markers

BACKGROUND

Pericytes, a type of mural cells, exert important functions in the CNS. One major challenge in pericyte research is the lack of pericyte-specific and subpopulation-specific markers.

METHODS

To address this knowledge gap, we first generated a novel transgenic mouse line in which vascular smooth muscle cells (vSMCs) are permanently labeled with tdTomato. Next, we isolated PDGFRβ+tdTomato- pericytes and PDGFRβ+tdTomato+ vSMCs from the brains of these mice and subsequently performed RNAseq analysis to identify pericyte-enriched genes.

RESULTS

Using this approach, we successfully identified 40 pericyte-enriched genes and 158 vSMC-enriched genes, which are involved in different biological processes and molecular functions. Using ISH/IHC analysis, we found that Pla1a and Cox4i2 were predominantly enriched in subpopulations of brain pericytes, although they also marked some non-vascular parenchymal cells.

CONCLUSIONS

These findings suggest that Pla1a and Cox4i2 preferably label subpopulations of pericytes in the brain compared to vSMCs, and thus, they may be useful in distinguishing these populations.

Aging disrupts blood-brain and blood-spinal cord barrier homeostasis, but does not increase paracellular permeability

Blood-CNS barriers protect the CNS from circulating immune cells and damaging molecules. It is thought barrier integrity becomes disrupted with aging, contributing to impaired CNS function. Using genome-wide and targeted molecular approaches, we found aging affected expression of predominantly immune invasion and pericyte-related genes in CNS regions investigated, especially after middle age, with spinal cord being most impacted. We did not find significant perturbation of endothelial cell junction genes or proteins, nor were vascular density or pericyte coverage affected by aging. We evaluated barrier paracellular permeability using small molecular weight tracers, serum protein extravasation, CNS water content, and iron labelling measures. We found no evidence for age-related increased barrier permeability in any of these tests. We conclude that blood-brain (BBB) and blood-spinal cord barrier (BSCB) paracellular permeability does not increase with normal aging in mouse. Whilst expression changes were not associated with increased permeability, they may represent an age-related primed state whereby additional insults cause increased leakiness.

Cell-specific transcriptional signatures of vascular cells in Alzheimer's disease: perspectives, pathways, and therapeutic directions

Alzheimer's disease (AD) is a debilitating neurodegenerative disease that is marked by profound neurovascular dysfunction and significant cell-specific alterations in the brain vasculature. Recent advances in high throughput single-cell transcriptomics technology have enabled the study of the human brain vasculature at an unprecedented depth. Additionally, the understudied niche of cerebrovascular cells, such as endothelial and mural cells, and their subtypes have been scrutinized for understanding cellular and transcriptional heterogeneity in AD. Here, we provide an overview of rich transcriptional signatures derived from recent single-cell and single-nucleus transcriptomic studies of human brain vascular cells and their implications for targeted therapy for AD. We conducted an in-depth literature search using Medline and Covidence to identify pertinent AD studies that utilized single-cell technologies in human post-mortem brain tissue by focusing on understanding the transcriptional differences in cerebrovascular cell types and subtypes in AD and cognitively normal older adults. We also discuss impaired cellular crosstalk between vascular cells and neuroglial units, as well as astrocytes in AD. Additionally, we contextualize the findings from single-cell studies of distinct endothelial cells, smooth muscle cells, fibroblasts, and pericytes in the human AD brain and highlight pathways for potential therapeutic interventions as a concerted multi-omic effort with spatial transcriptomics technology, neuroimaging, and neuropathology. Overall, we provide a detailed account of the vascular cell-specific transcriptional signatures in AD and their crucial cellular crosstalk with the neuroglial unit.

Intracerebral Hemorrhage-Associated Iron Release Leads to Pericyte-Dependent Cerebral Capillary Function Disruption

Intracerebral hemorrhage leads to immediate brain injury due to local mechanical damage, on which current treatment approaches are focused, but it also induces secondary brain injury. The purpose of this study is to characterize blood components, degradation products and their effects in secondary brain injury. Immunocyto- and immunohistochemistry, Fluorescence-Activated Cell Sorting, WST-1 assays and RNA sequencing were applied using human cell cultures and human ex vivo brain tissue slices. Brain tissue was immediately collected, cooled and sliced during neurosurgical operations to perform experiments on living tissue slices of the human brain. Among the blood degradation products, free iron (Fe2+ and Fe3+), but not hemoglobin, induced detrimental effects on pericyte function and survival (78.5% vs. 94.3%; p-value < 0.001). RNA sequencing revealed ferroptosis as the underlining cellular mechanism, mediated via GPX-4 (log2 fold change > 1.0, p-value < 1.08 × 10-30) in pathway analysis and eventually resulting in oxidative cell death. Pericytes located at cerebral capillary branching sites were specifically affected by ferroptosis, leading to capillary disruption and vasoconstriction, which were partially prevented by ferrostatin-1. Free iron induces the pericyte-dependent disruption of cerebral capillary function and represents a therapeutic target to attenuate secondary injury after intracerebral hemorrhage.

Blood-Brain Barrier Disruption in Schizophrenia: Insights, Mechanisms, and Future Directions

The blood-brain barrier (BBB) plays a crucial role in maintaining the homeostasis of the central nervous system by regulating solute transport and preventing neurotoxic substances from infiltrating brain tissue. In schizophrenia, emerging evidence identifies BBB dysfunction as a key pathophysiological factor associated with neuroinflammation, tight junction abnormalities, and endothelial dysfunction. Recent advancements in neuroimaging techniques, such as arterial spin labeling (ASL), have provided valuable tools for investigating BBB permeability and its role in disease progression. This review synthesizes findings from postmortem studies, serum and cerebrospinal fluid biomarker analyses, and advanced neuroimaging research to elucidate BBB alterations in schizophrenia. It highlights the mechanistic roles of tight junction protein dysregulation, neurovascular unit dysfunction, and immune responses in disrupting BBB integrity. Furthermore, the review examines the bidirectional effects of antipsychotic medications on BBB, addressing both therapeutic opportunities and potential challenges. By emphasizing the pivotal role of BBB dysfunction in schizophrenia pathogenesis, this review underscores its translational potential. Through the integration of multidisciplinary evidence, it lays the foundation for innovative diagnostic approaches and therapeutic strategies, enhancing our understanding of schizophrenia's complex pathophysiology.

The Rise of Pluripotent Stem Cell-Derived Glia Models of Neuroinflammation

Neuroinflammation is a blanket term that describes the body's complex inflammatory response in the central nervous system (CNS). It encompasses a phenotype shift to a proinflammatory state, the release of cytokines, the recruitment of peripheral immune cells, and a wide variety of other processes. Neuroinflammation has been implicated in nearly every major CNS disease ranging from Alzheimer's disease to brain cancer. Understanding and modeling neuroinflammation is critical for the identification of novel therapeutic targets in the treatment of CNS diseases. Unfortunately, the translation of findings from non-human models has left much to be desired. This review systematically discusses the role of human pluripotent stem cell (hPSC)-derived glia and supporting cells within the CNS, including astrocytes, microglia, oligodendrocyte precursor cells, pericytes, and endothelial cells, to describe the state of the field and hope for future discoveries. hPSC-derived cells offer an expanded potential to study the pathobiology of neuroinflammation and immunomodulatory cascades that impact disease progression. While much progress has been made in the development of models, there is much left to explore in the application of these models to understand the complex inflammatory response in the CNS.

Device-assisted strategies for drug delivery across the blood-brain barrier to treat glioblastoma

The blood-brain barrier, essential for protecting the central nervous system, also restricts drug delivery to this region. Thus, delivering drugs across the blood-brain barrier is an active research area in immunology, oncology, and neurology; moreover, novel methods are urgently needed to expand therapeutic options for central nervous system pathologies. While previous strategies have focused on small molecules that modulate blood-brain barrier permeability or penetrate the barrier, there is an increased focus on biomedical devices-external or implanted-for improving drug delivery. Here, we review device-assisted drug delivery across the blood-brain barrier, emphasizing its application in glioblastoma, an aggressively malignant primary brain cancer in which the blood-brain barrier plays a central role. We examine the blood-brain barrier and its features in glioblastoma, emerging models for studying the blood-brain barrier, and device-assisted methods for crossing the blood-brain barrier. We conclude by presenting methods to monitor the blood-brain barrier and paradigms for combined cross-BBB drug delivery.

The Contribution of the Renin-Angiotensin System to Alzheimer's Disease

The renin-angiotensin system (RAS) is becoming increasingly recognised as a biochemical pathway relevant to the development and progression of Alzheimer's disease (AD). RAS involvement in AD was initially linked to AD via numerous genetic association studies and more recent Genome-Wide Association Studies (GWAS), and in some cases in relation to classical hallmarks of AD pathology. Since these initial findings, which will be summarised here, several complementary areas of research are converging in support of what has been proposed as the Angiotensin Hypothesis for Alzheimer's disease. This hypothesis proposes how the RAS and disease-associated changes to the normal balance between opposing regulatory pathways within RAS warrant careful consideration in the pathogenesis of AD and its pathology. We discuss some of these in relation to RAS-targeting therapeutics, originally developed for the treatment of cardiovascular conditions, and how they might be repurposed as interventions for AD.

Fish microglia: Beyond the resident macrophages of the central nervous system - A review of their morphofunctional characteristics

From classical to modern literature on microglia, the importance of the potential and variability of these immune cells in vertebrates has been pointed out. Recent aspects such as relationships and interactions between microglia and neurons in both normal and injured neural tissues, as well as their nexus with other organs and with the microbiota, or how these cells are modulated during development and adulthood are current topics of major interest. State-of-the-art research methodologies, including microscopy and potent in vivo imaging techniques, genomic and proteomic methods, current culture conditions together with the easy maintenance and manipulation of some fish embryos and adult specimens such as zebrafish (Danio rerio), have emerged and adapted to the phylogenetic position of some fish species. Furthermore, these advancements have facilitated the development of successful protocols aimed at addressing significant hypotheses and unresolved questions regarding vertebrate glia. The present review aims to analyse the available information on fish microglia, mainly the most recent one concerning teleosts, to establish an overview of their structural and immune functional features as a basis for their potentialities, heterogeneity, diversification, involvement, and relationships with neurons under normal and pathological conditions.

From BBB to PPP: Bioenergetic requirements and challenges for oligodendrocytes in health and disease

Mature myelinating oligodendrocytes, the cells that produce the myelin sheath that insulates axons in the central nervous system, have distinct energetic and metabolic requirements compared to neurons. Neurons require substantial energy to execute action potentials, while the energy needs of oligodendrocytes are directed toward building the lipid-rich components of myelin and supporting neuronal metabolism by transferring glycolytic products to axons as additional fuel. The utilization of energy metabolites in the brain parenchyma is tightly regulated to meet the needs of different cell types. Disruption of the supply of metabolites can lead to stress and oligodendrocyte injury, contributing to various neurological disorders, including some demyelinating diseases. Understanding the physiological properties, structures, and mechanisms involved in oligodendrocyte energy metabolism, as well as the relationship between oligodendrocytes and neighboring cells, is crucial to investigate the underlying pathophysiology caused by metabolic impairment in these disorders. In this review, we describe the particular physiological properties of oligodendrocyte energy metabolism and the response of oligodendrocytes to metabolic stress. We delineate the relationship between oligodendrocytes and other cells in the context of the neurovascular unit, and the regulation of metabolite supply according to energetic needs. We focus on the specific bioenergetic requirements of oligodendrocytes and address the disruption of metabolic energy in demyelinating diseases. We encourage further studies to increase understanding of the significance of metabolic stress on oligodendrocyte injury, to support the development of novel therapeutic approaches for the treatment of demyelinating diseases.

3D Neurovascular Unit Tissue Model to Assess Responses to Traumatic Brain Injury

The neurovascular unit (NVU) is a critical interface in the central nervous system that links vascular interactions with glial and neural tissue. Disruption of the NVU has been linked to the onset and progression of neurodegenerative diseases. Despite its significance the NVU remains challenging to study in a physiologically relevant manner. Here, a 3D cell triculture model of the NVU is developed that incorporates human primary brain microvascular endothelial cells, astrocytes, and pericytes into a tissue system that can be sustained in vitro for several weeks. This tissue model helps recapitulate the complexity of the NVU and can be used to interrogate the mechanisms of disease and cell-cell interactions. The NVU tissue model displays elevated cell death and inflammatory responses following mechanical damage, to emulate traumatic brain injury (TBI) under controlled laboratory conditions, including lactate dehydrogenase (LDH) release, elevated inflammatory markers TNF-α and monocyte chemoattractant cytokines MCP-2 and MCP-3 and reduced expression of the tight junction marker ZO-1. This 3D tissue model serves as a tool for deciphering mechanisms of TBIs and immune responses associated with the NVU.

Physiological Insights Into the Role of Pericytes in Spinal Cord Injury

Vascular regeneration plays a vital role in tissue repair yet is drastically impaired in those with a spinal cord injury (SCI). Pericytes are of great significance as they are entwined with vessel-specific endothelial cells and actively contribute to maintaining the spinal cord's vascular network. Within the neurovascular unit (NVU), subtypes of pericytes characterized by various markers such as PDGFR-β, Desmin, CD146, and NG-2 are involved in vascular regeneration in SCI repair. Various pericyte signaling, pericyte-derived exosomes, and endothelial-pericyte interplay were revealed to participate in SCI repair or fibrotic scars. Through further understanding pericyte biology, it is aimed to accurately generate subtypes of pericytes and develop their therapeutic potential. This review focuses on recent advanced research and development of pericytes as a potential treatment for SCI.

Accelerated biological aging increases the risk of short- and long-term stroke prognosis in patients with ischemic stroke or TIA

BACKGROUND

Biological age (BA), an integrated measure of physiological aging, has a clear link to stroke. There is a paucity of long-term longitudinal studies about the association between accelerated biological age and stroke prognosis in patients with previous strokes, and the differences in the predictive ability of various BA indicators calculated from clinical biochemistry biomarkers for future stroke outcomes are still unknown. To evaluate the role of three accelerated BA indicators for short- and long-term prognosis of patients with ischemic stroke or transient ischemic attack (TIA), and to identify the most appropriate predictor.

METHODS

This study included 7396 patients from the Third China National Stroke Registry (CNSR-III), a prospective national registry of patients with acute ischemic stroke or TIA between August 2015 and March 2018 in China. We constructed accelerated BA using three widely recognized algorithms: PhenoAge, Klemera-Doubal, and HD method. To ascertain the association of accelerated BA with the risk of short- and long-term stroke outcomes, a Cox or logistic regression model was conducted for the analysis. The net reclassification index and integrated discrimination improvement were used to evaluate the added model improvement ability of BA acceleration.

FINDINGS

Compared to those with the lowest of PhenoAge acceleration, patients with the highest were more likely to have a higher risk of stroke (HR 1.98, 95% CI 1.49-2.63, P < 0.001), ischemic stroke (HR 1.88, 95% CI 1.41-2.53, P < 0.001), composite vascular events (HR 2.03, 95% CI 1.53-2.68, P < 0.001), all-cause death (HR 7.02, 95% CI 3.41-14.47, P < 0.001) and the modified Rankin scale of 3-6 (OR 2.55, 95% CI 2.05-3.16, P < 0.001) at three months, and the association observed within one year and five years was similar to that within three months. The risk of all stroke outcomes for HDAge was consistent with PhenoAge acceleration, but KDMAge acceleration was the same, except for stroke within one year (HR 1.24, 95% CI 1.00-1.53, P = 0.053). PhenoAge acceleration provided a better improvement in the model's predictive ability for stroke prognosis, compared to BA determined by other algorithms.

INTERPRETATION

In this prospective cohort study, BA acceleration, particularly PhenoAge, may help identify stroke patients with risks of short- and long-term poor outcomes, potentially enabling subclinical prevention and early intervention.

FUNDING

This work was supported by grants from Chinese Academy of Medical Sciences Innovation Fund for Medical Sciences (2019-I2M-5-029), the National Natural Science Foundation of China (U20A20358), Beijing Hospitals Authority Clinical Medicine Development of special funding support (ZLRK202312), the National Key R&D Program of China (No. 2022YFC3602500, 2022YFC3602505), Outstanding Young Talents Project of Capital Medical University (A2105), and Beijing High-Level Public Health Technical Personnel Construction Project (Discipline leader -03-12).

Pericyte ablation causes hypoactivity and reactive gliosis in adult mice

Capillary pericytes are important regulators of cerebral blood flow, blood-brain barrier integrity and neuroinflammation, but can become lost or dysfunctional in disease. The consequences of pericyte loss or dysfunction is extremely difficult to discern when it forms one component of a complex disease process. To evaluate this directly, we examined the effect of adult pericyte loss on mouse voluntary movement and motor function, and physiological responses such as hypoxia, blood-brain barrier (BBB) integrity and glial reactivity. Tamoxifen delivery to Pdgfrβ-CreERT2:: Rosa26-DTA transgenic mice was titrated to produce a dose-dependent ablation of pericytes in vivo. 100mg/kg of tamoxifen ablated approximately half of all brain pericytes, while two consecutive daily doses of 300mg/kg tamoxifen ablated >80% of brain pericytes. In the open field test, mice with ∼50% pericyte loss spent more time immobile and travelled half the distance of control mice. Mice with >80% pericyte ablation also slipped more frequently while performing the beam walk task. Our histopathological analyses of the brain revealed that blood vessel density was unchanged, but vessel lumen width was increased. Pericyte-ablated mice also exhibited: mild BBB disruption; increased neuronal hypoxia; astrogliosis and increased IBA1+ immunoreactivity, suggestive of microgliosis and/or macrophage infiltration. Our results highlight the importance of pericytes in the brain, as pericyte loss can directly compromise brain health and induce behavioural alterations in mice.

SS-OCTA assessment of fundus microvascular changes and their correlation with coronary lesion severity in severe coronary heart disease

This study aimed to quantify fundus microvascular alterations in patients requiring revascularization for coronary heart disease (CHD) using swept-source optical coherence tomography angiography (SS-OCTA) and to investigate the correlation between these alterations and the severity of coronary artery lesions. SS-OCTA was employed to assess the fundus neurovascular parameters of all participants, while the Gensini score was utilized to gauge the severity of coronary artery lesions in observation group. A total of 98 participants (49 CHD patients and 49 controls) were included. Analysis of the SS-OCTA parameters revealed that the vascular density (VD) of the superficial vascular plexus (SVP), the superficial vascular complex (SVC), the intermediate capillary plexus (ICP) in the parafoveal region, the mean ICP in the macula, deep capillary plexus (DCP) and deep vascular complex (DVC) in each macular region were significantly reduced in the observation group compared to the control group (P < 0.05). Multivariate logistic regression indicated that lower VD values in the SVP, SVC, ICP, DCP and DVC across macular regions were significantly associated with an increased likelihood of severe CHD (OR < 1, P < 0.05). ROC curve analysis revealed that the maximum area under the curve for overall DCP VD in the macula was 0.707, with a cutoff value of 19.64, sensitivity of 65.30%, and specificity of 73.50%. In CHD group, Pearson correlation analysis demonstrated a negative correlation between the Gensini score and mean DCP VD (r = - 0.491, P < 0.001). Retinal VD in patients requiring revascularization for CHD is significantly lower compared to healthy controls. SS-OCTA-based retinal microvascular damage assessment is a valuable tool for risk stratification and early intervention in CHD.

Mesenchymal Stem Cells and Their Extracellular Vesicles: Therapeutic Mechanisms for Blood-Spinal Cord Barrier Repair Following Spinal Cord Injury

Spinal cord injury (SCI) disrupts the blood-spinal cord barrier (BSCB) exacerbating damage by allowing harmful substances and immune cells to infiltrate spinal neural tissues from the vasculature. This leads to inflammation, oxidative stress, and impaired axonal regeneration. The BSCB, essential for maintaining spinal cord homeostasis, is structurally similar to the blood-brain barrier. Its restoration is a key therapeutic target for improving outcomes in SCI. Mesenchymal stromal/stem cells (MSCs) and their secreted extracellular vesicles (MSC-EVs) have gained attention for their regenerative, immunomodulatory, and anti-inflammatory properties in promoting BSCB repair. MSCs enhance BSCB integrity by improving endothelial-pericyte association, restoring tight junction proteins, and reducing inflammation. MSC-EVs, which deliver bioactive molecules, replicate many of MSCs' therapeutic effects, and offer a promising cell-free alternative. Preclinical studies have shown that both MSCs and MSC-EVs can reduce BSCB permeability, promote vascular stability, and support functional recovery. While MSC therapy is advancing in clinical trials, MSC-EV therapies require further optimization in terms of production, dosing, and delivery protocols. Despite these challenges, both therapeutic approaches represent significant potential for treating SCI by targeting BSCB repair and improving patient outcomes.

Defective autophagy of pericytes enhances radiation-induced senescence promoting radiation brain injury

BACKGROUND

Radiation-induced brain injury (RBI) represents a major challenge for cancer patients undergoing cranial radiotherapy. However, the molecular mechanisms and therapeutic strategies of RBI remain inconclusive. With the continuous exploration of the mechanisms of RBI, an increasing number of studies have implicated cerebrovascular dysfunction as a key factor in RBI-related cognitive impairment. As pericytes are a component of the neurovascular unit, there is still a lack of understanding in current research about the specific role and function of pericytes in RBI.

METHODS

We constructed a mouse model of RBI-associated cognitive dysfunction in vivo and an in vitro radiation-induced pericyte model to explore the effects of senescent pericytes on the blood-brain barrier (BBB) and normal central nervous system cells, even glioma cells. To further clarify the effects of pericyte autophagy on senescence, molecular mechanisms were explored at the animal and cellular levels. Finally, we validated the clearance of pericyte senescence by using a senolytic drug and all-trans retinoic acid to investigate the role of radiation-induced pericyte senescence.

RESULTS

Our findings indicated that radiation-induced pericyte senescence plays a key role in BBB dysfunction, leading to RBI and subsequent cognitive decline. Strikingly, pericyte senescence also contributed to the growth and invasion of glioma cells. We further demonstrated that defective autophagy in pericytes is a vital regulatory mechanism for pericyte senescence. Moreover, autophagy activated by rapamycin could reverse pericyte senescence. Notably, the elimination of senescent cells by senolytic drugs significantly mitigated radiation-induced cognitive dysfunction.

CONCLUSIONS

Our results demonstrated that pericyte senescence may be a promising therapeutic target for RBI and glioma progression.