Pericytes: developmental, physiological, and pathological perspectives, problems, and promises

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).

Advances in brain-targeted delivery strategies and natural product-mediated enhancement of blood-brain barrier permeability

The blood-brain barrier (BBB) represents a formidable challenge in the treatment of neurological disorders, as it restricts the passage of most therapeutic agents into the central nervous system (CNS). Research in brain-targeted delivery strategies and explore in natural products for BBB modulation have opened new avenues for effective CNS drug delivery. This review highlights the latest developments in molecular-based delivery systems, cell-based approaches, physical techniques, toxicity concerns, clinical trials and artificial intelligence (AI) -driven modeling for brain-targeted drug delivery. Additionally, it examines the role of natural products, particularly aromatic resuscitation medicines, in enhancing BBB permeability through modulating tight junction proteins and inhibiting efflux transporters. It is emphasized that the integration of natural products with modern drug delivery systems offers promising opportunities for the development of novel brain-targeted therapies. However, challenges related to the complexity and variety of natural product compositions must be addressed to fully realize their potential. This review underscores the importance of continued research into the molecular mechanisms underlying BBB modulation and natural product-mediated nano-delivery strategies for CNS disorders.

Two waves of adipogenesis in developing avian skin and dermal plasticity

How the complex architecture of skin is constructed, balancing both similarity and adaptive diversity, is not well understood. We propose that the developmental assembly of skin components, including skin appendages, dermal muscles, dermal adipose tissues, and vasculature, is interdependent and adaptive, enabling different species to adjust to their respective environments. Using the developing chicken skin model, we recently demonstrated that the intradermal muscle network and vasculature are organized with feather buds as reference points during the process of adaptive tissue patterning. In this study, we investigate the development of adipose tissue in the avian skin and compare them in different avian species (chicken, quail, duck). Avian skin contains two types of adipose tissue: subcutaneous white adipose tissue (SWAT) is skin associate adipose tissue located in subcutaneous layer, while dermal white adipose tissue (DWAT) consists of a layer of adipocytes within the dermis. Using elastin to distinguish dermal and subcutaneous layers, we observed two distinct waves of adipogenesis, shown by Oil Red O staining. The first wave, representing SWAT, begins around chicken embryonic day 14 (E14) from the posterior dorsal region. These adipocyte clusters are aligned with vasculatures. The second wave, representing DWAT, starts around E16, from the body midline where feather buds are more mature and starts to form smooth muscle network. DWAT adipocytes appear around feather follicles and align with the intradermal smooth muscle network, forming a grid pattern. The association between DWAT and dermal muscle was further explored. Some SMA-positive cells show co-expression of early adipocyte markers, suggesting a shared lineage. Lineage tracing using SMA-Cre revealed that some SMA+ cells in developing skin can give rise to adipocytes, shown by co-staining with the C/EBPα antibody. To explore differences of adipose tissues in birds living in different environments, we examined aquatic bird duck. In the duck, the first wave of SWAT appears in embryonic development from both scapular and femoral regions, while the second wave of DWAT also starts from the midline, surrounding feather follicles. Both waves are significantly more abundant in ducks, reflecting the adaptation in the duck skin. These findings suggest developmental relationships among tissue components in the skin-such as feathers, fat, vasculature, and dermal smooth muscle-are interconnected and adaptive, setting up the foundation for further investigation on regulatory mechanisms of dermal plasticity.

Breaking the fortress: a mechanistic review of meningitis-causing bacteria breaching tactics in blood brain barrier

The blood-brain barrier is a physiological protective barrier around blood vessels in the brain. It prevents most bacteria and harmful substances from entering the brain through the blood. However, when bacterial meningitis occurs, bacteria enter the brain either from the circulation or by direct invasion from neighbouring structures, causing an inflammatory response that in severe cases may lead to death. High morbidity and mortality are prominent features of the disease. Many pathogenic bacteria can break through the blood-brain barrier and cause meningitis, such as Streptococcus pneumoniae, Group B Streptococcus, Streptococcus suis, Neisseria meningitidis, meningitis-associated Escherichia coli, etc. This article reviews the mechanisms by which these bacteria cross the blood-brain barrier when causing meningitis and the interactions between bacteria and host cells to help pathogens invade the brain. Clarifying the mechanism by which pathogens cross the blood-brain barrier can provide new ideas for developing effective treatments for bacterial meningitis.

Pericytes in hematogenous metastasis: mechanistic insights and therapeutic approaches

Metastasis, the leading cause of cancer-related deaths, underscores the critical need to understand its regulatory mechanisms to improve prevention and treatment strategies for late-stage tumors. Hematogenous dissemination is a key route of metastasis. However, as the gatekeeper of vessels, the role of pericytes in hematogenous metastasis remains largely unknown. In this review, we comprehensively explore the contributions of pericytes throughout the metastatic cascade, particularly their functions that extend beyond influencing tumor angiogenesis. Pericytes should not be perceived as passive bystanders, but rather as active participants in various stages of the metastatic cascade. Pericytes-targeted therapy may provide novel insights for preventing and treating advanced-stage tumor.

Endothelia-targeting eye drops deliver a STING inhibitor to effectively reduce retinal neovascularization in ischemic retinopathy

Retinal neovascularization is the main pathologic feature of ischemic retinopathy, which eventually leads to vision loss and even blindness. Current treatments like laser photocoagulation and intravitreal injection of anti-vascular endothelial growth factor A drugs are invasive, expensive, and incompetent. Therefore, it is urgent to explore optimized therapies, particularly eye drops, to improve treatment effects. Our recent study reported that abnormal up-regulation of stimulator of interferon genes (STING) is closely associated with retinal vascular diseases, and it is highly enriched in retinal endothelial cells with retinopathy. Thus, we evaluated whether endothelial STING affects retinal neovascularization. In addition, we constructed iRGD- and TAT-decorated nanoparticles (NPs) loaded with C-176 (I/T-C-NP), capable of penetrating the cornea and targeting retinal endothelial cells. The I/T-C-NP eye drops were applied to the eyes of oxygen-induced retinopathy mice, resulting in attenuated activation of the STING pathway. Consequently, retinal neovascularization and vascular tortuosity were effectively reduced, astrocyte activation was prohibited, and pericyte coverage was improved. These observations suggest that I/T-C-NP eye drops can be a potential solution for the treatment of retinal neovascularization.

Pdgfrβ marks distinct mesenchymal and pericyte populations within the periosteum with overlapping cellular features

Platelet-derived growth factor receptor β (Pdgfrβ) is a cell surface marker often present on mesenchymal progenitor cells, playing a key role in regulating cell proliferation, migration, and survival. In the skeleton, Pdgfrβ-positive cells have significant osteogenic potential, differentiating into osteoblasts after injury to promote bone repair and homeostasis. However, multiple cell types within bone tissue express Pdgfrβ and their overlapping or distinct cellular features remain incompletely understood. Using a combination of single-cell RNA sequencing and transgenic Pdgfrβ-CreERT2-mT/mG reporter mice, we examined Pdgfrβ+ cells in mouse long bone periosteum. By single-cell analysis, Pdgfrb expression was found among a subset of mesenchymal cells and universally among pericytes within the periosteum. Histologic analysis of Pdgfrβ reporter activity confirmed a combination of perivascular and non-perivascular Pdgfrβ-expressing cell types. When isolated, Pdgfrβ reporter+ skeletal periosteal cells showed enhanced colony-forming, proliferative, migratory, and osteogenic capacities. Pdgfrβ reporter+ cells were further distinguished by co-expression of the pericyte marker CD146, which yielded Pdgfrβ+CD146+ pericytes and Pdgfrβ+CD146- skeletal mesenchymal cells. Colony forming and proliferative capacity were most highly enriched among Pdgfrβ+CD146+ pericytes, while osteogenic differentiation was similarly enriched across both Pdgfrβ+ cell fractions. In summary, Pdgfrβ expression identifies multiple subsets of progenitor cells within long bone periosteum with or without perivascular distribution and with overlapping cellular features.

The Discovery of the Pericytes: A Historical Note

Pericytes are adventitial cells located within the basement membranes of capillaries and post-capillary venules. Because they have multiple cytoplasmic processes and distinctive cytoskeletal elements, and envelope endothelial cells, pericytes are considered cells that stabilize the vessel wall, controlling endothelial cell proliferation and thereby the growth of new capillaries. Several molecules are involved in controlling and modulating the interactions between pericytes and endothelial cells, such as platelet-derived growth factor beta (PDGFβ), transforming growth factor beta (TGFβ), and angiopoietins (Angs).

A spatiotemporal and machine-learning platform facilitates the manufacturing of hPSC-derived esophageal mucosa

Human pluripotent stem cell-derived tissue engineering offers great promise for designer cell-based personalized therapeutics, but harnessing such potential requires a deeper understanding of tissue-level interactions. We previously developed a cell replacement manufacturing method for ectoderm-derived skin epithelium. However, it remains challenging to manufacture the endoderm-derived esophageal epithelium despite possessing a similar stratified epithelial structure. Here, we employ single-cell and spatial technologies to generate a spatiotemporal multi-omics cell census for human esophageal development. We identify the cellular diversity, dynamics, and signal communications for the developing esophageal epithelium and stroma. Using Manatee, a machine-learning algorithm, we prioritize the combinations of candidate human developmental signals for in vitro derivation of esophageal basal cells. Functional validation of Manatee predictions leads to a clinically compatible system for manufacturing human esophageal mucosa.

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.

Fibroblastic reticular cells form reactive myeloid cell niches in human lymph nodes

Lymph nodes play a key role in maintaining fluid balance in homeostatic and inflamed tissues and provide fibroblastic niche environments for optimal immune cell positioning and interaction. Here, we used single-cell and spatial transcriptomic analyses in combination with high-resolution imaging to molecularly define and functionally characterize niche-forming cells that control inflammation-driven remodeling in human lymph nodes. Fibroblastic reticular cells responded to inflammatory perturbation with activation and expansion of poised niche environments. Inflammation-induced adaptation of lymph node infrastructure and topography included the expansion of peptidase inhibitor 16 (PI16)-expressing reticular cell (PI16+ RC) networks that enwrap the perivenular conduit system. Interactome analyses indicated that macrophage-derived oncostatin M directs PI16+ RC activation in inflamed lymph nodes and thereby promotes immune cell aggregation in the perivenular space. In conclusion, these data demonstrate that the inflammatory remodeling of human lymph nodes results in the formation of reactive myeloid cell niches by PI16+ RCs.

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.

Circulating exosomes in pediatric obstructive sleep apnea with or without neurocognitive deficits and their effects on a 3D-blood-brain barrier spheroid model

Obstructive sleep apnea (OSA) in children is linked to cognitive impairments, potentially due to blood-brain barrier (BBB) dysfunction. Exosomes, small vesicles released by most cells, reflect cellular changes. This study examined the effects of exosomes from children with OSA, with or without cognitive deficits, on neurovascular unit (NVU) models. Twenty-six children were categorized into three groups: healthy controls (Cont, n = 6), OSA without cognitive deficits (OSA-NG, n = 10), and OSA with neurocognitive deficits (OSA-POS, n = 10). Plasma exosomes were characterized and applied to human 3D NVU spheroids for 24 h. Barrier integrity, permeability, and angiogenesis were assessed using trans-endothelial electrical resistance (TEER), tight junction integrity, and tube formation assays. Single-nucleus RNA sequencing (snRNA-seq) and bioinformatics, including CellChat analysis, identified intercellular signaling pathways. Results showed that exosomes from OSA-POS children disrupted TEER, increased permeability, and impaired ZO1 staining in spheroids, compared to the other groups. Both OSA-POS and OSA-NG exosomes increased permeability in NVU cells in monolayer and microfluidic BBB models. snRNA-seq analysis further revealed distinct cell clusters and pathways associated with the different groups. This 3D NVU spheroid model provides a robust platform to study BBB properties and the role of exosomes in OSA. These findings suggest that integrating snRNA-seq with exosome studies can uncover mechanisms underlying neurocognitive dysfunction in pediatric OSA, potentially leading to personalized therapeutic approaches.

Laminins and the blood-brain barrier

The blood-brain barrier (BBB) is a dynamic structure that maintains brain homeostasis. BBB breakdown is a key pathological hallmark of almost all neurological diseases. Although the regulation of BBB integrity by different cells has been extensively studied, the function of its non-cellular component-the basal lamina in BBB regulation remains largely unknown. Laminin, a trimeric protein with multiple isoforms, is one of the most important constituents of the basal lamina. In the CNS, different cells synthesize distinct laminin isoforms, which differentially regulate BBB integrity in both physiological and pathological conditions. A thorough understanding of laminin expression and function in BBB integrity could lead to the identification of novel therapeutic targets and potentially result in effective treatments for neurological disorders involving BBB disruption. Here in this review, we first briefly introduce the BBB and basal lamina with a focus on laminin. Next, we elucidate laminin expression and its function in BBB maintenance/repair in a cell-specific manner. Potential functional compensation among laminin isoforms is also discussed. Last, current challenges in the field and future directions are summarized. Our goal is to provide a synthetic review to encourage novel ideas and stimulate new research in the field.

Deficiency of fibroblast growth factor 2 promotes contractile phenotype of pericytes in ascending thoracic aortic aneurysm

Pericytes exhibit progenitor cell-like qualities and associate with the vasa vasorum-vital microvessels nourishing larger arteries and veins. How pericytes change in human ascending thoracic aortic aneurysm (ATAA) remains unknown. Here, we used the public single-nuclei sequencing data to reveal a contractile phenotype transition of pericytes in human ATAA specimens. In addition, we found that a protective factor, fibroblast growth factor 2 (FGF2), is decreased in the aortic adventitia of both male and female patients with ATAA and impacts pericytes. We demonstrated that FGF2 maintained pericytes in a less contractile and high angiogenic phenotype via MAPK and PI3K-AKT signaling pathways. These findings suggested the latent engagement of pericytes in ATAA, providing insights that could guide the development of new therapies against aortic disease.NEW & NOTEWORTHY Here, we revealed that pericytes transition into a contractile phenotype in human ATAA. We demonstrated that FGF2 maintained pericytes in a less contractile and high angiogenic stage via MAPK and PI3K-AKT signaling pathway, whereas we found FGF2 is decreased in the aortic adventitia of patients with ATAA. Our findings suggest how growth factor deficiency in the microenvironment affects pericytes during ATAA, offering leads for potential new therapies for aortic diseases.

Microvascularization in 3D Human Engineered Tissue and Organoids

The microvasculature, a complex network of small blood vessels, connects systemic circulation with local tissues, facilitating the nutrient and oxygen exchange that is critical for homeostasis and organ function. Engineering these structures is paramount for advancing tissue regeneration, disease modeling, and drug testing. However, replicating the intricate architecture of native vascular systems-characterized by diverse vessel diameters, cellular constituents, and dynamic perfusion capabilities-presents significant challenges. This complexity is compounded by the need to precisely integrate biomechanical, biochemical, and cellular cues. Recent breakthroughs in microfabrication, organoids, bioprinting, organ-on-a-chip platforms, and in vivo vascularization techniques have propelled the field toward faithfully replicating vascular complexity. These innovations not only enhance our understanding of vascular biology but also enable the generation of functional, perfusable tissue constructs. Here, we explore state-of-the-art technologies and strategies in microvascular engineering, emphasizing key advancements and addressing the remaining challenges to developing fully functional vascularized tissues.

Perivascular macrophages in the central nervous system: insights into their roles in health and disease

Perivascular macrophages (PVMs) are a specialized subset of macrophages situated near blood vessels in the brain. Their strategic positioning around these vessels enables them to perform key functions in immune surveillance and response to inflammation and injury. These cells are crucial for modulating the immune response within the brain, contributing to normal central nervous system (CNS) processes. In pathological conditions, the role of PVMs becomes more complex. Depending on the specific disease or injury, they may contribute to inflammation, blood-brain barrier (BBB) dysfunction, and the clearance of abnormal materials. PVMs are implicated in degenerative diseases, cerebrovascular impairment, and microhemorrhages associated with amyloid-β immunotherapy. Despite their important roles in the CNS, research on PVMs remains limited, and the mechanisms underlying their involvement in both physiological and pathological processes within the brain are not yet fully elucidated. Therefore, this review will focus on the current advancements in PVM research, including their origin, classification, roles in neuroinflammation and neuroprotection, and their potential roles as therapeutic targets for neurodegenerative diseases.

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.

Organoid Vascularization: Strategies and Applications

Organoids provide 3D structures that replicate native tissues in biomedical research. The development of vascular networks within organoids enables oxygen and nutrient delivery while facilitating metabolic waste removal, which supports organoid growth and maturation. Recent studies demonstrate that vascularized organoid models offer insights into tissue interactions and promote tissue regeneration. However, the current limitations in establishing functional vascular networks affect organoid growth, viability, and clinical translation potential. This review examines the development of vascularized organoids, including the mechanisms of angiogenesis and vasculogenesis, construction strategies, and biomedical applications. The approaches are categorized into in vivo and in vitro methods, with analysis of their specific advantages and limitations. The review also discusses emerging techniques such as bioprinting and gene editing for improving vascularization and functional integration in organoid-based therapies. Current developments in organoid vascularization indicate potential applications in modeling human diseases and developing therapeutic strategies, contributing to advances in translational research.

TAMing Gliomas: Unraveling the Roles of Iba1 and CD163 in Glioblastoma

Gliomas, the most common type of primary brain tumor, are a significant cause of morbidity and mortality worldwide. Glioblastoma, a highly malignant subtype, is particularly common, aggressive, and resistant to treatment. The tumor microenvironment (TME) of gliomas, especially glioblastomas, is characterized by a distinct presence of tumor-associated macrophages (TAMs), which densely infiltrate glioblastomas, a hallmark of these tumors. This macrophage population comprises both tissue-resident microglia as well as macrophages derived from the walls of blood vessels and the blood stream. Ionized calcium-binding adapter molecule 1 (Iba1) and CD163 are established cellular markers that enable the identification and functional characterization of these cells within the TME. This review provides an in-depth examination of the roles of Iba1 and CD163 in malignant gliomas, with a focus on TAM activation, migration, and immunomodulatory functions. Additionally, we will discuss how recent advances in AI-enhanced cell identification and visualization techniques have begun to transform the analysis of TAMs, promising unprecedented precision in their characterization and providing new insights into their roles within the TME. Iba1 and CD163 appear to have both unique and shared roles in glioma pathobiology, and both have the potential to be targeted through different molecular and cellular mechanisms. We discuss the therapeutic potential of Iba1 and CD163 based on available preclinical (experimental) and clinical (human tissue-based) evidence.

Novel Directly Reprogrammed Smooth Muscle Cells Promote Vascular Regeneration as Microvascular Mural Cells

BACKGROUND

Although cell therapy has emerged as a promising approach to promote neovascularization, its effects are mostly limited to capillaries. To generate larger or more stable vessels, layering of mural cells such as smooth muscle cells (SMCs) or pericytes is required. Recently, direct reprogramming approaches have been developed for generating SMCs. However, such reprogrammed SMCs lack genuine features of contractile SMCs, a native SMC phenotype; thus, their therapeutic and vessel-forming potential in vivo was not explored. Therefore, we aimed to directly reprogram human dermal fibroblasts toward contractile SMCs (rSMCs) and investigated their role for generating vascular mural cells in vivo and their therapeutic effects on ischemic disease.

METHODS

We applied myocardin and all-trans retinoic acid with specific culture conditions to directly reprogram human dermal fibroblasts into rSMCs. We characterized their phenotype as contractile SMCs through quantitative reverse-transcriptase polymerase chain reaction, flow cytometry, and immunostaining. We then explored their contractility using a vasoconstrictor, carbachol, and through transmission electron microscope and bulk RNA sequencing. Next, we evaluated whether transplantation of rSMCs improves blood flow and induces vessel formation as mural cells in a mouse model of hindlimb ischemia with laser Doppler perfusion imaging and histological analysis. We also determined their paracrine effects.

RESULTS

Our novel culture conditions using myocardin and all-trans retinoic acid efficiently reprogrammed human dermal fibroblasts into SMCs. These rSMCs displayed characteristics of contractile SMCs at the mRNA, protein, and cellular levels. Transplantation of rSMCs into ischemic mouse hind limbs enhanced blood flow recovery and vascular repair and improved limb salvage. Histological examination showed that vascular density was increased and the engrafted rSMCs were incorporated into the vascular wall as pericytes and vascular SMCs, thereby contributing to formation of more stable and larger microvessels. Quantitative reverse-transcriptase polymerase chain reaction analysis revealed that these transplanted rSMCs exerted pleiotropic effects, including angiogenic, arteriogenic, vessel-stabilizing, and tissue regenerative effects, on ischemic limbs.

CONCLUSIONS

A combination of myocardin and all-trans retinoic acid in defined culture conditions efficiently reprogrammed human fibroblasts into contractile and functional SMCs. The rSMCs were shown to be effective for vascular repair and contributed to neovascularization through mural cells and various paracrine effects. These human rSMCs could represent a novel source for cell-based therapy and research.

Deletion of microsomal epoxide hydrolase gene leads to increased density in cerebral vasculature and enhances cerebral blood flow in mice

Microsomal epoxide hydrolase (mEH), first identified as detoxifying enzyme, can hydrolyze epoxyeicosatrienoic acids (EETs) to less active diols (DHETs). EETs are potent vasodilatory and pro-angiogenic lipids, also implicated in neurovascular coupling. In mouse brain, mEH is strongly expressed in vascular and perivascular cells in contrast to the related soluble epoxide hydrolase (sEH), predominantly found in astrocytes. While sEH inhibition in stroke has demonstrated neuroprotective effects and increases cerebral blood flow (CBF), data regarding the role of mEH in brain are scarce. Here, we explored the function of mEH in cerebral vasculature by comparing mEH-KO, sEH-KO and WT mice. Basal cerebral volume (CBV0) was significantly higher in various mEH-KO brain areas compared to WT and sEH-KO. In line, quantification of cerebral vasculature in cortex and thalamus revealed a higher capillary density in mEH-KO, but not in sEH-KO brain. Whisker-stimulated CBF changes were by factor two higher in both mEH-KO and sEH-KO. In acutely isolated cerebral endothelial cells the loss of mEH, but not of sEH, augmented total EET levels and decreased the DHET:EET ratio. Collectively, these data suggest an important function of mEH in the regulation of cerebral vasculature and activity-modulated CBF, presumably by controlling local levels of endothelial-derived EETs.

Protective Roles of Zinc and Selenium Against Oxidative Stress in Brain Endothelial Cells Under Shear Stress

BACKGROUND

Hypertension is a major risk factor for cerebrovascular diseases due to its damaging effects on the blood-brain barrier (BBB) and associated pathologies. Oxidative stress-induced endothelial damage plays a critical role in BBB disruption, potentially leading to cognitive impairment and neurodegeneration. In this study, we investigated the protective effects of two essential trace elements, zinc (Zn) and selenium (Se), against oxidative stress in human brain endothelial cells (HBCE5i) exposed to hypertensive shear stress. Using an innovative millifluidic system (LiveBox2), which allows for the precise simulation of continuous flow conditions, we replicated the hemodynamic forces associated with hypertension.

METHODS

Cells were treated with ZnCl2 (5-50 µM) or Na2SeO3 (50-500 nM) at concentrations selected based on previous studies and confirmed by cytotoxicity assays.

RESULTS

Our results demonstrated that shear stress significantly altered the localization of the tight junction protein zonula occludens-1 (ZO-1) and induced the nuclear translocation of the transcription factor NRF2, a hallmark of oxidative stress. Importantly, treatment with 10 µM ZnCl2 preserved ZO-1 membrane localization and prevented NRF2 translocation, as confirmed by quantitative image analysis. In contrast, Na2SeO3 did not provide comparable protection, although modest improvements in ZO-1 localization were observed in some replicates.

DISCUSSION

We discuss potential reasons for selenium's limited efficacy, including differences in bioavailability and cellular uptake. Our findings underscore zinc's promising role as a neurovascular protector and suggest that further investigation into more complex in vitro models and in vivo studies is warranted.

Association between the atherogenic index of plasma and the systemic immuno-inflammatory index using NHANES data from 2005 to 2018

The atherogenic index of plasma (AIP) is used to evaluate the risk of atherosclerosis, while the systemic immune-inflammation index (SII) measures inflammation. The AIP and SII are indicators used to predict diseases in various areas. This study aims to explore the relationship between AIP and SII. A cross-sectional study design was used to recruit 70,190 participants from the National Health and Nutrition Examination Survey (NHANES) conducted between 2005 and 2018, excluding AIP missing data, SII missing data, participants under 20 years of age, and participants with missing covariates to eventually include 8163 participants. We used weighted multiple linear regression analysis, trend test, smooth curve fitting and threshold effect analysis to examine the relationship between AIP and SII. Among the 8163 participants included in the study, the mean (± SD) age was 48.412 ± 16.842 years. The mean SII (± SD) for all participants was 519.910 ± 316.974. In a model adjusted for all covariates (Model 3), AIP showed a significant positive correlation with SII [β (95% CI) 32.497 (5.425, 59.569), P = 0.021]. The smooth curve fitting results of AIP and SII are an "inverted U-shape" non-linear relationship, and the inflection point is at AIP = 0.82. This positive association between AIP and SII was found only in females and participants under 50. Specifically, for females, the positive correlation between AIP and SII was linear [β (95% CI) 80.791 (44.625, 116.958); P < 0.001]. In participants under 50, the positive correlation between AIP and SII was [β (95% CI) 34.198 (3.087, 65.310); P = 0.034], and there was also an "inverted U-shape" non-linear relationship with an inflection point of AIP = 0.549. For participants aged 20-50 years and males, the smooth curve showed a "down-flat-down" non-linear relationship. There is a significant positive correlation between AIP and SII. A positive association between AIP and SII was observed exclusively in females and among participants under 50. Furthermore, AIP and SII demonstrated a nonlinear relationship that resembles an "inverted U-shape". These findings offer new insights into the prevention, treatment, and management of cardiovascular disease. However, further comprehensive cohort studies are necessary to validate the relationship between AIP and SII.

Isolation, culture, and characterization of primary endothelial cells and pericytes from mouse sciatic nerve

BACKGROUND

The recovery of injured peripheral nerves relies on angiogenesis, where newly formed blood vessels act as pathways guiding Schwann cells across the wound to support axon regeneration. While some research has examined this process, the specific mechanisms of angiogenesis in peripheral nerve healing remain unclear. In vitro models are vital tools to investigate these mechanisms; however, no current in vitro culture methods exist for isolating vascular cells, such as endothelial cells (ECs) and pericytes, specifically from sciatic nerves.

NEW METHOD

We developed a straightforward and reliable technique for isolating ECs and pericytes from injured sciatic nerves, optimized for use in in vitro studies. Cell types were characterized using specific markers and phenotypic assessments, with flow cytometry confirming cell identity and determining cell purity.

RESULTS

Our method successfully isolated high-purity ECs and pericytes from injured sciatic nerves. Immunofluorescence analysis showed that primary cultured ECs exhibited strong positive staining for CD31, while pericytes stained strongly for NG2 and PDGFRβ. Flow cytometric analysis confirmed that ECs achieved a purity of 90.22 %, and pericytes reached a purity of 92.01 %. Both cell types were capable of forming organized capillary-like structures, and in co-culture systems, pericytes effectively wrapped around ECs.

COMPARISON WITH EXISTING METHODS

Current isolation methods for ECs and pericytes from sciatic nerves are limited. Although techniques exist for isolating these cells from other tissues, they often rely on enzymatic digestion, which can damage cell surface proteins and reduce cell viability. Our method allows for the efficient isolation of intact ECs and pericytes from sciatic nerve tissue without such drawbacks, providing a robust platform for in vitro studies.

CONCLUSIONS

This newly developed method offers an effective approach to isolate ECs and pericytes from the sciatic nerve, contributing a valuable tool for investigating the function and pathology of angiogenesis in the context of sciatic nerve injury recovery.

Cancer-associated fibroblasts in breast cancer in the single-cell era: Opportunities and challenges

Breast cancer is a leading cause of morbidity and mortality in women, and its progression is closely linked to the tumor microenvironment (TME). Cancer-associated fibroblasts (CAFs), key components of the TME, play a crucial role in promoting tumor growth by driving cancer cell proliferation, invasion, extracellular matrix (ECM) remodeling, inflammation, chemoresistance, and immunosuppression. CAFs exhibit considerable heterogeneity and are classified into subgroups based on different combinations of biomarkers. Single-cell RNA sequencing (scRNA-seq) enables high-throughput and high-resolution analysis of individual cells. Relying on this technology, it is possible to cluster complex CAFs according to different biomarkers to analyze the specific phenotypes and functions of different subpopulations. This review explores CAF clusters in breast cancer and their associated biomarkers, highlighting their roles in disease progression and potential for targeted therapies.

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.

Platelets promote metastasis of intrahepatic cholangiocarcinoma through activation of TGF-β/Smad2 pathway

Intrahepatic cholangiocarcinoma (ICC), an aggressive liver cancer, lacks simple and accurate clinical tests, which poses challenges to postoperative diagnosis and treatment. Recent studies have indicated that platelet levels might be relevant to the postoperative prognosis of ICC. However, their prognostic significance in ICC remains unclarified. This study included 218 ICC patients who underwent hepatic resection. Comprehensive analyses of patients' postoperative prognosis were conducted primarily focusing on their platelet levels associated with prognostic traits. To further investigate the underlying mechanism between platelet levels and patients' postoperative prognosis, we elucidated the association between platelets and tumor metastasis using HCCC-9810 and HUCC-T1 cells as well as mouse models. In the retrospective cohort study, elevated serum platelet levels (≥300 × 109/L) or tumoral platelet levels (≥0.23) individually indicated an unfavorable postoperative prognosis in individuals with ICC. Multivariate analysis showed that tumoral platelet levels can be an independent prognostic factor, while the loss of prognostic superiority of serum platelet levels in the analysis may be attributed to the influence of confounding inclusion variables. Epithelial/mesenchymal transition (EMT) marker expression changes in HCCC-9810 and HUCC-T1 cells with platelet treatment were analyzed to understand how platelets contribute to ICC malignant recurring progression. The significant role of the TGF-β/Smad2 pathway in ICC metastasis was identified. In addition, aspirin was found to have the potential to reduce ICC metastasis by inhibiting platelet function. In conclusion, this study indicated that ICC patients with postoperative serum platelet levels ≥300 × 109/L or tumoral platelet levels ≥0.23 have significantly higher risk of poor postoperative prognosis. This is due to platelet-derived TGFβ1 leading to EMT in ICC cells, thus promoting tumor metastasis.

Mild hypercapnia before reperfusion reduces ischemia-reperfusion injury in hyperacute ischemic stroke rat model

Endovascular thrombectomy has a recanalization rate over 80%; however, approximately 50% of ischemic stroke patients still experience dependency or mortality. Recently, clinical trials demonstrated the benefits of administering neuroprotective agents prior to endovascular thrombectomy. Additionally, recent studies showed neuroprotective effects of mild hypercapnia in patients resuscitated after cardiac arrest. However, its efficacy in ischemic stroke remains unclear. We aimed to investigate whether carbon dioxide (CO2) per-conditioning has neuroprotective effects in rat models with middle cerebral artery occlusion (MCAO). Rat models received intermittent inhalation of mixed gas during the MCAO period. After surgery, behavioral assessments, infarct size measurement, immunohistochemistry, and western blot analysis were performed. We found CO2 per-conditioning reduced infarct size and neurological deficit. The number of 8-hydroxy-2-deoxyguanosine (8-OHdG) positive cells and matrix metalloproteinase 9 (MMP-9)/platelet derived growth factor receptor beta (PDGFRβ) double positive cells were significantly decreased after CO2 per-conditioning. The expressions of tight junction protein and pericytes survival were preserved. This study underscores mild hypercapnia before reperfusion not only reduces neurologic deficit and infarct size, but also maintains the integrity of the blood-brain barrier and neurovascular unit, alongside mitigating oxidative stress in hyperacute stroke rat models. Therapeutic mild hypercapnia before reperfusion is promising and requires further clinical application.

Multifaceted Role of Notch Signaling in Vascular Health and Diseases

Notch signaling is evolutionarily conserved from Drosophila to mammals and it functions as an essential modulator of vascular growth and development by directing endothelial cell specification, proliferation, migration, arteriovenous differentiation, inflammation, and apoptosis. The interplay between Notch and other signaling pathways plays a homeostatic role by modulating multiple vascular functions, including permeability regulation, angiogenesis, and vascular remodeling. This review explores current knowledge on Notch signaling in vascular development, homeostasis, and disease. It also discusses recent developments in understanding how endothelial Notch signaling affects vascular inflammation via cytokines or aberrant shear stress in endothelial cells while addressing the reciprocal relationship between Notch signaling and inflammation.

Smoking aggravates neovascular age-related macular degeneration via Sema4D-PlexinB1 axis-mediated activation of pericytes

Age-related macular degeneration (AMD) is a prevalent neuroinflammation condition and the leading cause of irreversible blindness among the elderly population. Smoking significantly increases AMD risk, yet the mechanisms remain unclear. Here, we investigate the role of Sema4D-PlexinB1 axis in the progression of AMD, in which Sema4D-PlexinB1 is highly activated by smoking. Using patient-derived samples and mouse models, we discover that smoking increases the presence of Sema4D on the surface of CD8+ T cells that migrate into the choroidal neovascularization (CNV) lesion via CXCL12-CXCR4 axis and interact with its receptor PlexinB1 on choroidal pericytes. This leads to ROR2-mediated PlexinB1 phosphorylation and pericyte activation, thereby disrupting vascular homeostasis and promoting neovascularization. Inhibition of Sema4D reduces CNV and improves the benefit of anti-VEGF treatment. In conclusion, this study unveils the molecular mechanisms through which smoking exacerbates AMD pathology, and presents a potential therapeutic strategy by targeting Sema4D to augment current AMD treatments.

Periarteriolar niches become inflamed in aging bone marrow, remodeling the stromal microenvironment and depleting lymphoid progenitors

In early postnatal and young adult bone marrow, Leptin receptor-expressing (LepR+) stromal cells and endothelial cells synthesize factors required for hematopoietic stem cell (HSC) maintenance, including Stem Cell Factor (SCF) and Cxcl12. However, little is known about how these stromal cells change during aging. We performed single-cell RNA sequencing of mouse bone marrow stromal cells at 2, 12, and 24 mo of age. We identified five transcriptionally distinct subsets of LepR+ cells, all of which expressed the highest levels of Scf and Cxcl12 in bone marrow throughout adult life. In aging bone marrow, SCF from LepR+ cells, but not endothelial cells, continued to be necessary for the maintenance of HSCs and early restricted progenitors. However, arteriolar endothelial cells and other periarteriolar cells expressed increasing levels of interferon during aging. This increased the numbers of periarteriolar Sca1+Cxcl9+LepR+ cells with an inflammatory gene signature and depleted lymphoid progenitors, at least some of which are also periarteriolar. The periarteriolar environment thus became particularly inflamed during aging, remodeling the stromal microenvironment and depleting lymphoid progenitors in an interferon-dependent manner.

Exploration of Conserved Human Adipose Subpopulations Using Targeted Single-Nuclei RNA Sequencing Data Sets

BACKGROUND

Smooth-muscle cells and pericytes are mural cells. Pericytes can differentiate into myofibroblasts, chondrocytes, vascular smooth-muscle cells, and adipocytes, marking them as a distinct progenitor population. Our goal was to molecularly define the progenitor cell populations in human adipose tissues and test the adipogenic potential of human mural cells.

METHODS

We used informatic analysis of single-cell RNA sequencing data from human tissues to identify and define pericytes and adipose progenitor cells found in human adipose tissues, including perivascular, brown, and white adipose tissues.

RESULTS

We established tissue-specific patterns of gene expression in pericytes and other putative human adipocyte progenitor cells. PPARG-expressing pericytes were present in multiple human adipose depots with consistent expression of COL25A1, MYO1B, and POSTN. We also found evidence of tissue-specific pericyte markers. Although there is some conservation between human and mouse adipose tissues, human pericyte populations have unique, depot-specific gene expression signatures. Immunofluorescence staining of human adipose tissue revealed the presence of pericytes both distant from and adjacent to vasculature in human adipose tissue. Additionally, we demonstrated the potential of human brain pericytes and aortic vascular smooth-muscle cells to differentiate into adipocytes in vitro on the basis of intracellular lipid accumulation and expression of adipocyte markers.

CONCLUSIONS

Human adipose cell populations are distinct from mice, and the pericyte subpopulation in human adipose tissues are present across adipose depots. Given that vascular mural cells, including pericytes and smooth-muscle cells, can undergo adipogenesis, we postulate that they are a novel source of adipocytes in the vascular microenvironment.

Cd248a regulates pericyte development and viability in zebrafish

CD248 is a pericyte marker during embryonic and tumor neovascularization. Although its expression pattern and function in mammalian pericytes have been extensively studied, its role in zebrafish pericytes remains largely unexplored. In this study, we identify that among the two zebrafish orthologs of human CD248, cd248a, rather than cd248b, is predominantly expressed in pericytes during embryonic development. We generate cd248a and cd248b mutant zebrafish (cd248acc11/cc11 and cd248bcc12/cc12) and observe a significant reduction in pericyte numbers in cd248acc11/cc11 mutants, accompanied by disruption of the blood-brain barrier. Notably, treatment with AG1295, a platelet-derived growth factor receptor inhibitor, attenuates the increase in pericyte proliferation induced by cd248a overexpression. Additionally, we find that CoCl2-induced pericyte apoptosis is enhanced in cd248acc11/cc11 larvae, indicating that cd248a provides protection against hypoxia-induced apoptosis. Taken together, our findings elucidate the role and underlying mechanisms of cd248a in regulating pericyte proliferation and apoptosis in zebrafish.

TNAP expressing adventitial pericytes contribute to myogenesis during foetal development

OBJECTIVE

During growth and differentiation of skeletal muscle, cell types other than canonical myoblasts can be recruited to a myogenic fate. Among these, TNAP+ pericytes can differentiate into skeletal or smooth muscle cells during postnatal growth and contribute to muscle regeneration. However, their role in muscle development has not been investigated. This study aims to characterise pericyte fate choices during embryonic and foetal myogenesis, occurring in the second half of gestation.

APPROACH AND RESULTS

Using Cre-loxP lineage tracing with multiple reporters including the multifluorescent Confetti, we labelled TNAP+ precursors in vivo and assessed the smooth or skeletal muscle differentiation in their lineage at a perinatal stage. We found that TNAP+ cells contribute in vivo to skeletal and smooth muscle cells, as well as other pericytes, also during pre-natal muscle development. The resulting clones showed that such fate choices are likely to depend on distinct unipotent progenitors rather than multipotent progenitors. In addition, we isolated and differentiated in vitro foetal cells derived from TNAP+ precursors, which showed that they are not spontaneously myogenic unless co-cultured with other skeletal muscle cells.

CONCLUSIONS

This work extends our understanding of the differentiative potency of these non- canonical skeletal muscle progenitors during prenatal life, with a view to a future application of this knowledge to optimise cell therapies for muscle wasting disorders.

Functional Characterization of the Hephaestin Variant D568H Provides Novel Mechanistic Insights on Iron-Dependent Asbestos-Induced Carcinogenesis

A local disruption of iron homeostasis leading to oxidative stress is considered one of the main mechanisms of asbestos-related genotoxicity. Another aspect contributing to the risk of developing pathological consequences upon asbestos exposure is individual genetic factors. In a previous study, we identified a coding SNP in the hephaestin gene (HEPH) that protects against developing asbestos-related thoracic cancer. Heph is a ferroxidase that promotes iron export in concert with the permease ferroportin (Fpn1). Here, we performed an in-depth functional characterization of the HephD568H variant to gain insights into the molecular basis of its protective activity. We showed that HephD568H forms a complex with Fpn1 and possesses full ferroxidase activity. Although HephD568H is more efficiently recruited to the plasma membrane, it is impaired in binding iron-deficient Tfn, whose interaction with wild-type (WT) ferroxidase emerged as a novel mechanism to perceive brain iron needs. Heph is expressed in the human lung by pericytes and fibroblasts, and lung pericytes were shown to respond to iron demand by upregulating the iron exporter pair. These results extend the paradigm of local iron regulation discovered at the blood-brain barrier to the pulmonary vasculature. Furthermore, they establish a mechanistic link between changes in iron sensing and the risk of developing asbestos-related malignancies.

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.

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.

Therapeutic Targeting of Pattern Recognition Receptors to Modulate Inflammation in Atherosclerosis

Atherosclerosis (AS), a potentially fatal cardiovascular disease (CVD), is a chronic inflammatory condition. The disease's onset and progression are influenced by inflammatory and immunological mechanisms. The innate immune pathways are essential in the progression of AS, as they are responsible for detecting first danger signals and causing long-term changes in immune cells. The innate immune system possesses distinct receptors known as pattern recognition receptors (PRRs) which can identify both pathogen-associated molecular patterns and danger-associated molecular signals. Activation of PRRs initiates the inflammatory response in various physiological systems, such as the cardiovascular system. This review specifically examines the contribution of the innate immune response and PRRs to the formation and advancement of AS. Studying the role of these particular receptors in AS would enhance our understanding of the development of AS and offer novel approaches for directly improving the inflammatory response associated with it.

Biomaterial-Based Regenerative Strategies for Volumetric Muscle Loss: Challenges and Solutions

Significance: Volumetric muscle loss (VML) is caused by the loss of significant amounts of skeletal muscle tissue. VML cannot be repaired by intrinsic regenerative processes, resulting in permanent loss of muscle function and disability. Current rehabilitative-focused treatment strategies lack efficacy and do not restore muscle function, indicating the need for the development of effective regenerative strategies. Recent Advances: Recent developments implicate biomaterial-based approaches for promoting muscle repair and functional restoration post-VML. Specifically, bioscaffolds transplanted in the injury site have been utilized to mimic endogenous cues of the ablated tissue to promote myogenic pathways, increase neo-myofiber synthesis, and ultimately restore contractile function to the injured unit. Critical Issues: Despite the development and preclinical testing of various biomaterial-based regenerative strategies, effective therapies for patients are not available. The unique challenges posed for biomaterial-based treatments of VML injuries, including its scalability and clinical applicability beyond small-animal models, impede progress. Furthermore, production of tissue-engineered constructs is technically demanding, with reproducibility issues at scale and complexities in achieving vascularization and innervation of large constructs. Future Directions: Biomaterial-based regenerative strategies designed to comprehensively address the pathophysiology of VML are needed. Considerations for clinical translation, including scalability and regulatory compliance, should also be considered when developing such strategies. In addition, an integrated approach that combines regenerative and rehabilitative strategies is essential for ensuring functional improvement.

Development of Immunostaining Protocols for 3D Visualization of Pericytes in Human Retinal Flatmounts

Vascular pericytes are widely present across the human body and crucial in regulating vascular flow, permeability, and homeostasis. In the human retina, pericytes are important for forming and maintaining the blood-retinal barrier, as well as for autoregulation of blood flow. Pericyte loss has been implicated in various pathological conditions. Visualization of pericytes by immunofluorescence (IF) staining provides valuable information on pericyte number, morphology, location, and on expression of anatomic and functional markers. However, species-specific differences in pericyte marker expression exist. In this study, we aimed to develop a novel IF co-staining protocol to detect the pericyte markers NG2, PDGFRβ, αSMA, CD13, and RFC1 in human retinal flatmounts. Unlike retinal sections, retinal flatmounts enable 3D visualization of pericyte distribution across the entire vascular network. Key optimizations included tailoring the fixation method, blocking buffer composition and antibody solvent, as well as using jasplakinolide to enhance αSMA detection. Our protocol successfully enabled double staining of NG2 and PDGFRβ, as well as αSMA and PDGFRβ, whereas CD13 and RFC1 expression was not detectable in human retinal flatmounts. This novel 3D IF protocol enhances in situ visualization of human retinal pericytes, enabling accurate studies of their role in vascular health and disease to aid targeted therapy development.

Elucidating shared genetic association between female body mass index and preeclampsia

The prevalence of obesity is steadily rising and poses a significant challenge to women's health. Preeclampsia (PE), a leading cause of maternal and fetal mortality, is significantly linked to a high body mass index (BMI). However, the shared genetic architecture underlying these conditions remains poorly understood. In this study, we used summary-level data from large-scale genome-wide association studies of BMI (N = 434,794) and PE (Ncases = 8185; Ncontrols = 234,147) to assess the shared genetic architecture between them. Our findings revealed a significant genetic correlation between BMI and PE, with an estimated sample overlap of approximately 0.8%. We identified roughly 1100 shared genetic variants, with the most notable region of local genetic correlation located in 16q12.2. Enrichment analyses highlighted endothelial dysfunction as a key biological mechanism linking BMI and PE. Additionally, RABEP2 was identified as a novel shared risk gene. Mendelian randomization analysis demonstrated a bidirectional causal relationship between BMI and PE, with blood pressure identified as a key mediator. We identified the shared genetic foundation between BMI and PE, providing valuable insights into the comorbidity of these conditions and offering a new framework for future research into comorbidity.

The Triad of Blood-Brain Barrier Integrity: Endothelial Cells, Astrocytes, and Pericytes in Perinatal Stroke Pathophysiology

Pediatric stroke, a significant cause of long-term neurological deficits in children, often arises from disruptions within neurovascular unit (NVU) components. The NVU, a dynamic ensemble of astrocytes, endothelial cells, pericytes, and microglia, is vital for maintaining cerebral homeostasis and regulating vascular brain development. Its structural integrity, particularly at the blood-brain barrier (BBB), depends on intercellular junctions and the basement membrane, which together restrict paracellular transport and shield the brain from systemic insults. Dysfunction in this intricate system is increasingly linked to pediatric stroke and related cerebrovascular conditions. Mutations disrupting endothelial cell adhesion or pericyte-endothelial interactions can compromise BBB stability, leading to pathological outcomes such as intraventricular hemorrhage in the germinal matrix, a hallmark of vascular brain immaturity. Additionally, inflammation, ferroptosis, necroptosis, and autophagy are key cellular processes influencing brain damage and repair. Excessive activation of these mechanisms can exacerbate NVU injury, whereas targeted therapeutic modulation offers potential pathways to mitigate damage and support recovery. This review explores the cellular and molecular mechanisms underlying NVU dysfunction, BBB disruption, and subsequent brain injury in pediatric stroke. Understanding the interplay between genetic mutations, environmental stressors, and NVU dynamics provides new insights into stroke pathogenesis. The susceptibility of the germinal matrix to vascular rupture further emphasizes the critical role of NVU integrity in early brain development. Targeting inflammatory pathways and cell death mechanisms presents promising strategies to preserve NVU function and improve outcomes for affected neonates.

Emerging role of mesenchymal cells in cardiac and cerebrovascular diseases: Physiology, pathology, and therapeutic implications

In recent years, the therapeutic utility of mesenchymal stem cells (MSCs) has received substantial attention from investigators, owing to their pleiotropic properties. The emerging insights from the developments in tissue engineering provide perspectives for the repair of damaged tissue and the replacement of failing organs. Perivascular cells including MSC-like pericytes, vascular smooth muscles, and other cells located around blood vessels, have been acknowledged to contribute to in situ angiogenesis and repair process. MSCs offer a wide array of therapeutic applications in different pathological states. However, in the current article, we have highlighted the recent updates on MSCs and their key applications in cardiac and cerebrovascular diseases, evident in different preclinical and clinical studies. We believe the present article would assist the investigators in understanding the recent advances of MSCs and exploring their therapeutic potential in varied ailments, especially cardiac and cerebrovascular diseases.

Cdc42 is crucial for mural cell migration, proliferation and patterning of the retinal vasculature

AIMS

Mural cells constitute the outer lining of blood vessels and are essential for vascular development and function. Mural cell loss or malfunction has been associated with numerous diseases including diabetic retinopathy, stroke and amyotrophic lateral sclerosis. In this work, we investigate the role of CDC42 in mural cells in vivo, using the developing mouse retina as a model.

METHODS

In this study, we generated a mouse model for Cdc42 deletion in mural cells by crossing Pdgfrb-CreERT2 mice with Cdc42flox/flox mice. This model (Cdc42iΔMC) allowed us to investigate the role of CDC42 in pericytes and smooth muscle cells in the developing and adult retinal vasculature.

RESULTS

We find that, during postnatal development, CDC42 is required in both, pericytes and smooth muscle cells to maintain proper cell morphology, mural cell coverage and distribution. During retinal angiogenesis, Cdc42-depleted pericytes lag behind the sprouting front and exhibit decreased proliferation. Consequently, capillaries at the sprouting front remain pericyte deprived, become dilated and are prone to increased vascular leakage. In addition, arteries and arterioles deviate from their normal growth directions and trajectory. While in the adult retina, mural cell coverage normalizes and pericytes adopt a normal morphology, smooth muscle cell morphologies remain abnormal and arteriolar branching angles are markedly reduced.

CONCLUSIONS

Our findings demonstrate that CDC42 is required for mural cell migration and proliferation and suggest that mural cells are essential for normal morphogenesis and patterning of the developing retinal vasculature.

Single-Cell Multi-omics Assessment of Spinal Cord Injury Blocking via Cerium-doped Upconversion Antioxidant Nanoenzymes

Spinal cord injury (SCI) impairs the central nervous system and induces the myelin-sheath-deterioration because of reactive oxygen species (ROS), further hindering the recovery of function. Herein, the simultaneously emergency treatment and dynamic luminescence severity assessment (SETLSA) strategy is designed for SCI based on cerium (Ce)-doped upconversion antioxidant nanoenzymes (Ce@UCNP-BCH). Ce@UCNP-BCH can not only efficiently eliminate the SCI localized ROS, but dynamically monitor the oxidative state in the SCI repair process using a ratiometric luminescence signal. Moreover, the classic basso mouse scale score and immunofluorescence analysis together exhibit that Ce@UCNP-BCH effectively facilitates the regeneration of spinal cord including myelin sheath, and promotes the functional recovery of SCI mice. Particularly, the study combines snATAC-eq and snRNA-seq to reveal the heterogeneity of spinal cord tissue following Ce@UCNP-BCH treatment. The findings reveal a significant increase in myelinating oligodendrocytes, as well as higher expression of myelination-related genes, and the study also reveals the gene regulatory dynamics of remyelination after treatment. Besides, the ETLSA strategy synergistically boosts ROS consumption through the superoxide dismutase (SOD)-related pathways after SOD-siRNA treatment. In conclusion, this SETLSA strategy with simultaneously blocking and dynamic monitoring oxidative stress has enriched the toolkit for promoting SCI repair.

Specialized pericyte subtypes in the pulmonary capillaries

Pericytes are essential for capillary stability and homeostasis, with impaired pericyte function linked to diseases like pulmonary arterial hypertension. Investigating pericyte biology has been challenging due to the lack of specific markers, making it difficult to distinguish pericytes from other stromal cells. Using bioinformatic analysis and RNAscope, we identified Higd1b as a unique gene marker for pericytes and subsequently generated a knock-in mouse line, Higd1b-CreERT2, that accurately labels pericytes in the lung and heart. Single-cell RNA sequencing revealed two distinct Higd1b+ pericyte subtypes: while Type 1 pericytes support capillary homeostasis, Type 2 pericytes accumulate in arterioles, and co-express smooth muscle markers and higher levels of vimentin under hypoxic conditions. Lastly, healthy human lung pericytes with upregulation of vimentin exhibited increased adhesion, migration, and higher expression levels of the smooth muscle marker SM22 in vitro. These findings highlight the specialization of pulmonary pericytes and their contribution to vascular remodeling during hypoxia-induced pulmonary hypertension.

Neurovascular coupling: a review of spontaneous neocortical dynamics linking neuronal activity to hemodynamics and what we have learned from the rodent brain

The brain is a complex neural network whose functional dynamics offer valuable insights into behavioral performance and health. Advances in fMRI have provided a unique window into studying human brain networks, providing us with a powerful tool for clinical research. Yet many questions about the underlying correlates between spontaneous fMRI and neural activity remain poorly understood, limiting the impact of this research. Cross-species studies have proven essential in deepening our understanding of how neuronal activity is coupled to increases in local cerebral blood flow, changes in blood oxygenation, and the measured fMRI signal. In this article, we review some fundamental mechanisms implicated in neurovascular coupling. We then examine neurovascular coupling within the context of spontaneous cortical functional networks and their dynamics, summarizing key findings from mechanistic studies in rodents. In doing so, we highlight the nuances of the neurovascular coupling that ultimately influences the interpretation of derived hemodynamic functional networks, their dynamics, and the neural underpinnings they represent.