Pericytes in the disease spotlight

Microvascular immunity is organ-specific and remodeled after kidney injury in mice

Many studies analyze tissue-resident or blood-borne leukocytes to monitor disease progression. We hypothesized that the microvasculature serves as a distinct site for immune cell activity. Here, we investigate microvascular leukocyte phenotypes before, during and after acute kidney injury (AKI) in mice, uncovering unique characteristics in the kidney, liver, and lung. Using single-cell sequencing, we identify several immune cells that were up to 100-fold expanded in the kidney vasculature, including macrophages, dendritic cells (DC), and B cells. Regeneration after AKI is characterized by sustained remodeling of the renal microvascular interface. Homeostatic microvascular C1q+ macrophages withdraw from the vascular barrier which is subsequently repopulated by new subsets, including CD11c+F480+ and CD11c+F480- cells. These newly arrived macrophages exhibit enhanced phagocytic activity toward circulating bacteria and secretion of tumor necrosis factor, pointing to maladaptive repair mechanisms after AKI. These data suggest organ- and disease-specific microvascular immune dynamics which are not detectable through conventional blood and tissue analysis.

CAVIN3 deficiency promotes vascular normalization in ocular neovascular disease via ERK/JAG1 signaling pathway

Multiple members of the caveolae-associated protein (Cavin) family are implicated in angiogenesis. However, the specific role of CAVIN3 in pathological angiogenesis within the eye remains unclear. The present study demonstrated that CAVIN3 knockdown in endothelial cells (ECs) promoted vascular normalization in ocular pathological neovascularization. Elevated CAVIN3 expression was observed in the ECs of retinal pigment epithelium/choroid complexes from patients with neovascular age-related macular degeneration and fibrovascular membranes from patients with proliferative diabetic retinopathy. Additionally, upregulated Cavin3 expression was detected in laser-induced choroidal neovascularization (CNV) and oxygen-induced retinopathy (OIR) mouse models. In both OIR and CNV mice, Cavin3 knockdown inhibited pathological neovascularization. Cavin3 deficiency further disrupted EC proliferation and vascular sprouting, thereby promoting vascular normalization by partially restoring microenvironmental hypoxia and reestablishing pericyte-EC interactions. Mechanistically, we demonstrated that zinc finger E-box-binding homeobox 1 (ZEB1) regulated CAVIN3 transcription in ECs under hypoxic conditions. CAVIN3 deficiency modulated pathological vascularization by inhibiting ERK phosphorylation, which downregulated jagged 1 (JAG1) expression. Conclusively, this study elucidated the protective role of endothelial CAVIN3 deficiency in pathological neovascularization models, addressing a gap in understanding the regulatory role of Cavins in angiogenesis. These findings suggested a therapeutic direction for ocular neovascular diseases.

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.

Isolation and Culture of Primary Pericytes from Mouse

Pericytes are essential for tissue homeostasis, functioning to regulate capillary blood flow. Dysfunctional pericytes are implicated in various pathologies, including cancer progression. Despite their important function in both health and disease, pericytes remain understudied due to a lack of robust model systems that accurately reflect their in vivo biology. Here, we present a comprehensive protocol for isolating and culturing primary pericytes from murine lung, brain, bone, and liver tissues, based on NG2 expression using an antibody-conjugated magnetic bead approach. Our protocol emphasizes the importance of physiological oxygen tension during ex vivo culture (10% O2 for lung pericytes and 5% O2 for brain, bone, and liver pericytes). These conditions stabilize the expression of characteristic pericyte markers at both the transcriptional and protein levels. Importantly, we optimized growth conditions to limit the expression of the plasticity factor Klf4 in order to prevent spontaneous phenotypic switching in vitro. This protocol provides a reliable and reproducible method for obtaining pericytes suitable for high-throughput analyses in order to explore pericyte biology in both physiological and pathological contexts. Key features • Isolation of primary pericytes from mouse lung, brain, bone, and liver. • Emphasis on physioxic culturing conditions to better maintain pericyte phenotype. • Representative of pericyte biology in both health and disease contexts.

In vivo programming of adult pericytes aids axon regeneration by providing cellular bridges for SCI repair

Pericytes are contractile cells of the microcirculation that participate in wound healing after spinal cord injury (SCI). Thus far, the extent to which pericytes cause or contribute to axon growth and regeneration failure after SCI remains controversial. Here, we found that SCI leads to profound changes in vasculature architecture and pericyte coverage. We demonstrated that pericytes constrain sensory axons on their surface, causing detrimental structural and functional changes in adult dorsal root ganglion neurons that contribute to axon regeneration failure after SCI. Perhaps more excitingly, we discovered that in vivo programming of adult pericytes via local administration of platelet-derived growth factor BB (PDGF-BB) effectively promotes axon regeneration and recovery of hindlimb function by contributing to the formation of cellular bridges that span the lesion. Ultrastructural analysis showed that PDGF-BB induced fibronectin fibril alignment and extension, effectively converting adult pericytes into a permissive substrate for axon growth. In addition, PDGF-BB localized delivery positively affects the physical and chemical nature of the lesion environment, thereby creating more favorable conditions for SCI repair. Thus, therapeutic manipulation rather than wholesale ablation of pericytes can be exploited to prime axon regeneration and SCI repair.

Cardiac Fibrosis in the Multi-Omics Era: Implications for Heart Failure

Cardiac fibrosis, a hallmark of heart failure and various cardiomyopathies, represents a complex pathological process that has long challenged therapeutic intervention. High-throughput omics technologies have begun revolutionizing our understanding of the molecular mechanisms driving cardiac fibrosis and are providing unprecedented insights into its heterogeneity and progression. This review provides a comprehensive analysis of how techniques-encompassing genomics, epigenomics, transcriptomics, proteomics, and metabolomics-are providing insight into our understanding of cardiac fibrosis. Genomic studies have identified novel genetic variants and regulatory networks associated with fibrosis susceptibility and progression, and single-cell transcriptomics has unveiled distinct cardiac fibroblast subpopulations with unique molecular signatures. Epigenomic profiling has revealed dynamic chromatin modifications controlling fibroblast activation states, and proteomic analyses have identified novel biomarkers and potential therapeutic targets. Metabolomic studies have uncovered important alterations in cardiac energetics and substrate utilization during fibrotic remodeling. The integration of these multi-omic data sets has led to the identification of previously unrecognized pathogenic mechanisms and potential therapeutic targets, including cell-type-specific interventions and metabolic modulators. We discuss how these advances are driving the development of precision medicine approaches for cardiac fibrosis while highlighting current challenges and future directions in translating multi-omic insights into effective therapeutic strategies. This review provides a systems-level perspective on cardiac fibrosis that may inform the development of more effective, personalized therapeutic approaches for heart failure and related cardiovascular diseases.

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.

Endothelial-pericyte interactions regulate angiogenesis via VEGFR2 signaling during retinal development and disease

Pericytes stabilize the microvasculature by enhancing endothelial barrier integrity, resulting in functional networks. During retinal development, pericyte recruitment is crucial for stabilizing nascent angiogenic vasculature. However, in adulthood, disrupted endothelial-pericyte interactions lead to vascular dropout and pathological angiogenesis in ocular microvascular diseases, and strategies to stabilize the retinal vasculature are lacking. We demonstrate that direct endothelial-pericyte contact downregulates pVEGFR2 in endothelial cells, which enhances pericyte migration and promotes endothelial cell barrier function. Intravitreal injection of a VEGFR2 inhibitor in mouse models of the developing retina and oxygen-induced retinopathy increased pericyte recruitment and aided vascular stability. The VEGFR2 inhibitor further rescued ischemic retinopathy by enhancing vascularization and tissue growth while reducing vascular permeability. Our findings offer a druggable target to support the growth of functional and mature microvasculature in ocular microvascular diseases and tissue regeneration overall.

Single-cell transcriptomics of clinical grade adipose-derived regenerative cells reveals consistency between donors independent of gender and BMI

Adipose-derived regenerative cells (ADRCs) also referred to as the stromal vascular fraction, provide an ample source of stem cells with widespread regenerative therapeutic use. Being heterogenous in nature, possibly affecting the clinical outcome after stem cell treatment, the ADRC- donor, -BMI, and -gender may have a large impact on ADRC composition and quality but this remains largely unexplored. Herein, we provide a comprehensive single-cell RNA sequencing ADRC mapping across two cell trial intervention studies but found no gender- or BMI-related variations, except for a minor female increase in PI16/CD55-expressing stem cells. Indeed, ADRC heterogeneity was surprisingly minimal between donors. This provides important decision-making support on adipose stem cell donor selection for stem cell treatments, and suggest that donor, gender and BMI should be regarded as less influential.

The adaptive immune system in the retina of diabetics

As the prevalence of diabetes mellitus increases each year, its most common microvascular complication, diabetic retinopathy (DR), is also on the rise. DR is now regarded as an inflammatory disease in which innate immunity plays a crucial role, and a large number of innate immune cells with associated cytokines are involved in the pathologic process of DR. The role of adaptive immunity in DR is seldom mentioned, probably due to the general perception of the immune privileged environment of the retina; however, in recent years there has been a gradual increase in research on the role of adaptive immunity in DR, and with the discovery of the retinal lymphatic system, it seems that the role of adaptive immunity can no longer be ignored. Here, we discuss the immunosuppressive environment of the retina, the phenomenon and potential mechanisms of lymphocyte infiltration in DR, and the role of the adaptive immune system in the diabetic retina, which may point the way for future research.

Mural cell dysfunction contributes to diastolic heart failure by promoting endothelial dysfunction and vessel remodelling

BACKGROUND

Heart failure with preserved ejection fraction (HFpEF) is a complex cardiovascular disease associated with metabolic comorbidities. Microvascular dysfunction has been proposed to drive HFpEF, likely via endothelial cell (EC) dysfunction, yet the role of the mural cells herein has never been explored.

METHODS

We used the diabetic db/db mouse given 1% salt as a new model of HFpEF and crossed then with PDGFRβtg/tg-CreERT2-EYFPtg/tg mice to label the mural cells. We combined single-cell RNA sequencing, NichetNet analysis and histology to determine the role of mural cell dysfunction in HFpEF.

RESULTS

Db/db mice given 1% salt for 8 weeks developed diastolic dysfunction preceded by capillary density loss, pericyte loss and vessel regression. At 4 weeks of salt, hearts of db/db mice already showed EC dysfunction associated with an anti-angiogenic signature, and an increase in pericyte-EC intracellular space. Db/db + salt hearts were further characterised by increased ACTA2 expression, arteriole wall thickening and vessel enlargement. NicheNet analysis on the single cell transcriptomic data revealed little signalling from the ECs to the mural cells; instead, mural cells signalled strongly to ECs. Mechanistically, pericyte dysfunction induces an EC growth arrest via TNFα-dependent paracrine signalling and downstream signalling through STAT1.

CONCLUSION

Mural cell dysfunction contributes to HFpEF by inducing coronary vessel remodelling, at least in part by reducing EC proliferation and inducing EC inflammation through TNFα-dependent paracrine signalling.

Matrix Viscoelasticity Controls Differentiation of Human Blood Vessel Organoids into Arterioles and Promotes Neovascularization in Myocardial Infarction

Stem cell-derived blood vessel organoids are embedded in extracellular matrices to stimulate vessel sprouting. Although vascular organoids in 3D collagen I-Matrigel gels are currently available, they are primarily capillaries composed of endothelial cells (ECs), pericytes, and mesenchymal stem-like cells, which necessitate mature arteriole differentiation for neovascularization. In this context, the hypothesis that matrix viscoelasticity regulates vascular development is investigated in 3D cultures by encapsulating blood vessel organoids within viscoelastic gelatin/β-CD assembly dynamic hydrogels or methacryloyl gelatin non-dynamic hydrogels. The vascular organoids within the dynamic hydrogel demonstrate enhanced angiogenesis and differentiation into arterioles containing smooth muscle cells. The dynamic hydrogel mechanical microenvironment promotes vascular patterning and arteriolar differentiation by elevating notch receptor 3 signaling in mesenchymal stem cells and downregulating platelet-derived growth factor B expression in ECs. Transplantation of vascular organoids in vivo, along with the dynamic hydrogel, leads to the reassembly of arterioles and restoration of cardiac function in infarcted hearts. These findings indicate that the viscoelastic properties of the matrix play a crucial role in controlling the vascular organization and differentiation processes, suggesting an exciting potential for its application in regenerative medicine.

Unraveling the transcriptomic landscape of brain vascular cells in dementia: A systematic review

INTRODUCTION

Cerebrovascular dysfunction plays a critical role in the pathogenesis of dementia and related neurodegenerative disorders. Recent omics-driven research has revealed associations between vascular abnormalities and transcriptomic alterations in brain vascular cells, particularly endothelial cells (ECs) and pericytes (PCs). However, the impact of these molecular changes on dementia remains unclear.

METHODS

We conducted a comparative analysis of gene expression in ECs and PCs across neurodegenerative conditions, including Alzheimer's disease (AD), Huntington's disease, and arteriovenous malformation, utilizing transcriptomic data from published postmortem human tissue studies.

RESULTS

We identified differentially expressed genes (DEGs) consistently dysregulated in ECs and PCs across these pathologies. Notably, several DEGs are linked to vascular cell zonation and genetic risks for AD and cerebral small vessel disease.

DISCUSSION

Our findings provide insights into the cellular and molecular mechanisms underlying vascular dysfunction in dementia, highlight the knowledge gaps, and suggest potential novel vascular therapeutic targets, including genes not previously investigated in this context.

HIGHLIGHTS

Systematic review of differentially expressed genes (DEGs) in vascular cells from neurodegenerative single-nuclear RNA-sequencing (snRNA-seq) studies. Identify overlapping DEGs in multiple vascular cell types across studies. Examine functional relevance and associations with genetic risk for common DEGs. Outline future directions for the vascular omics field.

Stromal vascular fraction: Mechanisms and application in reproductive disorders

Stromal vascular fraction (SVF) is a complex mixture derived from adipose tissue, consisting of a variety of cells. Due to its potential for tissue repair, immunomodulation, and support of angiogenesis, SVF represents a promising frontier in regenerative medicine and offers potential therapy for a range of disease conditions. In this article, we delve into the mechanisms through which SVF exerts its effects and explore its potential applications in treating both male and female reproductive disorders, including erectile dysfunction, testicular injury, stress urinary incontinence and intrauterine adhesion.

Analysis of cellular NO-GC expression in the murine heart and lineage determination in angiotensin II-induced fibrosis

NO-sensitive guanylyl cyclase (NO-GC) is involved in the (patho)physiology of the mammalian heart. However, little is known about the individual cardiac cell types that express NO-GC and the role of the enzyme in cardiac fibrosis. Here, we describe the cellular expression of NO-GC in healthy and fibrotic murine myocardium; these data were compared with scRNA-seq data. In healthy myocardium, NO-GC is strongly expressed in pericytes and smooth muscle cells but not in endothelial cells or cardiomyocytes. Angiotensin II induced cardiac hypertrophy and fibrosis; fibrotic lesions contained cells positive for NO-GC identified as activated fibroblasts. Lineage tracing indicates that NO-GC-expressing activated fibroblasts originate from PDGFRβ- and Tcf21-positive fibroblast precursors. Our data indicate NO-GC expression in cardiac pericytes and SMC in naive myocardium and in activated fibroblast in fibrotic heart tissue. NO-mediated signaling may modulate fibrotic responses underlying the action of NO-GC stimulators used in the therapy of heart failure.

Single-cell sequencing in diabetic retinopathy: progress and prospects

Diabetic retinopathy is a major ocular complication of diabetes, characterized by progressive retinal microvascular damage and significant visual impairment in working-age adults. Traditional bulk RNA sequencing offers overall gene expression profiles but does not account for cellular heterogeneity. Single-cell RNA sequencing overcomes this limitation by providing transcriptomic data at the individual cell level and distinguishing novel cell subtypes, developmental trajectories, and intercellular communications. Researchers can use single-cell sequencing to draw retinal cell atlases and identify the transcriptomic features of retinal cells, enhancing our understanding of the pathogenesis and pathological changes in diabetic retinopathy. Additionally, single-cell sequencing is widely employed to analyze retinal organoids and single extracellular vesicles. Single-cell multi-omics sequencing integrates omics information, whereas stereo-sequencing analyzes gene expression and spatiotemporal data simultaneously. This review discusses the protocols of single-cell sequencing for obtaining single cells from retina and accurate sequencing data. It highlights the applications and advancements of single-cell sequencing in the study of normal retinas and the pathological changes associated with diabetic retinopathy. This underscores the potential of these technologies to deepen our understanding of the pathogenesis of diabetic retinopathy that may lead to the introduction of new therapeutic strategies.

Encompassing view of spatial and single-cell RNA sequencing renews the role of the microvasculature in human atherosclerosis

Atherosclerosis is a pervasive contributor to ischemic heart disease and stroke. Despite the advance of lipid-lowering therapies and anti-hypertensive agents, the residual risk of an atherosclerotic event remains high, and developing therapeutic strategies has proven challenging. This is due to the complexity of atherosclerosis with a spatial interplay of multiple cell types within the vascular wall. In this study, we generated an integrative high-resolution map of human atherosclerotic plaques combining single-cell RNA sequencing from multiple studies and spatial transcriptomics data from 12 human specimens with different stages of atherosclerosis. Here we show cell-type-specific and atherosclerosis-specific expression changes and spatially constrained alterations in cell-cell communication. We highlight the possible recruitment of lymphocytes via ACKR1 endothelial cells of the vasa vasorum, the migration of vascular smooth muscle cells toward the lumen by transforming into fibromyocytes and cell-cell communication in the plaque region, indicating an intricate cellular interplay within the adventitia and the subendothelial space in human atherosclerosis.

Inflammation and mechanical force-induced bone remodeling

Periodontitis arises from imbalanced host-microbe interactions, leading to dysbiosis and destructive inflammation. The host's innate and adaptive immune responses produce pro-inflammatory mediators that stimulate destructive events, which cause loss of alveolar bone and connective tissue attachment. There is no consensus on the factors that lead to a conversion from gingivitis to periodontitis, but one possibility is the proximity of the inflammation to the bone, which promotes bone resorption and inhibits subsequent bone formation during coupled bone formation. Conversely, orthodontic tooth movement is triggered by the mechanical force applied to the tooth, resulting in bone resorption on the compression side and new bone formation on the tension side. However, the environment around orthodontic brackets readily retains dental plaque and may contribute to inflammation and bone remodeling. The immune, epithelial, stromal, endothelial and bone cells of the host play an important role in setting the stage for bone remodeling that occurs in both periodontitis and orthodontic tooth movement. Recent advancements in single-cell RNA sequencing have provided new insights into the roles and interactions of different cell types in response to challenges. In this review, we meticulously examine the functions of key cell types such as keratinocytes, leukocytes, stromal cells, osteocytes, osteoblasts, and osteoclasts involved in inflammation- and mechanical force-driven bone remodeling. Moreover, we explore the combined effects of these two conditions: mechanical force-induced bone remodeling combined with periodontal disease (chronic inflammation) and periodontally accelerated osteogenic orthodontics (acute transient inflammation). This comprehensive review enhances our understanding of inflammation- and mechanical force-induced bone remodeling.

Regulation of the blood-brain barrier function by peripheral cues in health and disease

The blood-brain barrier (BBB) is formed by microvascular endothelial cells which are ensembled with pericytes, astrocytes, microglia and neurons in the neurovascular unit (NVU) that is crucial for neuronal function. Given that the NVU and the BBB are highly dynamic and regulated structures, their integrity is continuously challenged by intrinsic and extrinsic factors. Herein, factors from peripheral organs such as gonadal and adrenal hormones may influence vascular function also in CNS endothelial cells in a sex- and age-dependent manner. The communication between the periphery and the CNS likely takes place in specific areas of the brain among which the circumventricular organs have a central position due to their neurosensory or neurosecretory function, owing to physiologically leaky blood vessels. In acute and chronic pathological conditions like liver, kidney, pulmonary disease, toxins and metabolites are generated that reach the brain via the circulation and may directly or indirectly affect BBB functionality via the activation of the immunes system. For example, chronic kidney disease (CKD) currently affects more than 840 million people worldwide and is likely to increase along with western world comorbidities of the cardio-vascular system in continuously ageing societies. Toxins leading to the uremic syndrome, may further lead to neurological complications such as cognitive impairment and uremic encephalopathy. Here we summarize the effects of hormones, toxins and inflammatory reactions on the brain vasculature, highlighting the urgent demand for mechanistically exploring the communication between the periphery and the CNS, focusing on the BBB as a last line of defense for brain protection.

Pericytes Modulate Third-Generation Tyrosine Kinase Inhibitor Sensitivity in EGFR-Mutated Lung Cancer Cells Through IL32-β5-Integrin Paracrine Signaling

EGFR-mutated lung cancer patients sometimes display restricted responses to third-generation tyrosine kinase inhibitors (TKIs), potentially attributable to undervalued input from stromal cells, notably pericytes (PCs). The study shows that PCs isolated from EGFR-mutated patients have a unique secretome profile, notably secreting IL32 and affecting signaling pathways and biological processes linked to TKI sensitivity. Clinical evidence, supported by single-cell RNA sequencing and multiplex immunostaining of tumor tissues, confirms the presence of IL32-expressing pericytes closely interacting with β5-integrin-expressing cancer cells in EGFR-mutated patients, impacting therapeutic response and prognosis. Co-culture and conditioned medium experiments demonstrate that PCs reduce TKI effectiveness in EGFR-mutated cancer cells, a reversible phenomenon through silencing IL32 expression in PCs or depleting the IL32 receptor β5-integrin on cancer cells, thereby restoring cancer cell sensitivity. Mechanistically, it is shown that YY1 signaling upregulates IL32 secretion in PCs, subsequently activating the β5-integrin-Src-Akt pathway in EGFR-mutated cancer cells, contributing to their TKI sensitivity. In animal studies, co-injection of cancer cells with PCs compromises TKI effectiveness, independently of blood vessel functions, while inhibition of β5-integrin restores tumor cell sensitivity. Overall, the findings highlight direct crosstalk between cancer cells and pericytes, impacting TKI sensitivity via IL32-β5-integrin paracrine signaling, proposing an enhanced therapeutic approach for EGFR-mutated patients.

Mechanism and therapeutic targets of circulating immune cells in diabetic retinopathy

Diabetic retinopathy (DR) continues to be the leading cause of preventable vision loss among working-aged adults, marked by immune dysregulation within the retinal microenvironment. Typically, the retina is considered as an immune-privileged organ, where circulating immune cells are restricted from entry under normal conditions. However, during the progression of DR, this immune privilege is compromised as circulating immune cells breach the barrier and infiltrate the retina. Increasing evidence suggests that vascular and neuronal degeneration in DR is largely driven by the infiltration of immune cells, particularly neutrophils, monocyte-derived macrophages, and lymphocytes. This review delves into the mechanisms and therapeutic targets associated with these immune cell populations in DR, offering a promising and innovative approach to managing the disease.

Fibrosis in age-related neovascular macular degeneration in the anti-VEGF era

The natural history of neovascular age-related macular degeneration (nAMD) leads to scarring and loss of vision. Since the advent of anti-VEGF therapies, which are very effective for controlling exudation, large disciform scars are rarely encountered in the clinic. However long term studies show that smaller and less severe fibrotic scars are not uncommon and develop over time despite optimal treatment. This means that additional mechanisms of action may be required to completely address this condition. To permit new treatments, a proper understanding of the clinical impact of fibrosis is required. This review is focused on clinical aspects of fibrosis and summarises recent data on biomarkers, prevalence, causes, consequences, and therapies, highlighting the most important and urgent topics to tackle in order to advance in the treatment of fibrosis.

Pericytes require physiological oxygen tension to maintain phenotypic fidelity

Pericytes function to maintain tissue homeostasis by regulating capillary blood flow and maintaining endothelial barrier function. Pericyte dysfunction is associated with various pathologies and has recently been found to aid cancer progression. Despite having critical functions in health and disease, pericytes remain an understudied population due to a lack of model systems which accurately reflect in vivo biology. In this study we developed a protocol to isolate and culture murine lung, brain, bone, and liver pericytes, that maintains their known phenotypes and functions. We demonstrate that pericytes, being inherently plastic, benefit from controlled oxygen tension culture conditions, aiding their expansion ex vivo. Primary pericytes grown in physiologically relevant oxygen tensions (10% O2 for lung; 5% O2 for brain, bone, and liver) also better retain pericyte phenotypes indicated by stable expression of characteristic transcriptional and protein markers. In functional tube formation assays, pericytes were observed to significantly associate with endothelial junctions. Importantly, we identified growth conditions that limit expression of the plasticity factor Klf4 to prevent spontaneous phenotypic switching in vitro. Additionally, we were able to induce pathological pericyte phenotypic switching in response to metastatic stimuli to accurately recapitulate in vivo biology. Here, we present a robust method for studying pericyte biology in both physiology and disease.

Depicting the cellular complexity of pancreatic adenocarcinoma by Imaging Mass Cytometry: focus on cancer-associated fibroblasts

Introduction

Pancreatic ductal adenocarcinoma (PDAC) represents the complexity of interaction between cancer and cells of the tumor microenvironment (TME). Immune cells affect tumor cell behavior, thus driving cancer progression. Cancer-associated fibroblasts (CAFs) are responsible of the desmoplastic and fibrotic reaction by regulating deposition and remodeling of extracellular matrix (ECM). As tumor-promoting cells abundant in PDAC ECM, CAFs represent promising targets for novel anticancer interventions. However, relevant clinical trials are hampered by the lack of specific markers and elusive differences among CAF subtypes. Indeed, while single-cell transcriptomic analyses have provided important information on the cellular constituents of PDACs and related molecular pathways, studies based on the identification of protein markers in tissues aimed at identifying CAF subtypes and new molecular targets result incomplete.

Methods

Herein, we applied multiplexed Imaging Mass Cytometry (IMC) at single-cell resolution on 8 human PDAC tissues to depict the PDAC composing cells, and profiling immune cells, endothelial cells (ECs), as well as endocrine cells and tumor cells.

Results

We focused on CAFs by characterizing up to 19 clusters distinguished by phenotype, spatiality, and interaction with immune and tumor cells. We report evidence that specific subtypes of CAFs (CAFs 10 and 11) predominantly are enriched at the tumor-stroma interface and closely associated with tumor cells. CAFs expressing different combinations of FAP, podoplanin and cadherin-11, were associated with a higher level of CA19-9. Moreover, we identified specific subsets of FAP+ and podoplanin+/cadherin-11+ CAFs enriched in patients with negative prognosis.

Discussion

The present study provides new general insights into the complexity of the PDAC microenvironment by defining phenotypic heterogeneities and spatial distributions of CAFs, thus suggesting different functions of their subtypes in the PDAC microenvironment.

17β-Estradiol Abrogates TNF-α-Induced Human Brain Vascular Pericyte Migration by Downregulating miR-638 via ER-β

Pericytes (PCs) contribute to brain capillary/BBB integrity and PC migration is a hallmark for brain capillary leakage following pro-inflammatory insults. Estradiol promotes endothelial barrier integrity by inhibiting tumor necrosis factor-alpha (TNF-α)-induced PC migration. However, the underlying mechanisms remain unclear. Since micro-RNAs (miRs) regulate BBB integrity and increases in miR638 and TNF-α occur in pathological events associated with capillary leakage, we hypothesize that TNF-α mediates its capillary disruptive actions via miR638 and that estradiol blocks these actions. Using quantitative reverse transcription PCR, we first assessed the modulatory effects of TNF-α on miR638. The treatment of PCs with TNF-α significantly induced miR638. Moreover, transfection with miR638 mimic induced PC migration, whereas inhibitory miR638 (anti-miR) abrogated the pro-migratory actions of TNF-α, suggesting that TNF-α stimulates PC migration via miR638. At a molecular level, the pro-migratory effects of miR638 involved the phosphorylation of ERK1/2 but not Akt. Interestingly, estradiol downregulated the constitutive and TNF-α-stimulated expression of miR638 and inhibited the TNF-α-induced migration of PCs. In PCs treated with estrogen receptor (ER) ER-α, ER-β, and GPR30 agonists, a significant downregulation in miR638 expression was solely observed in response to DPN, an ER-β agonist. DPN inhibited the pro-migratory effects of TNF-α but not miR638. Additionally, the ectopic expression of miR638 prevented the inhibitory effects of DPN on TNF-α-induced PC migration, suggesting that interference in miR638 formation plays a key role in mediating the inhibitory actions of estradiol/DPN. In conclusion, these findings provide the first evidence that estradiol inhibits TNF-α-induced PC migration by specifically downregulating miR638 via ER-β and may protect the neurovascular unit during injury/stroke via this mechanism.

The Hidden Hand in White Matter: Pericytes and the Puzzle of Demyelination

Disruption of myelin, the fatty sheath-insulating nerve fibers in the white matter, blocks or slows the rapid transmission of electrical signals along nerve cells and contributes to several neurodegenerative diseases such as multiple sclerosis. Traditionally, research has focused on neuronal dysfunction as the primary factor, including autoimmunity, infections, inflammation, and genetic disorders causing demyelination. However, recent insights emphasize the critical role of pericytes, non-neuronal cells that regulate blood flow and maintain the health of blood vessels within white matter. This Perspective explores the principal mechanisms through which pericyte dysfunction contributes to damage and demyelination, including impaired communication with neurons (neurovascular uncoupling), excessive formation of scar tissue (fibrosis), and the infiltration of detrimental substances from the bloodstream. Understanding these mechanisms of pericyte-driven demyelination may lead to the creation of new therapeutic strategies for tackling a range of neurodegenerative conditions.

Targeting the tumour vasculature: from vessel destruction to promotion

As angiogenesis was recognized as a core hallmark of cancer growth and survival, several strategies have been implemented to target the tumour vasculature. Yet to date, attempts have rarely been so diverse, ranging from vessel growth inhibition and destruction to vessel normalization, reprogramming and vessel growth promotion. Some of these strategies, combined with standard of care, have translated into improved cancer therapies, but their successes are constrained to certain cancer types. This Review provides an overview of these vascular targeting approaches and puts them into context based on our subsequent improved understanding of the tumour vasculature as an integral part of the tumour microenvironment with which it is functionally interlinked. This new knowledge has already led to dual targeting of the vascular and immune cell compartments and sets the scene for future investigations of possible alternative approaches that consider the vascular link with other tumour microenvironment components for improved cancer therapy.

Human Endometrial Pericytes: A Comprehensive Overview of Their Physiological Functions and Implications in Uterine Disorders

Pericytes are versatile cells integral to the blood vessel walls of the microcirculation, where they exhibit specific stem cell traits. They are essential in modulating blood flow, ensuring vascular permeability, and maintaining homeostasis and are involved in the tissue repair process. The human endometrium is a unique and complex tissue that serves as a natural scar-free healing model with its cyclical repair and regeneration process every month. The regulation of pericytes has gained increasing attention due to their involvement in various physiological and pathological processes. However, endometrial pericytes are less well studied compared to the pericytes in other organs. This review aims to provide a comprehensive overview of endometrial pericytes, with a focus on elucidating their physiological function and potential implications in uterine disorders.

Multi-omics analysis reveals a pericyte-associated gene expression signature for predicting prognosis and therapeutic responses in solid cancers

The influence of the stroma on cancer progression has been underestimated, particularly the role of vascular pericytes in the tumor microenvironment. Herein, we identified 51 differentially expressed genes in tumor-derived pericytes (TPCs) by analyzing transcriptomic data from TCGA alongside our proteomic data. Using five key TPC-related genes, we constructed a prognostic risk model that accurately predicts prognosis and treatment responses in liver and lung cancers. Enrichment analyses linked these genes to blood vessel remodeling, function, and immune-related pathways. Single-cell RNA sequencing data from the GEO database validated these findings, showing significant upregulation of AKAP12 and RRAS in TPCs. Immunostaining confirmed increased expression of these genes in liver and lung tumors. Depletion of RRAS or AKAP12 in TPCs restored their blood vessel-supporting role. Overall, our findings suggest that TPC-related gene profiles can predict patient outcomes and therapeutic responses in solid cancers, and targeting these profiles could be an improved treatment strategy.

Dynamics of Endothelial Cell Diversity and Plasticity in Health and Disease

Endothelial cells (ECs) are vital structural units of the cardiovascular system possessing two principal distinctive properties: heterogeneity and plasticity. Endothelial heterogeneity is defined by differences in tissue-specific endothelial phenotypes and their high predisposition to modification along the length of the vascular bed. This aspect of heterogeneity is closely associated with plasticity, the ability of ECs to adapt to environmental cues through the mobilization of genetic, molecular, and structural alterations. The specific endothelial cytoarchitectonics facilitate a quick structural cell reorganization and, furthermore, easy adaptation to the extrinsic and intrinsic environmental stimuli, known as the epigenetic landscape. ECs, as universally distributed and ubiquitous cells of the human body, play a role that extends far beyond their structural function in the cardiovascular system. They play a crucial role in terms of barrier function, cell-to-cell communication, and a myriad of physiological and pathologic processes. These include development, ontogenesis, disease initiation, and progression, as well as growth, regeneration, and repair. Despite substantial progress in the understanding of endothelial cell biology, the role of ECs in healthy conditions and pathologies remains a fascinating area of exploration. This review aims to summarize knowledge and concepts in endothelial biology. It focuses on the development and functional characteristics of endothelial cells in health and pathological conditions, with a particular emphasis on endothelial phenotypic and functional heterogeneity.

Pericytes: jack-of-all-trades in cancer-related inflammation

Pericytes, recognized as mural cells, have long been described as components involved in blood vessel formation, playing a mere supporting role for endothelial cells (ECs). Emerging evidence strongly suggests their multifaceted roles in tissues and organs. Indeed, pericytes exhibit a remarkable ability to anticipate endothelial cell behavior and adapt their functions based on the specific cells they interact with. Pericytes can be activated by pro-inflammatory stimuli and crosstalk with immune cells, actively participating in their transmigration into blood vessels. Moreover, they can influence the immune response, often sustaining an immunosuppressive phenotype in most of the cancer types studied. In this review, we concentrate on the intricate crosstalk between pericytes and immune cells in cancer, highlighting the primary evidence regarding pericyte involvement in primary tumor mass dynamics, their contributions to tumor reprogramming for invasion and migration of malignant cells, and their role in the formation of pre-metastatic niches. Finally, we explored recent and emerging pharmacological approaches aimed at vascular normalization, including novel strategies to enhance the efficacy of immunotherapy through combined use with anti-angiogenic drugs.

Single-cell RNA sequencing in exploring the pathogenesis of diabetic retinopathy

Diabetic retinopathy (DR) is a leading cause of irreversible blindness in the working-age populations. Despite decades of research on the pathogenesis of DR for clinical care, a comprehensive understanding of the condition is still lacking due to the intricate cellular diversity and molecular heterogeneity involved. Single-cell RNA sequencing (scRNA-seq) has made the high-throughput molecular profiling of cells across modalities possible which has provided valuable insights into complex biological systems. In this review, we summarise the application of scRNA-seq in investigating the pathogenesis of DR, focusing on four aspects. These include the identification of differentially expressed genes, characterisation of key cell subpopulations and reconstruction of developmental 'trajectories' to unveil their state transition, exploration of complex cell‒cell communication in DR and integration of scRNA-seq with genome-wide association studies to identify cell types that are most closely related to DR risk genetic loci. Finally, we discuss the future challenges and expectations associated with studying DR using scRNA-seq. We anticipate that scRNA-seq will facilitate the discovery of mechanisms and new treatment targets in the clinical care landscape for patients with DR. KEY POINTS: Progress in scRNA-seq for diabetic retinopathy (DR) research includes studies on DR patients, non-human primates, and the prevalent mouse models. scRNA-seq facilitates the identification of differentially expressed genes, pivotal cell subpopulations, and complex cell-cell interactions in DR at single-cell level. Future scRNA-seq applications in DR should target specific patient subsets and integrate with single-cell and spatial multi-omics approaches.

Assessment of cerebrovascular alterations induced by inflammatory response and oxidative-nitrative stress after traumatic intracranial hypertension and a potential mitigation strategy

The rapid perfusion of cerebral arteries leads to a significant increase in intracranial blood volume, exposing patients with traumatic brain injury to the risk of diffuse brain swelling or malignant brain herniation during decompressive craniectomy. The microcirculation and venous system are also involved in this process, but the precise mechanisms remain unclear. A physiological model of extremely high intracranial pressure was created in rats. This development triggered the TNF-α/NF-κB/iNOS axis in microglia, and released many inflammatory factors and reactive oxygen species/reactive nitrogen species, generating an excessive amount of peroxynitrite. Subsequently, the capillary wall cells especially pericytes exhibited severe degeneration and injury, the blood-brain barrier was disrupted, and a large number of blood cells were deposited within the microcirculation, resulting in a significant delay in the recovery of the microcirculation and venous blood flow compared to arterial flow, and this still persisted after decompressive craniectomy. Infliximab is a monoclonal antibody bound to TNF-α that effectively reduces the activity of TNF-α/NF-κB/iNOS axis. Treatment with Infliximab resulted in downregulation of inflammatory and oxidative-nitrative stress related factors, attenuation of capillary wall cells injury, and relative reduction of capillary hemostasis. These improved the delay in recovery of microcirculation and venous blood flow.

Signaling Role of Pericytes in Vascular Health and Tissue Homeostasis

Pericytes are multipotent cells embedded within the vascular system, primarily surrounding capillaries and microvessels where they closely interact with endothelial cells. These cells are known for their intriguing properties due to their heterogeneity in tissue distribution, origin, and multifunctional capabilities. Specifically, pericytes are essential in regulating blood flow, promoting angiogenesis, and supporting tissue homeostasis and regeneration. These multifaceted roles draw on pericytes' remarkable ability to respond to biochemical cues, interact with neighboring cells, and adapt to changing environmental conditions. This review aims to summarize existing knowledge on pericytes, emphasizing their versatility and involvement in vascular integrity and tissue health. In particular, a comprehensive view of the major signaling pathways, such as PDGFβ/ PDGFRβ, TGF-β, FOXO and VEGF, along with their downstream targets, which coordinate the behavior of pericytes in preserving vascular integrity and promoting tissue regeneration, will be discussed. In this light, a deeper understanding of the complex signaling networks defining the phenotype of pericytes in healthy tissues is crucial for the development of targeted therapies in vascular and degenerative diseases.

Dynamic changes in structure and function of brain mural cells around chronically implanted microelectrodes

Integration of neural interfaces with minimal tissue disruption in the brain is ideal to develop robust tools that can address essential neuroscience questions and combat neurological disorders. However, implantation of intracortical devices provokes severe tissue inflammation within the brain, which requires a high metabolic demand to support a complex series of cellular events mediating tissue degeneration and wound healing. Pericytes, peri-vascular cells involved in blood-brain barrier maintenance, vascular permeability, waste clearance, and angiogenesis, have recently been implicated as potential perpetuators of neurodegeneration in brain injury and disease. While the intimate relationship between pericytes and the cortical microvasculature have been explored in other disease states, their behavior following microelectrode implantation, which is responsible for direct blood vessel disruption and dysfunction, is currently unknown. Using two-photon microscopy we observed dynamic changes in the structure and function of pericytes during implantation of a microelectrode array over a 4-week implantation period. Pericytes respond to electrode insertion through transient increases in intracellular calcium and underlying constriction of capillary vessels. Within days following the initial insertion, we observed an influx of new, proliferating pericytes which contribute to new blood vessel formation. Additionally, we discovered a potentially novel population of reactive immune cells in close proximity to the electrode-tissue interface actively engaging in encapsulation of the microelectrode array. Finally, we determined that intracellular pericyte calcium can be modulated by intracortical microstimulation in an amplitude- and frequency-dependent manner. This study provides a new perspective on the complex biological sequelae occurring the electrode-tissue interface and will foster new avenues of potential research consideration and lead to development of more advanced therapeutic interventions towards improving the biocompatibility of neural electrode technology.

Exploring the diversity of cancer-associated fibroblasts: insights into mechanisms of drug resistance

Introduction: Among the various stromal cell types within the tumor microenvironment, cancer-associated fibroblasts (CAFs) emerge as the predominant constituent, exhibiting a diverse array of oncogenic functions not intrinsic to normal fibroblasts. Their involvement spans across all stages of tumorigenesis, encompassing initiation, progression, and metastasis. Current understanding posits the coexistence of distinct subpopulations of CAFs within the tumor microenvironment across a spectrum of solid tumors, showcasing both pro- and antitumor activities. Recent advancements in single-cell transcriptomics have revolutionized our ability to meticulously dissect the heterogeneity inherent to CAF populations. Furthermore, accumulating evidence underscores the pivotal role of CAFs in conferring therapeutic resistance to tumors against various drug modalities. Consequently, efforts are underway to develop pharmacological agents specifically targeting CAFs. Methods: This review embarks on a comprehensive analysis, consolidating data from 36 independent single-cell RNA sequencing investigations spanning 17 distinct human malignant tumor types. Results: Our exploration centers on elucidating CAF population markers, discerning their prognostic relevance, delineating their functional contributions, and elucidating the underlying mechanisms orchestrating chemoresistance. Discussion: Finally, we deliberate on the therapeutic potential of harnessing CAFs as promising targets for intervention strategies in clinical oncology.

Applications of Tissue Clearing in Central and Peripheral Nerves

The techniques of tissue clearing have been proposed and applied in anatomical and biomedical research since the 19th century. As we all know, the original study of the nervous system relied on serial ultrathin sections and stereoscopic techniques. The 3D visualization of the nervous system was established by software splicing and reconstruction. With the development of science and technology, microscope equipment had constantly been upgraded. Despite the great progress that has been made in this field, the workload is too complex, and it needs high technical requirements. Abundant mistakes due to manual sections were inescapable and structural integrity remained questionable. According to the classification of tissue transparency methods, we introduced the latest application of transparency methods in central and peripheral nerve research from optical imaging, molecular markers and data analysis. This review summarizes the application of transparent technology in neural pathways. We hope to provide some inspiration for the continuous optimization of tissue clearing methods.

Role of endothelial PDGFB in arterio-venous malformations pathogenesis

Arterial-venous malformations (AVMs) are direct connections between arteries and veins without an intervening capillary bed. Either familial inherited or sporadically occurring, localized pericytes (PCs) drop is among the AVMs' hallmarks. Whether impaired PC coverage triggers AVMs or it is a secondary event is unclear. Here we evaluated the role of the master regulator of PC recruitment, Platelet derived growth factor B (PDGFB) in AVM pathogenesis. Using tamoxifen-inducible deletion of Pdgfb in endothelial cells (ECs), we show that disruption of EC Pdgfb-mediated PC recruitment and maintenance leads to capillary enlargement and organotypic AVM-like structures. These vascular lesions contain non-proliferative hyperplastic, hypertrophic and miss-oriented capillary ECs with an altered capillary EC fate identity. Mechanistically, we propose that PDGFB maintains capillary EC size and caliber to limit hemodynamic changes, thus restricting expression of Krüppel like factor 4 and activation of Bone morphogenic protein, Transforming growth factor β and NOTCH signaling in ECs. Furthermore, our study emphasizes that inducing or activating PDGFB signaling may be a viable therapeutic approach for treating vascular malformations.

Non-gastrointestinal stromal tumor, mesenchymal neoplasms of the gastrointestinal tract: a review of tumor genetics, pathology, and cross-sectional imaging findings

There is a diverse group of non-gastrointestinal stromal tumor (GIST), mesenchymal neoplasms of the gastrointestinal (GI) tract that demonstrate characteristic pathology and histogenesis as well as variable imaging findings and biological behavior. Recent advancements in tumor genetics have unveiled specific abnormalities associated with certain tumors, influencing their molecular pathogenesis, biology, response to treatment, and prognosis. Notably, giant fibrovascular polyps of the esophagus, identified through MDM2 gene amplifications, are now classified as liposarcomas. Some tumors exhibit distinctive patterns of disease distribution. Glomus tumors and plexiform fibromyxomas exhibit a pronounced affinity for the gastric antrum. In contrast, smooth muscle tumors within the GI tract are predominantly found in the esophagus and colorectum, surpassing the incidence of GISTs in these locations. Surgical resection suffices for symptomatic benign tumors; multimodality treatment may be necessary for frank sarcomas. This article aims to elucidate the cross-sectional imaging findings associated with a wide spectrum of these tumors, providing insights that align with their histopathological features.

The disruptive role of LRG1 on the vasculature and perivascular microenvironment

The establishment of new blood vessels, and their subsequent stabilization, is a critical process that facilitates tissue growth and organ development. Once established, vessels need to diversify to meet the specific needs of the local tissue and to maintain homeostasis. These processes are tightly regulated and fundamental to normal vessel and tissue function. The mechanisms that orchestrate angiogenesis and vessel maturation have been widely studied, with signaling crosstalk between endothelium and perivascular cells being identified as an essential component. In disease, however, new vessels develop abnormally, and existing vessels lose their specialization and function, which invariably contributes to disease progression. Despite considerable research into the vasculopathic mechanisms in disease, our knowledge remains incomplete. Accordingly, the identification of angiocrine and angiopathic molecules secreted by cells within the vascular microenvironment, and their effect on vessel behaviour, remains a major research objective. Over the last decade the secreted glycoprotein leucine-rich α-2 glycoprotein 1 (LRG1), has emerged as a significant vasculopathic molecule, stimulating defective angiogenesis, and destabilizing the existing vasculature mainly, but not uniquely, by altering both canonical and non-canonical TGF-β signaling in a highly cell and context dependent manner. Whilst LRG1 does not possess any overt homeostatic role in vessel development and maintenance, growing evidence provides a compelling case for LRG1 playing a pleiotropic role in disrupting the vasculature in many disease settings. Thus, LRG1 has now been reported to damage vessels in various disorders including cancer, diabetes, chronic kidney disease, ocular disease, and lung disease and the signaling processes that drive this dysfunction are being defined. Moreover, therapeutic targeting of LRG1 has been widely proposed to re-establish a quiescent endothelium and normalized vasculature. In this review, we consider the current status of our understanding of the role of LRG1 in vascular pathology, and its potential as a therapeutic target.

PTEN: an emerging target in rheumatoid arthritis?

Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a critical tumor suppressor protein that regulates various biological processes such as cell proliferation, apoptosis, and inflammatory responses by controlling the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (PI3K/AKT) signaling pathway. PTEN plays a crucial role in the pathogenesis of rheumatoid arthritis (RA). Loss of PTEN may contribute to survival, proliferation, and pro-inflammatory cytokine release of fibroblast-like synoviocytes (FLS). Also, persistent PI3K signaling increases myeloid cells' osteoclastic potential, enhancing localized bone destruction. Recent studies have shown that the expression of PTEN protein in the synovial lining of RA patients with aggressive FLS is minimal. Experimental upregulation of PTEN protein expression could reduce the damage caused by RA. Nonetheless, a complete comprehension of aberrant PTEN drives RA progression and its interactions with other crucial molecules remains elusive. This review is dedicated to promoting a thorough understanding of the signaling mechanisms of aberrant PTEN in RA and aims to furnish pertinent theoretical support for forthcoming endeavors in both basic and clinical research within this domain.

The role of pericyte in ocular vascular diseases

Pericytes are located in the stromal membrane of the capillary outer wall and contain endothelial cells (ECs). They are pivotal in regulating blood flow, enhancing vascular stability, and maintaining the integrity of the blood-retina barrier (BRB)/blood-brain barrier (BBB). The pluripotency of pericytes allows them to differentiate into various cell types, highlighting their significance in vascular disease pathogenesis, as demonstrated by previous studies. This potential enables pericytes to be a potential biomarker for the diagnosis and a target for treatment of vascular disorders. The retina, an essential part of the eyeball, is an extension of cerebral tissue with a transparent refractive medium. It offers a unique window for assessing systemic microvascular lesions. Routine fundus examination is necessary for patients with diabetes and hypertension. Manifestations, such as retinal artery tortuosity, dilation, stenosis, and abnormal arteriovenous anastomosis, serve as typical hallmarks of retinal vasculopathy. Therefore, studies of ocular vascular diseases significantly facilitate the exploration of systemic vascular diseases.

Role of autophagy in angiogenic potential of vascular pericytes

The vasculature system is composed of a multiplicity of juxtaposed cells to generate a functional biological barrier between the blood and tissues. On the luminal surface of blood vessels, endothelial cells (ECs) are in close contact with circulating cells while supporting basal lamina and pericytes wrap the abluminal surface. Thus, the reciprocal interaction of pericytes with ECs is a vital element in the physiological activity of the vascular system. Several reports have indicated that the occurrence of pericyte dysfunction under ischemic and degenerative conditions results in varied micro and macro-vascular complications. Emerging evidence points to the fact that autophagy, a conserved self-digestive cell machinery, can regulate the activity of several cells like pericytes in response to various stresses and pathological conditions. Here, we aim to highlight the role of autophagic response in pericyte activity and angiogenesis potential following different pathological conditions.

Age and vascular aging: an unexplored frontier

Vascular age is an emerging field in cardiovascular risk assessment. This concept includes multifactorial changes in the arterial wall, with arterial stiffness as its most relevant manifestation, leading to increased arterial pressure and pulsatile flow in the organs. Today, the approved test for measuring vascular age is pulse wave velocity, which has been proven to predict cardiovascular events. Furthermore, vascular phenotypes, such as early vascular aging and "SUPERNOVA," representing phenotypic extremes of vascular aging, have been found. The identification of these phenotypes opens a new field of study in cardiovascular physiology. Lifestyle interventions and pharmacological therapy have positively affected vascular health, reducing arterial stiffness. This review aims to define the concepts related to vascular age, pathophysiology, measurement methods, clinical signs and symptoms, and treatment.

The Role and Therapeutic Implications of Inflammation in the Pathogenesis of Brain Arteriovenous Malformations

Brain arteriovenous malformations (bAVMs) are focal vascular lesions composed of abnormal vascular channels without an intervening capillary network. As a result, high-pressure arterial blood shunts directly into the venous outflow system. These high-flow, low-resistance shunts are composed of dilated, tortuous, and fragile vessels, which are prone to rupture. BAVMs are a leading cause of hemorrhagic stroke in children and young adults. Current treatments for bAVMs are limited to surgery, embolization, and radiosurgery, although even these options are not viable for ~20% of AVM patients due to excessive risk. Critically, inflammation has been suggested to contribute to lesion progression. Here we summarize the current literature discussing the role of the immune system in bAVM pathogenesis and lesion progression, as well as the potential for targeting inflammation to prevent bAVM rupture and intracranial hemorrhage. We conclude by proposing that a dysfunctional endothelium, which harbors the somatic mutations that have been shown to give rise to sporadic bAVMs, may drive disease development and progression by altering the immune status of the brain.