Laminin isoforms in endothelial and perivascular basement membranes

Brain vascular basement membrane: comparison of human and mouse brain at the transcriptomic and proteomic levels

The cerebrovascular basement membrane (BM) is a key component of the blood-brain barrier (BBB). The BM provides structural support for brain microvascular endothelial cells and the supporting cells of the neurovascular unit, and facilitates cell signaling through adhesion receptors, regulates the concentration of soluble factors, and serves as an additional barrier for transport. However, our understanding of the composition of BM remains incomplete. Here we analyze recent proteomic and genomic data to assess the composition of BM in human and mouse brain, and in tissue-engineered BBB models. All data sets confirm that the main components of brain BM are collagen IV a1/2, laminin, along with agrin, perlecan, and nidogen. Transcriptomic data from human BMECs suggests that the main laminin isoform is Laminin 321, while transcriptomic data from mice and proteomic data from mice and humans suggest that Laminin 521 is the predominant isoform. Transcriptomic data from iBMECs suggest that Laminin 511 is the predominant isoform. The supporting molecules agrin, perlecan, and nidogen were detected at significant levels in all studies, although only nidogen 1 was detected in the human transcriptomic data sets. No significant differences in human BM composition were observed in BMECs along the arterio-venous axis, or in comparison of healthy and AD brains.

Proportions of Basement Membrane Proteins in Cerebrovascular Smooth Muscle Cells After Exposure to Hypercapnia and Amyloid Beta

Vascular basement membranes (BMs), composed of laminins, collagen IV, fibronectin, and perlecan, are secreted by endothelial cells, pericytes, smooth muscle cells (SMCs), and astrocytes. In the brain, amyloid beta (Aβ) is eliminated along cerebrovascular BMs of capillaries and arteries as intramural periarterial drainage (IPAD). Ageing modifies vascular BMs, impairing IPAD and leading to Aβ deposition as cerebral amyloid angiopathy. To better understand the molecular determinants of IPAD in ageing, we quantified the relative abundance of BMs secreted by human-derived cerebral endothelial cells, pericytes, brain vascular SMCs, and astrocytes in vitro. We then assessed BM protein levels in SMCs under hypercapnia (8% CO2) as a model of vascular ageing, with and without Aβ exposure. Of the four cell types, we found SMCs secreted the highest levels of fibronectin, laminin, and perlecan, whilst pericytes secreted the highest levels of collagen IV. Hypercapnia increased the expression of collagen IV and fibronectin in SMCs but decreased the expression of laminin. The expression of perlecan increased under hypercapnia, but only in the presence of Aβ. This work highlights the varying compositions of vascular BMs and the dynamic differential responses of SMCs to Aβ and hypercapnia, helping to elucidate the age-related changes that impair IPAD in cerebral vessels.

Novel Plasma Biomarkers for Alzheimer's Disease: Insights from Organotypic Brain Slice and Microcontact Printing Techniques

BACKGROUND

Alzheimer's disease (AD) is a severe neurodegenerative disorder characterized by beta-amyloid plaques and tau neurofibrillary tangles. The diagnosis of AD is complex, with the analysis of beta-amyloid and tau in cerebrospinal fluid being a well-established diagnostic approach. However, currently no blood biomarkers have been identified or validated for clinical use. In the present study, we will identify novel plasma biomarkers for AD using our well-established organotypic mouse brain slice model connected to microcontact prints. We hypothesize that AD plasma contains factors that affect endothelial cell migration and new vessel formation.

METHODS

In the present study, plasma from human patients is microcontact printed and connected to mouse brain slices. After 4 weeks in culture, laminin+ and lectin+ endothelial cells (ECs) and vessels are analyzed by immunostaining techniques. The most promising samples were processed by differential mass spectrometry.

RESULTS

Our data show that AD plasma significantly increased the migration length of laminin+ and lectin+ ECs along the microcontact prints. Using differential mass spectrometry, we could identify three potential biomarkers: C-reactive protein, basigin, and trem-like transcript 1 protein.

CONCLUSION

Here we show that brain slices connected to human plasma prints allow the identification of novel human AD biomarkers with subsequent mass spectrometry. This technique represents a novel and innovative approach to translate research findings from mouse models to human applications.

More severe vascular remodeling in deep brain regions caused by hemodynamic differences is a potential mechanism of hypertensive cerebral small vessel disease

In hypertension-associated arteriolosclerosis cerebral small vessel disease (CSVD), various studies have shown that MRI-detected lesions-such as lacunes, white matter hyperintensities, enlarged perivascular spaces, and cerebral microbleeds-are more prevalent in deep brain regions (DBR) than in the cortex. However, the underlying mechanisms remain poorly understood. We propose that differential vascular remodeling between DBR small vessels and superficial cortical branches contributes to this heterogeneity. Using a stroke-prone renovascular hypertensive rat (RHRsp) model, we observed pronounced changes in vessel density, diameter, extracellular matrix deposition, and smooth muscle cell alterations in DBR small arteries compared to that of the cortex. These findings were further confirmed in human brain tissue of our study. Additionally, our mathematical modeling indicated greater hemodynamic alterations in DBR vessels, with increased shear and circumferential stress under hypertension conditions. Overall, our study highlights more severe vascular remodeling and hemodynamic changes in the deep brain regions, where CSVD-associated MRI lesions are frequently detected.

The Mycobacterium ulcerans toxin mycolactone causes destructive Sec61-dependent loss of the endothelial glycocalyx and vessel basement membrane to drive skin necrosis

The drivers of tissue necrosis in Mycobacterium ulcerans infection (Buruli ulcer disease) have historically been ascribed solely to the directly cytotoxic action of the diffusible exotoxin, mycolactone. However, its role in the clinically evident vascular component of disease aetiology remains poorly explained. We have now dissected mycolactone's effects on human primary vascular endothelial cells in vitro. We show that mycolactone-induced changes in endothelial morphology, adhesion, migration, and permeability are dependent on its action at the Sec61 translocon. Unbiased quantitative proteomics identified a profound effect on proteoglycans, driven by rapid loss of type II transmembrane proteins of the Golgi, including enzymes required for glycosaminoglycan (GAG) synthesis, combined with a reduction in the core proteins themselves. Loss of the glycocalyx is likely to be of particular mechanistic importance, since knockdown of galactosyltransferase II (beta-1,3-galactotransferase 6; B3GALT6), the GAG linker-building enzyme, phenocopied the permeability and phenotypic changes induced by mycolactone. Additionally, mycolactone depleted many secreted basement membrane components and microvascular basement membranes were disrupted in vivo during M. ulcerans infection in the mouse model. Remarkably, exogenous addition of laminin-511 reduced endothelial cell rounding, restored cell attachment and reversed the defective migration caused by mycolactone. Hence supplementing mycolactone-depleted extracellular matrix may be a future therapeutic avenue, to improve wound healing rates.

The role of laminins in cancer pathobiology: a comprehensive review

Laminins (LMs) are a family of heterotrimeric glycoproteins that form the structural foundation of basement membranes (BM). By acting as molecular bridges between cells and the extracellular matrix (ECM) through integrins and other surface receptors, they regulate key cellular signals that influence cell behavior and tissue architecture. Despite their physiological importance, our understanding of the role of LMs in cancer pathobiology remains fragmented. In this article, we review the diverse functions of LMs in promoting cancer cell proliferation, adhesion, and migration-critical steps in cancer metastasis. Beyond their direct effects on tumor cells, LMs influence stromal interactions and modulate tumor microenvironment dynamics, affecting processes such as angiogenesis, immune cell infiltration, cancer-associated fibroblast activation, and immune evasion. Understanding the complex roles of LMs in cancer biology, as well as their differential expression patterns in malignancies, could provide new diagnostic tools for predicting disease outcomes and pave the way for innovative therapeutic strategies, such as targeting LM-receptor interactions or modulating ECM dynamics to impede tumor growth and metastasis.

Fully biologic endothelialized-tissue-engineered vascular conduits provide antithrombotic function and graft patency

Tissue-engineered vascular conduits (TEVCs), often made by seeding autologous bone marrow cells onto biodegradable polymeric scaffolds, hold promise toward treating single-ventricle congenital heart defects (SVCHDs). However, the clinical adoption of TEVCs has been hindered by a high incidence of graft stenosis in prior TEVC clinical trials. Herein, we developed endothelialized TEVCs by coating the luminal surface of decellularized human umbilical arteries with human induced pluripotent stem cell (hiPSC)-derived endothelial cells (ECs), followed by shear stress training, in flow bioreactors. These TEVCs provided immediate antithrombotic function and expedited host EC recruitment after implantation as interposition inferior vena cava grafts in nude rats. Graft patency was maintained with no thrombus formation, followed by complete replacement of host ECs. Our study lays the foundation for future production of fully biologic TEVCs composed of hiPSC-derived ECs as an innovative therapy for SVCHDs.

Basement membranes' role in immune cell recruitment to the central nervous system

Basement membranes form part of the extracellular matrix (ECM), which is the structural basis for all tissue. Basement membranes are cell-adherent sheets found between cells and vascular endothelia, including those of the central nervous system (CNS). There is exceptional regional specialisation of these structures, both in tissue organisation and regulation of tissue-specific cellular processes. Due to their location, basement membranes perform a key role in immune cell trafficking and therefore are important in inflammatory processes causing or resulting from CNS disease and injury. This review will describe basement membranes in detail, with special focus on the brain. We will cover how genetic changes drive brain pathology, describe basement membranes' role in immune cell recruitment and how they respond to various brain diseases. Understanding how basement membranes form the junction between the immune and central nervous systems will be a major advance in understanding brain disease.

Vascular Basement Membrane Fragmentation in Keloids and the Expression of Key Basement Membrane Component Genes

Background

Keloids are growing scars that arise from injury to the reticular dermis and subsequent chronic local inflammation. The latter may be promoted by vascular hyperpermeability, which permits the ingress of chronic inflammatory cells/factors. Cutaneous capillaries consist of endothelial cells that generate, and are anchored by, a vascular basement membrane (VBM). Because VBM blocks immune cells/factors ingress, we investigated whether keloids are associated with altered VBM structure and/or VBM component expression by local endothelial cells.

Methods

In total, 54 keloid (n = 27) and adjacent normal skin (n = 27) samples from 14 patients underwent transmission electron microscopy (TEM). Cross-sections of whole capillaries were identified. VBM thickness, continuity, and the number of layers in keloid and normal skin tissues were quantified. The differential expression of 222 previously reported VBM component genes in keloid and normal skin endothelial cells was analyzed using the GSE121618-microarray dataset.

Results

TEM images showed that keloid VBMs were significantly thinner than adjacent skin VBMs (0.053 versus 0.078 nm; P < 0.001). They were also greatly fragmented (continuity was 46% versus 85% in normal skin; P < 0.001) and had fewer (1.2 versus 2.4) layers (P < 0.001). Keloidal endothelial cells demonstrated downregulation of 22 genes, including papilin, laminin-α5, and laminin-α2, and upregulation of 28 genes, including laminin-β1, laminin-β2, laminin-γ1, and laminin-γ2.

Conclusions

VBMs are greatly fragmented in keloids. These changes support the notion that keloids are initiated/promoted, at least partly, by vascular hyperpermeability.

Familial osteochondrodysplastic and cardiomyopathic syndrome in Chianina cattle

BACKGROUND

Skeletal dysplasia encompasses a heterogeneous group of genetic disorders characterized by an abnormal development of bones, joints, and cartilage. Two Chianina half-sibling calves from consanguineous mating with congenital skeletal malformations and cardiac abnormalities were identified.

HYPOTHESIS/OBJECTIVES

To characterize the disease phenotype, to evaluate its genetic cause, and to determine the prevalence of the deleterious alleles in the Chianina population.

ANIMALS

Two affected calves, their parents and 332 Chianina bulls.

METHODS

The affected animals underwent clinicopathological investigation. Whole-genome sequencing trio-approach and PCR-based assessment of the frequency of TDP-glucose 4,6-dehydratase (TGDS) and laminin subunit alpha 4 (LAMA4) alleles were performed.

RESULTS

The cases presented with retarded growth, poor nutritional status associated with muscular atrophy and angular deformities of the hindlimbs. Radiologic examination identified generalized osteopenia and shortening of the limb long bones. Necropsy showed osteochondrodysplastic limbs and dilatation of the heart right ventricle. On histological examination, the physeal cartilages were characterized by multifocal mild to moderate loss of the normal columnar arrangement of chondrocytes. Osteopenia also was observed. Genetic analysis identified a missense variant in TGDS and a splice-site variant in LAMA4, both of which were homozygous in the 2 cases. Parents were heterozygous and allele frequency in the Chianina population for the TGDS variant was 5% and for the LAMA4 variant was 2%.

CONCLUSIONS AND CLINICAL IMPORTANCE

Genetic findings identified 2 potentially pathogenic alleles in TGDS and LAMA4, but no clear mode of inheritance could be determined.

Biomechanical properties of laminins and their impact on cancer progression

Laminins (LMs) constitute a family of heterotrimeric glycoproteins essential for the formation of basement membranes (BM). They act as molecular bridges between cells and the extracellular matrix (ECM), thereby transmitting signals influencing cell behavior and tissue organization. In the realm of cancer pathobiology, LMs regulate key processes such as migration, differentiation, or fibrosis. This review critically examines the multifaceted impact of LMs on tumor progression, with a particular focus on the isoform-specific structure-function relationships, and how this structural diversity contributes to the biomechanical properties of BMs. LM interactions with integrin and non-integrin cell surface receptors, as well as with other ECM proteins, modify the response of cancer cells to the ECM stiffness, ultimately influencing the capacity of malignant cells to breach the BM, a limiting step in metastatic dissemination. Comprehension of the mechanisms underlying LM-driven tumor biomechanics holds potential for better understand cancer pathobiology and design new targeted therapeutic strategies.

The Effects of Biomimetic Surface Topography on Vascular Cells: Implications for Vascular Conduits

Cardiovascular diseases (CVDs) are the leading cause of mortality worldwide and represent a pressing clinical need. Vascular occlusions are the predominant cause of CVD and necessitate surgical interventions such as bypass graft surgery to replace the damaged or obstructed blood vessel with a synthetic conduit. Synthetic small-diameter vascular grafts (sSDVGs) are desired to bypass blood vessels with an inner diameter <6 mm yet have limited use due to unacceptable patency rates. The incorporation of biophysical cues such as topography onto the sSDVG biointerface can be used to mimic the cellular microenvironment and improve outcomes. In this review, the utility of surface topography in sSDVG design is discussed. First, the primary challenges that sSDVGs face and the rationale for utilizing biomimetic topography are introduced. The current literature surrounding the effects of topographical cues on vascular cell behavior in vitro is reviewed, providing insight into which features are optimal for application in sSDVGs. The results of studies that have utilized topographically-enhanced sSDVGs in vivo are evaluated. Current challenges and barriers to clinical translation are discussed. Based on the wealth of evidence detailed here, substrate topography offers enormous potential to improve the outcome of sSDVGs and provide therapeutic solutions for CVDs.

Mycolactone causes destructive Sec61-dependent loss of the endothelial glycocalyx and vessel basement membrane: a new indirect mechanism driving tissue necrosis in Mycobacterium ulcerans infection

The drivers of tissue necrosis in Mycobacterium ulcerans infection (Buruli ulcer disease) have historically been ascribed solely to the directly cytotoxic action of the diffusible exotoxin, mycolactone. However, its role in the clinically-evident vascular component of disease aetiology remains poorly explained. We have now dissected mycolactone's effects on primary vascular endothelial cells in vitro and in vivo. We show that mycolactone-induced changes in endothelial morphology, adhesion, migration, and permeability are dependent on its action at the Sec61 translocon. Unbiased quantitative proteomics identified a profound effect on proteoglycans, driven by rapid loss of type II transmembrane proteins of the Golgi, including enzymes required for glycosaminoglycan (GAG) synthesis, combined with a reduction in the core proteins themselves. Loss of the glycocalyx is likely to be of particular mechanistic importance, since knockdown of galactosyltransferase II (beta-1,3-galactotransferase 6; B3GALT6), the GAG linker-building enzyme, phenocopied the permeability and phenotypic changes induced by mycolactone. Additionally, mycolactone depleted many secreted basement membrane components and microvascular basement membranes were disrupted in vivo. Remarkably, exogenous addition of laminin-511 reduced endothelial cell rounding, restored cell attachment and reversed the defective migration caused by mycolactone. Hence supplementing mycolactone-depleted extracellular matrix may be a future therapeutic avenue, to improve wound healing rates.

Assessing Cerebral Microvascular Volumetric Pulsatility with High-Resolution 4D CBV MRI at 7T

Arterial pulsation is crucial for promoting fluid circulation and for influencing neuronal activity. Previous studies assessed the pulsatility index based on blood flow velocity pulsatility in relatively large cerebral arteries of human. Here, we introduce a novel method to quantify the volumetric pulsatility of cerebral microvasculature across cortical layers and in white matter (WM), using high-resolution 4D vascular space occupancy (VASO) MRI with simultaneous recording of pulse signals at 7T. Microvascular volumetric pulsatility index (mvPI) and cerebral blood volume (CBV) changes across cardiac cycles are assessed through retrospective sorting of VASO signals into cardiac phases and estimating mean CBV in resting state (CBV0) by arterial spin labeling (ASL) MRI at 7T. Using data from 11 young (28.4±5.8 years) and 7 older (61.3±6.2 years) healthy participants, we investigated the aging effect on mvPI and compared microvascular pulsatility with large arterial pulsatility assessed by 4D-flow MRI. We observed the highest mvPI in the cerebrospinal fluid (CSF) on the cortical surface (0.19±0.06), which decreased towards the cortical layers as well as in larger arteries. In the deep WM, a significantly increased mvPI (p = 0.029) was observed in the older participants compared to younger ones. Additionally, mvPI in deep WM is significantly associated with the velocity pulsatility index (vePI) of large arteries (r = 0.5997, p = 0.0181). We further performed test-retest scans, non-parametric reliability test and simulations to demonstrate the reproducibility and accuracy of our method. To the best of our knowledge, our method offers the first in vivo measurement of microvascular volumetric pulsatility in human brain which has implications for cerebral microvascular health and its relationship research with glymphatic system, aging and neurodegenerative diseases.

Methylome analysis of endothelial cells suggests new insights on sporadic brain arteriovenous malformation

Arteriovenous malformation of the brain (bAVM) is a vascular phenotype related to brain defective angiogenesis. Involved vessels show impaired expression of vascular differentiation markers resulting in the arteriolar to venule direct shunt. In order to clarify aberrant gene expression occurring in bAVM, here we describe results obtained by methylome analysis performed on endothelial cells (ECs) isolated from bAVM specimens, compared to human cerebral microvascular ECs. Results were validated by quantitative methylation-specific PCR and quantitative realtime-PCR. Differential methylation events occur in genes already linked to bAVM onset, as RBPJ and KRAS. However, among differentially methylated genes, we identified EPHB1 and several other loci involved in EC adhesion as well as in EC/vascular smooth muscle cell (VSMC) crosstalk, suggesting that only endothelial dysfunction might not be sufficient to trigger the bAVM phenotype. Moreover, aberrant methylation pattern was reported for many lncRNA genes targeting transcription factors expressed during neurovascular development. Among these, the YBX1 that was recently shown to target the arteridin coding gene. Finally, in addition to the conventional CpG methylation, we further considered the role of impaired CHG methylation, mainly occurring in brain at embryo stage. We showed as differentially CHG methylated genes are clustered in pathways related to EC homeostasis, as well as to VSMC-EC crosstalk, suggesting as impairment of this interaction plays a prominent role in loss of vascular differentiation, in bAVM phenotype.

TNF Induces Laminin-332-Encoding Genes in Endothelial Cells and Laminin-332 Promotes an Atherogenic Endothelial Phenotype

Laminins are essential components of the basement membranes, expressed in a tissue- and cell-specific manner under physiological conditions. During inflammatory circumstances, such as atherosclerosis, alterations in laminin composition within vessels have been observed. Our study aimed to assess the influence of tumor necrosis factor-alpha (TNF), a proinflammatory cytokine abundantly found in atherosclerotic lesions, on endothelial laminin gene expression and the effects of laminin-332 (LN332) on endothelial cells' behavior. We also evaluated the expression of LN332-encoding genes in human carotid atherosclerotic plaques. Our findings demonstrate that TNF induces upregulation of LAMB3 and LAMC2, which, along with LAMA3, encode the LN332 isoform. Endothelial cells cultured on recombinant LN332 exhibit decreased claudin-5 expression and display a loosely connected phenotype, with an elevated expression of chemokines and leukocyte adhesion molecules, enhancing their attractiveness and adhesion to leukocytes in vitro. Furthermore, LAMB3 and LAMC2 are upregulated in human carotid plaques and show a positive correlation with TNF expression. In summary, TNF stimulates the expression of LN332-encoding genes in human endothelial cells and LN332 promotes an endothelial phenotype characterized by compromised junctional integrity and increased leukocyte interaction. These findings highlight the importance of basement membrane proteins for endothelial integrity and the potential role of LN332 in atherosclerosis.

Collagen concentration regulates neutrophil extravasation and migration in response to infection in an endothelium dependent manner

Introduction

As the body's first line of defense against disease and infection, neutrophils must efficiently navigate to sites of inflammation; however, neutrophil dysregulation contributes to the pathogenesis of numerous diseases that leave people susceptible to infections. Many of these diseases are also associated with changes to the protein composition of the extracellular matrix. While it is known that neutrophils and endothelial cells, which play a key role in neutrophil activation, are sensitive to the mechanical and structural properties of the extracellular matrix, our understanding of how protein composition in the matrix affects the neutrophil response to infection is incomplete.

Methods

To investigate the effects of extracellular matrix composition on the neutrophil response to infection, we used an infection-on-a-chip microfluidic device that replicates a portion of a blood vessel endothelium surrounded by a model extracellular matrix. Model blood vessels were fabricated by seeding human umbilical vein endothelial cells on 2, 4, or 6 mg/mL type I collagen hydrogels. Primary human neutrophils were loaded into the endothelial lumens and stimulated by adding the bacterial pathogen Pseudomonas aeruginosa to the surrounding matrix.

Results

Collagen concentration did not affect the cell density or barrier function of the endothelial lumens. Upon infectious challenge, we found greater neutrophil extravasation into the 4 mg/mL collagen gels compared to the 6 mg/mL collagen gels. We further found that extravasated neutrophils had the highest migration speed and distance in 2mg/mL gels and that these values decreased with increasing collagen concentration. However, these phenomena were not observed in the absence of an endothelial lumen. Lastly, no differences in the percent of extravasated neutrophils producing reactive oxygen species were observed across the various collagen concentrations.

Discussion

Our study suggests that neutrophil extravasation and migration in response to an infectious challenge are regulated by collagen concentration in an endothelial cell-dependent manner. The results demonstrate how the mechanical and structural aspects of the tissue microenvironment affect the neutrophil response to infection. Additionally, these findings underscore the importance of developing and using microphysiological systems for studying the regulatory factors that govern the neutrophil response.

Identification of established and novel extracellular matrix components in glioblastoma as targets for angiogenesis and prognosis

Glioblastomas (GBM) are aggressive tumors known for their heterogeneity, rapid proliferation, treatment resistance, and extensive vasculature. Angiogenesis, the formation of new vessels, involves endothelial cell (EC) migration and proliferation. Various extracellular matrix (ECM) molecules regulate EC survival, migration, and proliferation. Culturing human brain EC (HBMEC) on GBM-derived ECM revealed a decrease in EC numbers compared to controls. Through in silico analysis, we explored ECM gene expression differences between GBM and brain normal glia cells and the impact of GBM microenvironment on EC ECM transcripts. ECM molecules such as collagen alpha chains (COL4A1, COL4A2, p < 0.0001); laminin alpha (LAMA4), beta (LAMB2), and gamma (LAMC1) chains (p < 0.0005); neurocan (NCAN), brevican (BCAN) and versican (VCAN) (p < 0.0005); hyaluronan synthase (HAS) 2 and metalloprotease (MMP) 2 (p < 0.005); MMP inhibitors (TIMP1-4, p < 0.0005), transforming growth factor beta-1 (TGFB1) and integrin alpha (ITGA3/5) (p < 0.05) and beta (ITGB1, p < 0.0005) chains showed increased expression in GBM. Additionally, GBM-influenced EC exhibited elevated expression of COL5A3, COL6A1, COL22A1 and COL27A1 (p < 0.01); LAMA1, LAMB1 (p < 0.001); fibulins (FBLN1/2, p < 0.01); MMP9, HAS1, ITGA3, TGFB1, and wingless-related integration site 9B (WNT9B) (p < 0.01) compared to normal EC. Some of these molecules: COL5A1/3, COL6A1, COL22/27A1, FBLN1/2, ITGA3/5, ITGB1 and LAMA1/B1 (p < 0.01); NCAN, HAS1, MMP2/9, TIMP1/2 and TGFB1 (p < 0.05) correlated with GBM patient survival. In conclusion, this study identified both established and novel ECM molecules regulating GBM angiogenesis, suggesting NCAN and COL27A1 are new potential prognostic biomarkers for GBM.

Biophysical and biochemical aspects of immune cell-tumor microenvironment interactions

The tumor microenvironment (TME), composed of and influenced by a heterogeneous set of cancer cells and an extracellular matrix, plays a crucial role in cancer progression. The biophysical aspects of the TME (namely, its architecture and mechanics) regulate interactions and spatial distributions of cancer cells and immune cells. In this review, we discuss the factors of the TME-notably, the extracellular matrix, as well as tumor and stromal cells-that contribute to a pro-tumor, immunosuppressive response. We then discuss the ways in which cells of the innate and adaptive immune systems respond to tumors from both biochemical and biophysical perspectives, with increased focus on CD8+ and CD4+ T cells. Building upon this information, we turn to immune-based antitumor interventions-specifically, recent biophysical breakthroughs aimed at improving CAR-T cell therapy.

Proteomic analysis of decellularized mice liver and kidney extracellular matrices

BACKGROUND

The extracellular matrix (ECM) is a three-dimensional network of proteins that encases and supports cells within a tissue and promotes physiological and pathological cellular differentiation and functionality. Understanding the complex composition of the ECM is essential to decrypt physiological processes as well as pathogenesis. In this context, the method of decellularization is a useful technique to eliminate cellular components from tissues while preserving the majority of the structural and functional integrity of the ECM.

RESULTS

In this study, we employed a bottom-up proteomic approach to elucidate the intricate network of proteins in the decellularized extracellular matrices of murine liver and kidney tissues. This approach involved the use of a novel, perfusion-based decellularization protocol to generate acellular whole organ scaffolds. Proteomic analysis of decellularized mice liver and kidney ECM scaffolds revealed tissue-specific differences in matrisome composition, while we found a predominantly stable composition of the core matrisome, consisting of collagens, glycoproteins, and proteoglycans. Liver matrisome analysis revealed unique proteins such as collagen type VI alpha-6, fibrillin-2 or biglycan. In the kidney, specific ECM-regulators such as cathepsin z were detected.

CONCLUSION

The identification of distinct proteomic signatures provides insights into how different matrisome compositions might influence the biological properties of distinct tissues. This experimental workflow will help to further elucidate the proteomic landscape of decellularized extracellular matrix scaffolds of mice in order to decipher complex cell-matrix interactions and their contribution to a tissue-specific microenvironment.

Host-microbe interactions at the blood-brain barrier through the lens of induced pluripotent stem cell-derived brain-like endothelial cells

Microbe-induced meningoencephalitis/meningitis is a life-threatening infection of the central nervous system (CNS) that occurs when pathogens are able to cross the blood-brain barrier (BBB) and gain access to the CNS. The BBB consists of highly specialized brain endothelial cells that exhibit specific properties to allow tight regulation of CNS homeostasis and prevent pathogen crossing. However, during meningoencephalitis/meningitis, the BBB fails to protect the CNS. Modeling the BBB remains a challenge due to the specialized characteristics of these cells. In this review, we cover the induced pluripotent stem cell-derived, brain-like endothelial cell model during host-pathogen interaction, highlighting the strengths and recent work on various pathogens known to interact with the BBB. As stem cell technologies are becoming more prominent, the stem cell-derived, brain-like endothelial cell model has been able to reveal new insights in vitro, which remain challenging with other in vitro cell-based models consisting of primary human brain endothelial cells and immortalized human brain endothelial cell lines.

Differential distribution of intermediate filament proteins in the bovine and ovine tongues

Intermediate filaments constitute the most heterogeneous class among the major classes of cytoskeletal proteins of mammalian cells. The 40 or more intermediate filament proteins have been classified into five types which show very specific rules of expression in specialized cell types. This study aimed to investigate the immunohistochemical distribution of cytokeratins (CKs) 8, 18, and 19 as well as the intermediate filaments vimentin, laminin, and desmin in bovine and ovine tongues. Immunohistochemical staining was performed for CKs 8, 18, 19, vimentin, laminin, and desmin. Our results revealed similar immunostaining intensity and distribution among various CKs, contrasting with distinct patterns for vimentin, laminin, and desmin. Immunoreactions were primarily localized in serous acini and ductal epithelium for cytokeratins, while vimentin and laminin were evident in connective tissue, endothelium, serous acini, and desmin in striated and smooth muscles. This study highlighted the absence of CKs 8, 18, 19, vimentin, and desmin in the lingual epithelium of bovine and ovine tongues. These findings enabled the classification of epithelial cells based on their specific cytokeratin patterns. Furthermore, vimentin was identified in mesodermal tissues and organs, desmin in muscle tissue, and laminin played crucial roles in basement membrane formation, nerve tissue regeneration, innervation of epithelial taste buds, and tissue separation and connection. Our findings provide essential insights into intermediate filament dynamics at the cellular and tissue levels. They serve as a foundation for future studies using systematic molecular biological techniques in this field.

Beta-Amyloid Enhances Vessel Formation in Organotypic Brain Slices Connected to Microcontact Prints

In Alzheimer's disease, the blood-brain barrier breakdown, blood vessel damage and re-organization are early events. Deposits of the small toxic peptide beta-amyloid (Aβ) cause the formation of extracellular plaques and accumulate in vessels disrupting the blood flow but may also play a role in blood clotting. In the present study, we aim to explore the impact of Aβ on the migration of endothelial cells and subsequent vessel formation. We use organotypic brain slices of postnatal day 10 wildtype mice (C57BL/6) and connect them to small microcontact prints (µCPs) of collagen. Our data show that laminin-positive endothelial cells migrate onto collagen µCPs, but without any vessel formation after 4 weeks. When the µCPs are loaded with human Aβ40, (aggregated) human Aβ42 and mouse Aβ42 peptides, the number and migration distance of endothelial cells are significantly reduced, but with a more pronounced subsequent vessel formation. The vessel formation is verified by zonula occludens (ZO)-1 and -2 stainings and confocal microscopy. In addition, the vessel formation is accompanied by a stronger GFAP-positive astroglial formation. Finally, we show that vessels can grow towards convergence when two opposed slices are connected via microcontact-printed lanes. In conclusion, our data show that Aβ promotes vessel formation, and organotypic brain slices connected to collagen µCPs provide a potent tool to study vessel formation.

Cellular and molecular mechanisms of fibrosis and resolution in bleomycin-induced pulmonary fibrosis mouse model revealed by spatial transcriptome analysis

The bleomycin-induced pulmonary fibrosis mouse model is commonly used in idiopathic pulmonary fibrosis research, but its cellular and molecular changes and efficiency as a model at the molecular level are not fully understood. In this study, we used spatial transcriptome technology to investigate the cellular and molecular changes in the lungs of bleomycin-induced pulmonary fibrosis mouse models. Our analyses revealed cell dynamics during fibrosis in epithelial cells, mesenchymal cells, immunocytes, and erythrocytes with their spatial distribution available. We confirmed the differentiation of the alveolar type II (AT2) cell type expressing Krt8, and we inferred their trajectories from both the AT2 cells and club cells. In addition to the fibrosis process, we also noticed evidence of self-resolving, especially to identify possible self-resolving related genes, including Prkca. Our findings provide insights into the cellular and molecular mechanisms underlying fibrosis resolution and represent the first spatiotemporal transcriptome dataset of the bleomycin-induced fibrosis mouse model.

The elusive brain perivascular fibroblast: a potential role in vascular stability and homeostasis

In the brain, perivascular fibroblasts (PVFs) reside within the perivascular spaces (PVSs) of arterioles and large venules, however their physiological and pathophysiological roles remain largely unknown. PVFs express numerous extracellular matrix proteins that are found in the basement membrane and PVS surrounding large diameter vessels. PVFs are sandwiched between the mural cell layer and astrocytic endfeet, where they are poised to interact with mural cells, perivascular macrophages, and astrocytes. We draw connections between the more well-studied PVF pro-fibrotic response in ischemic injury and the less understood thickening of the vascular wall and enlargement of the PVS described in dementia and neurodegenerative diseases. We postulate that PVFs may be responsible for stability and homeostasis of the brain vasculature, and may also contribute to changes within the PVS during disease.

The Activation of the LIMK/Cofilin Signaling Pathway via Extracellular Matrix-Integrin Interactions Is Critical for the Generation of Mature and Vascularized Cardiac Organoids

The generation of mature and vascularized human pluripotent stem cell-derived cardiac organoids (hPSC-COs) is necessary to ensure the validity of drug screening and disease modeling. This study investigates the effects of cellular aggregate (CA) stemness and self-organization on the generation of mature and vascularized hPSC-COs and elucidates the mechanisms underlying cardiac organoid (CO) maturation and vascularization. COs derived from 2-day-old CAs with high stemness (H-COs) and COs derived from 5-day-old CAs with low stemness (L-COs) were generated in a self-organized microenvironment via Wnt signaling induction. This study finds that H-COs exhibit ventricular, structural, metabolic, and functional cardiomyocyte maturation and vessel networks consisting of endothelial cells, smooth muscle cells, pericytes, and basement membranes compared to L-COs. Transcriptional profiling shows the upregulation of genes associated with cardiac maturation and vessel formation in H-COs compared with the genes in L-COs. Through experiments with LIMK inhibitors, the activation of ROCK-LIMK-pCofilin via ECM-integrin interactions leads to cardiomyocyte maturation and vessel formation in H-COs. Furthermore, the LIMK/Cofilin signaling pathway induces TGFβ/NODAL and PDGF pathway activation for the maturation and vascularization of H-COs. The study demonstrates for the first time that LIMK/Cofilin axis activation plays an important role in the generation of mature and vascularized COs.

Development and repair of blood vessels in the zebrafish spinal cord

The vascular system is inefficiently repaired after spinal cord injury (SCI) in mammals, resulting in secondary tissue damage and immune deregulation that contribute to the limited functional recovery. Unlike mammals, zebrafish can repair the spinal cord (SC) and restore motility, but the vascular response to injury has not been investigated. Here, we describe the zebrafish SC blood vasculature, starting in development with the initial vessel ingression in a body size-dependent manner, the acquisition of perivascular support and the establishment of ventral to dorsal blood circulation. The vascular organization grows in complexity and displays multiple barrier specializations in adulthood. After injury, vessels rapidly regrow into the lesion, preceding the glial bridge and axons. Vascular repair involves an early burst of angiogenesis that creates dysmorphic and leaky vessels. Dysfunctional vessels are later removed, as pericytes are recruited and the blood-SC barrier is re-established. This study demonstrates that zebrafish can successfully re-vascularize the spinal tissue, reinforcing the value of this organism as a regenerative model for SCI.

The Stereotypic Response of the Pulmonary Vasculature to Respiratory Viral Infections: Findings in Mouse Models of SARS-CoV-2, Influenza A and Gammaherpesvirus Infections

The respiratory system is the main target of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the cause of coronavirus disease 19 (COVID-19) where acute respiratory distress syndrome is considered the leading cause of death. Changes in pulmonary blood vessels, among which an endothelialitis/endotheliitis has been particularly emphasized, have been suggested to play a central role in the development of acute lung injury. Similar vascular changes are also observed in animal models of COVID-19. The present study aimed to determine whether the latter are specific for SARS-CoV-2 infection, investigating the vascular response in the lungs of mice infected with SARS-CoV-2 and other respiratory viruses (influenza A and murine gammaherpesvirus) by in situ approaches (histology, immunohistology, morphometry) combined with RNA sequencing and bioinformatic analysis. Non-selective recruitment of monocytes and T and B cells from larger muscular veins and arteries was observed with all viruses, matched by a comparable transcriptional response. There was no evidence of endothelial cell infection in any of the models. Both the morphological investigation and the transcriptomics approach support the interpretation that the lung vasculature in mice mounts a stereotypic response to alveolar and respiratory epithelial damage. This may have implications for the treatment and management of respiratory disease in humans.

Bicuspid aortic valve aortopathy is characterized by embryonic epithelial to mesenchymal transition and endothelial instability

Bicuspid aortic valve (BAV) is the most common congenital heart malformation frequently associated with ascending aortic aneurysm (AscAA). Epithelial to mesenchymal transition (EMT) may play a role in BAV-associated AscAA. The aim of the study was to investigate the type of EMT associated with BAV aortopathy using patients with a tricuspid aortic valve (TAV) as a reference. The state of the endothelium was further evaluated. Aortic biopsies were taken from patients undergoing open-heart surgery. Aortic intima/media miRNA and gene expression was analyzed using Affymetrix human transcriptomic array. Histological staining assessed structure, localization, and protein expression. Migration/proliferation was assessed using ORIS migration assay. We show different EMT types associated with BAV and TAV AscAA. Specifically, in BAV-associated aortopathy, EMT genes related to endocardial cushion formation were enriched. Further, BAV vascular smooth muscle cells were less proliferative and migratory. In contrast, TAV aneurysmal aortas displayed a fibrotic EMT phenotype with medial degenerative insults. Further, non-dilated BAV aortas showed a lower miRNA-200c-associated endothelial basement membrane LAMC1 expression and lower CD31 expression, accompanied by increased endothelial permeability indicated by increased albumin infiltration. Embryonic EMT is a characteristic of BAV aortopathy, associated with endothelial instability and vascular permeability of the non-dilated aortic wall. KEY MESSAGES: Embryonic EMT is a feature of BAV-associated aortopathy. Endothelial integrity is compromised in BAV aortas prior to dilatation. Non-dilated BAV ascending aortas are more permeable than aortas of tricuspid aortic valve patients.

Mouse embryonic stem cell-derived blood-brain barrier model: applicability to studying antibody triggered receptor mediated transcytosis

Blood brain barrier (BBB) models in vitro are an important tool to aid in the pre-clinical evaluation and selection of BBB-crossing therapeutics. Stem cell derived BBB models have recently demonstrated a substantial advantage over primary and immortalized brain endothelial cells (BECs) for BBB modeling. Coupled with recent discoveries highlighting significant species differences in the expression and function of key BBB transporters, the field is in need of robust, species-specific BBB models for improved translational predictability. We have developed a mouse BBB model, composed of mouse embryonic stem cell (mESC-D3)-derived brain endothelial-like cells (mBECs), employing a directed monolayer differentiation strategy. Although the mBECs showed a mixed endothelial-epithelial phenotype, they exhibited high transendothelial electrical resistance, inducible by retinoic acid treatment up to 400 Ω cm². This tight cell barrier resulted in restricted sodium fluorescein permeability (1.7 × 10^-5 cm/min), significantly lower than that of bEnd.3 cells (1.02 × 10^-3 cm/min) and comparable to human induced pluripotent stem cell (iPSC)-derived BECs (2.0 × 10^-5 cm/min). The mBECs expressed tight junction proteins, polarized and functional P-gp efflux transporter and receptor mediated transcytosis (RMT) receptors; collectively important criteria for studying barrier regulation and drug delivery applications in the CNS. In this study, we compared transport of a panel of antibodies binding species selective or cross-reactive epitopes on BBB RMT receptors in both the mBEC and human iPSC-derived BEC model, to demonstrate discrimination of species-specific BBB transport mechanisms.

Integrin expression and extracellular matrix adhesion of septoclasts, pericytes, and endothelial cells at the chondro-osseous junction and the metaphysis of the proximal tibia in young mice

We previously reported that septoclasts, which are uncalcified growth plate (GP) cartilage matrix-resorbing cells, are derived from pericytes surrounding capillary endothelial cells. Resorption of the GP is assumed to be regulated synchronously by septoclasts, pericytes, and endothelial cells. To reveal the contribution of the extracellular matrix (ECM) to the regulatory mechanisms of septoclastic cartilage resorption, we investigated the spatial correlation between the cells and the ECM in the GP matrix and basement membrane (BM) and investigated the expression of integrins-ECM receptors-in the cells. Septoclasts attached to the transverse septa containing collagen-II/-X at the tip of their processes and to the longitudinal septa containing collagen-II/-X at the spine-like processes extending from their bodies and processes. Collagen-IV and laminin α4 in the BM were sparsely detected between septoclasts and capillary endothelial cells at the chondro-osseous junction (COJ) and were absent in the outer surface of pericytes at the metaphysis. Integrin α1/α2, integrin α1, and integrin α2/α6 were detected in the cell membranes of septoclasts, pericytes, and endothelial cells, respectively. These results suggest that the adhesion between septoclasts and the cartilage ECM forming the scaffolds for cartilage resorption and migration is provided by integrin α2-collagen-II/-X interaction and that the adhesions between the BM and pericytes or endothelial cells are mediated by integrin α1-collagen-IV and integrin α2/α6-laminin interaction, respectively.

Interleukin-6 trans-signaling induced laminin switch contributes to reduced trans-endothelial migration of granulocytic cells

BACKGROUND AND AIMS

Laminins are essential components of the endothelial basement membrane, which predominantly contains LN421 and LN521 isoforms. Regulation of laminin expression under pathophysiological conditions is largely unknown. In this study, we aimed to investigate the role of IL-6 in regulating endothelial laminin profile and characterize the impact of altered laminin composition on the phenotype, inflammatory response, and function of endothelial cells (ECs).

METHODS

HUVECs and HAECs were used for in vitro experiments. Trans-well migration experiments were performed using leukocytes isolated from peripheral blood of healthy donors. The BiKE cohort was used to assess expression of laminins in atherosclerotic plaques and healthy vessels. Gene and protein expression was analyzed using Microarray/qPCR and proximity extension assay, ELISA, immunostaining or immunoblotting techniques, respectively.

RESULTS

Stimulation of ECs with IL-6+sIL-6R, but not IL-6 alone, reduces expression of laminin α4 (LAMA4) and increases laminin α5 (LAMA5) expression at the mRNA and protein levels. In addition, IL-6+sIL-6R stimulation of ECs differentially regulates the release of several proteins including CXCL8 and CXCL10, which collectively were predicted to inhibit granulocyte transmigration. Experimentally, we demonstrated that granulocyte migration is inhibited across ECs pre-treated with IL-6+sIL-6R. In addition, granulocyte migration across ECs cultured on LN521 was significantly lower compared to LN421. In human atherosclerotic plaques, expression of endothelial LAMA4 and LAMA5 is significantly lower compared to control vessels. Moreover, LAMA5-to-LAMA4 expression ratio was negatively correlated with granulocytic cell markers (CD177 and myeloperoxidase (MPO)) and positively correlated with T-lymphocyte marker CD3.

CONCLUSIONS

We showed that expression of endothelial laminin alpha chains is regulated by IL-6 trans-signaling and contributes to inhibition of trans-endothelial migration of granulocytic cells. Further, expression of laminin alpha chains is altered in human atherosclerotic plaques and is related to intra-plaque abundance of leukocyte subpopulations.

A Lamb1Dendra2 mouse model identifies basement-membrane-producing origins and dynamics in PyMT breast tumors

The basement membrane (BM) around tumor lobes forms a barrier to prevent cancer cells from invading the surrounding tissue. Although myoepithelial cells are key producers of the healthy mammary epithelium BM, they are nearly absent in mammary tumors. To study the origin and dynamics of the BM, we developed and imaged a laminin beta1-Dendra2 mouse model. We show that the turnover of laminin beta1 is faster in the BMs that surround the tumor lobes than in the BMs that surround the healthy epithelium. Moreover, we find that epithelial cancer cells and tumor-infiltrating endothelial cells synthesize laminin beta1 and that this production is temporarily and locally heterogeneous, leading to local discontinuity of the BM laminin beta1. Collectively, our data draw a new paradigm for tumor BM turnover in which the disassembly happens at a constant rate, and a local misbalance of compensating production leads to reduction or even complete disappearance of the BM.

Extracellular matrix proteins in construction and function of in vitro blood-brain barrier models

The blood-brain barrier (BBB) is a highly impermeable barrier separating circulating blood and brain tissue. A functional BBB is critical for brain health, and BBB dysfunction has been linked to the pathophysiology of diseases such as stroke and Alzheimer’s disease. A variety of models have been developed to study the formation and maintenance of the BBB, ranging from in vivo animal models to in vitro models consisting of primary cells or cells differentiated from human pluripotent stem cells (hPSCs). These models must consider the composition and source of the cellular components of the neurovascular unit (NVU), including brain microvascular endothelial cells (BMECs), brain pericytes, astrocytes, and neurons, and how these cell types interact. In addition, the non-cellular components of the BBB microenvironment, such as the brain vascular basement membrane (BM) that is in direct contact with the NVU, also play key roles in BBB function. Here, we review how extracellular matrix (ECM) proteins in the brain vascular BM affect the BBB, with a particular focus on studies using hPSC-derived in vitro BBB models, and discuss how future studies are needed to advance our understanding of how the ECM affects BBB models to improve model performance and expand our knowledge on the formation and maintenance of the BBB.

Association of LAMA1 Single-Nucleotide Polymorphisms with Risk of Esophageal Squamous Cell Carcinoma among the Eastern Chinese Population

Introduction

LAMA1, also known as laminin subunit α1, is a member of the laminin family, which is widely reported to be a key basement membrane molecule that affects various biological activities and is associated with many kinds of diseases. We aimed to investigate the association between LAMA1single-nucleotide polymorphisms and the occurrence and progression of esophageal squamous cell carcinoma in the Chinese population.

Method

2,186 participants were collected retrospectively between October 2008 and January 2017, including 1,043 ESCC patients and 1,143 noncancer patients. A 2 mL blood sample was obtained intravenously for the LDR for SNP analysis. The 6 SNP loci of LAMA1 were selected and examined. We analyzed the association of several genetic models of 6 LAMA1 SNP loci, sex, age, smoking and drinking status, and the occurrence of esophageal squamous cell carcinoma.

Results

In the rs62081531 G > A locus, genotype GA was a protective factor for ESCC compared with GG (OR: 0.830, P=0.046), especially among the younger and nondrinkers. At rs607230 T > C, genotype TC was linked with a lower risk of ESCC compared with TT. (OR: 0.613, P=0.034). Haplotype Frequencies revealed that A_rs62081531G_rs621993A_rs539713T_rs566655A_rs73938538C_rs607230 (OR: 0.803, P=0.028) and G_rs62081531G_rs621993A_rs539713T_rs566655C_rs73938538C_rs607230 (OR: 0.679, P=0.010) were strongly associated with lower susceptibility of ESCC.

Conclusion

The LAMA1 rs62081531, rs539713, rs566655, and rs607230 polymorphisms were demonstrated to be related to susceptibility to ESCC in the Chinese population. LAMA1 SNPs may have a significant impact on the occurrence of esophageal cancer and may serve as potential diagnostic biomarkers.

Mimicking the neural stem cell niche: An engineer’s view of cell: material interactions

Neural stem cells have attracted attention in recent years to treat neurodegeneration. There are two neurogenic regions in the brain where neural stem cells reside, one of which is called the subventricular zone (SVZ). The SVZ niche is a complicated microenvironment providing cues to regulate self-renewal and differentiation while maintaining the neural stem cell’s pool. Many scientists have spent years understanding the cellular and structural characteristics of the SVZ niche, both in homeostasis and pathological conditions. On the other hand, engineers focus primarily on designing platforms using the knowledge they acquire to understand the effect of individual factors on neural stem cell fate decisions. This review provides a general overview of what we know about the components of the SVZ niche, including the residing cells, extracellular matrix (ECM), growth factors, their interactions, and SVZ niche changes during aging and neurodegenerative diseases. Furthermore, an overview will be given on the biomaterials used to mimic neurogenic niche microenvironments and the design considerations applied to add bioactivity while meeting the structural requirements. Finally, it will discuss the potential gaps in mimicking the microenvironment.

A novel approach for the endothelialization of xenogeneic decellularized vascular tissues by human cells utilizing surface modification and dynamic culture

Decellularized xenogeneic vascular grafts can be used in revascularization surgeries. We have developed decellularization methods using high hydrostatic pressure (HHP), which preserves the extracellular structure. Here, we attempted ex vivo endothelialization of HHP-decellularized xenogeneic tissues using human endothelial cells (ECs) to prevent clot formation against human blood. Slices of porcine aortic endothelium were decellularized using HHP and coated with gelatin. Human umbilical vein ECs were directly seeded and cultured under dynamic flow or static conditions for 14 days. Dynamic flow cultures tend to demonstrate higher cell coverage. We then coated the tissues with the E8 fragment of human laminin-411 (hL411), which has high affinity for ECs, and found that Dynamic/hL411showed high area coverage, almost reaching 100% (Dynamic/Gelatin vs Dynamic/hL411; 58.7 ± 11.4 vs 97.5 ± 1.9%, P = 0.0017). Immunostaining revealed sufficient endothelial cell coverage as a single cell layer in Dynamic/hL411. A clot formation assay using human whole blood showed low clot formation in Dynamic/hL411, almost similar to that in the negative control, polytetrafluoroethylene. Surface modification of HHP-decellularized xenogeneic endothelial tissues combined with dynamic culture achieved sufficient ex vivo endothelialization along with prevention of clot formation, indicating their potential for clinical use as vascular grafts in the future.

Laminin N-terminus (LaNt) proteins, laminins and basement membrane regulation

Basement membranes (BMs) are structured regions of the extracellular matrix that provide multiple functions including physical support and acting as a barrier, as a repository for nutrients and growth factors, and as biophysical signalling hubs. At the core of all BMs is the laminin (LM) family of proteins. These large heterotrimeric glycoproteins are essential for tissue integrity, and differences between LM family members represent a key nexus in dictating context and tissue-specific functions. These variations reflect genetic diversity within the family, which allows for multiple structurally and functionally distinct heterotrimers to be produced, each with different architectures and affinities for other matrix proteins and cell surface receptors. The ratios of these LM isoforms also influence the biophysical properties of a BM owing to differences in their relative ability to form polymers or networks. Intriguingly, the LM superfamily is further diversified through the related netrin family of proteins and through alternative splicing leading to the generation of non-LM short proteins known as the laminin N-terminus (LaNt) domain proteins. Both the netrins and LaNt proteins contain structural domains involved in LM-to-LM interaction and network assembly. Emerging findings indicate that one netrin and at least one LaNt protein can potently influence the structure and function of BMs, disrupting the networks, changing physical properties, and thereby influencing tissue function. These findings are altering the way that we think about LM polymerisation and, in the case of the LaNt proteins, suggest a hitherto unappreciated form of LM self-regulation.

Generation of Brain Microvascular Endothelial-like Cells from Human iPS Cell-Derived Endothelial Progenitor Cells Using TGF-β Receptor Inhibitor, Laminin 511 Fragment, and Neuronal Cell Culture Supplements

Brain microvascular endothelial cells (BMECs) constitute the blood-brain barrier (BBB), which prevents the transfer of substances into the brain. Recently, in vitro BBB models using human-induced pluripotent stem (iPS) cell-derived brain microvascular endothelial-like cells (iBMELCs) have been created. However, it is suggested that iBMELCs differentiated by the existing methods are different from the BMECs that occur in vivo. This study aimed to establish iBMELCs generated via human iPS cell-derived endothelial progenitor cells (iEPCs) (E-iBMELCs). Expanded and cryopreserved iEPCs were thawed and differentiated into mature endothelial cells under various conditions. Intercellular barriers were significantly enhanced in E-iBMELCs using a B-27 supplement, transforming growth factor-β receptor inhibitor, and laminin 511 fragment. Expression of the endothelial cell markers was higher in the E-iBMELCs generated in this study compared with conventional methods. In addition, E-iBMELCs expressed P-glycoprotein. E-iBMELCs developed in this study will significantly contribute to drug discovery for neurodegenerative diseases and might elucidate the pathogenesis of neurodegenerative diseases associated with BBB disruption.

Cell-specific expression and function of laminin at the neurovascular unit

Laminin, a major component of the basal lamina (BL), is a heterotrimeric protein with many isoforms. In the CNS, laminin is expressed by almost all cell types, yet different cells synthesize distinct laminin isoforms. By binding to its receptors, laminin exerts a wide variety of important functions. However, due to the reciprocal and cell-specific expression of laminin in different cells at the neurovascular unit, its functions in blood-brain barrier (BBB) maintenance and BBB repair after injury are not fully understood. In this review, we focus on the expression and functions of laminin and its receptors in the neurovascular unit under both physiological and pathological conditions. We first briefly introduce the structures of laminin and its receptors. Next, the expression and functions of laminin and its receptors in the CNS are summarized in a cell-specific manner. Finally, we identify the knowledge gap in the field and discuss key questions that need to be answered in the future. Our goal is to provide a comprehensive overview on cell-specific expression of laminin and its receptors in the CNS and their functions on BBB integrity.

New Insight on 2D In Vitro Angiogenesis Models: All That Stretches Is Not a Tube

Highlights

Abstract

A Matrigel-based tube formation assay is a simple and widely accepted 2D angiogenesis model in vitro. Extracellular matrix (EM) proteins and growth factors (GFs) from Matrigel^TM exclusively trigger endothelial cell (EC) tubular network (ETN) formation. Co-culture of ECs with mesenchymal stromal cells (MSCs) is another and more reliable in vitro angiogenesis assay. MSCs modulate ETN formation through intercellular interactions and as a supplier of EM and GFs. The aim of the present study was to compare the expression profile of ECs in both models. We revealed upregulation of the uPA, uPAR, Jagged1, and Notch2 genes in dividing/migrating ECs and for ECs in both experimental models at 19 h. The expression of endothelial–mesenchymal transition genes largely increased in co-cultured ECs whereas Notch and Hippo signaling pathway genes were upregulated in ECs on Matrigel^TM. We showed that in the co-culture model, basement membrane (BM) deposition is limited only to cell-to-cell contacts in contrast to Matrigel^TM, which represents by itself fully pre-assembled BM matrix. We suggest that ETN in a co-culture model is still in a dynamic process due to immature BM whereas ECs in the Matrigel^TM assay seem to be at the final stage of ETN formation.

Genetic Disorders of the Extracellular Matrix: From Cell and Gene Therapy to Future Applications in Regenerative Medicine

Metazoans have evolved to produce various types of extracellular matrix (ECM) that provide structural support, cell adhesion, cell-cell communication, and regulated exposure to external cues. Epithelial cells produce and adhere to a specialized sheet-like ECM, the basement membrane, that is critical for cellular homeostasis and tissue integrity. Mesenchymal cells, such as chondrocytes in cartilaginous tissues and keratocytes in the corneal stroma, produce a pericellular matrix that presents optimal levels of growth factors, cytokines, chemokines, and nutrients to the cell and regulates mechanosensory signals through specific cytoskeletal and cell surface receptor interactions. Here, we discuss laminins, collagen types IV and VII, and perlecan, which are major components of these two types of ECM. We examinegenetic defects in these components that cause basement membrane pathologies such as epidermolysis bullosa, Alport syndrome, rare pericellular matrix-related chondrodysplasias, and corneal keratoconus and discuss recent advances in cell and gene therapies being developed for some of these disorders.

Glyoxal Fixation Is Optimal for Immunostaining of Brain Vessels, Pericytes and Blood-Brain Barrier Proteins

Brain vascular staining is very important for understanding cerebrovascular pathologies. 4% paraformaldehyde is considered the gold standard fixation technique for immunohistochemistry and it revolutionized the examination of proteins in fixed tissues. However, this fixation technique produces inconsistent immunohistochemical staining results due to antigen masking. Here, we test a new fixation protocol using 3% glyoxal and demonstrate that this method improves the staining of the brain vasculature, pericytes, and tight junction proteins compared to 4% paraformaldehyde. Use of this new fixation technique will provide more detailed information about vascular protein expressions, their distributions, and colocalizations with other proteins at the molecular level in the brain vasculature.

Organ-specific endothelial cell heterogenicity and its impact on regenerative medicine and biomedical engineering applications

Endothelial cells (ECs) are a key cellular component of the vascular system as they form the inner lining of the blood vessels. Recent findings highlight that ECs express extensive phenotypic heterogenicity when following the vascular tree from the major vasculature down to the organ capillaries. However, in vitro models, used for drug development and testing, or to study the role of ECs in health and disease, rarely acknowledge this EC heterogenicity. In this review, we highlight the main differences between different EC types, briefly summarize their different characteristics and focus on the use of ECs in in vitro models. We introduce different approaches on how ECs can be utilized in co-culture test systems in the field of brain, pancreas, and liver research to study the role of the endothelium in health and disease. Finally, we discuss potential improvements to current state-of-the-art in vitro models and future directions.

New Insights Into the Persistent Effects of Acute Exposure to AFB1 on Rat Liver

Aflatoxin B₁ (AFB₁) has mutagenesis, carcinogenesis and teratogenesis effects and mainly found in food crops and their processed foods. AFB₁ exposure can cause acute or chronic liver poisoning, but there were few studies on the persistent effects of acute AFB₁ exposure on the liver. In this study, rat liver injury models were established 2 and 7 days after single exposure to high and low doses of AFB₁. The persistent effects of AFB₁ single acute exposure (ASAE) on rat liver were analyzed from the phenotypic and genetic levels. The results showed that compared with the control group, liver function indexes, MDA content in liver and the number of apoptotic hepatocytes in model groups increased to the highest on the 2nd day after ASAE (p < 0.001). However, the changes of liver coefficient were most significant on the 7th day after ASAE (p < 0.01). The results of liver pathology showed that the liver injury was not alleviated and the activities of antioxidant enzymes GSH-Px and SOD were the lowest on the 7th day (p < 0.001). RNA-Seq results indicated that there were 236, 33, 679, and 78 significantly differentially expressed genes (DEGs) in the model groups (LA-2d, LA-7d, HA-2d, HA-7d) compared with the control group. Among them, the Gtse1 gene related to the proliferation, differentiation and metastasis of liver cancer cells, the Lama5 and Fabp4 gene related to the inflammatory response were significantly DEGs in the four model groups, and the differential expression of the immune system-related Bcl6 gene increased with the prolonged observation time after ASAE. In conclusion, ASAE can cause persistent liver damage in rats. The persistently affected genes Lama5, Gtse1, Fabp4, and Bcl6 possess the potential to be therapeutic targets for liver disease induced by AFB₁.

Laminin N-terminus α31 expression during development is lethal and causes widespread tissue-specific defects in a transgenic mouse model

Laminins (LMs) are essential components of all basement membranes where they regulate an extensive array of tissue functions. Alternative splicing from the laminin α3 gene produces a non‐laminin but netrin‐like protein, Laminin N terminus α31 (LaNt α31). LaNt α31 is widely expressed in intact tissue and is upregulated in epithelial cancers and during wound healing. In vitro functional studies have shown that LaNt α31 can influence numerous aspects of epithelial cell behavior via modifying matrix organization, suggesting a new model of laminin auto‐regulation. However, the function of this protein has not been established in vivo. Here, a mouse transgenic line was generated using the ubiquitin C promoter to drive inducible expression of LaNt α31. When expression was induced at embryonic day 15.5, LaNt α31 transgenic animals were not viable at birth, exhibiting localized regions of erythema. Histologically, the most striking defect was widespread evidence of extravascular bleeding across multiple tissues. Additionally, LaNt α31 transgene expressing animals exhibited kidney epithelial detachment, tubular dilation, disruption of the epidermal basal cell layer and of the hair follicle outer root sheath, and ~50% reduction of cell numbers in the liver, associated with depletion of hematopoietic erythrocytic foci. These findings provide the first in vivo evidence that LaNt α31 can influence tissue morphogenesis.

Peroxynitrous acid-modified extracellular matrix alters gene and protein expression in human coronary artery smooth muscle cells and induces a pro-inflammatory phenotype

Leukocytes produce oxidants at inflammatory sites, including within the artery wall during the development of atherosclerosis. Developing lesions contain high numbers of activated leukocytes that generate reactive nitrogen species, including peroxynitrite/peroxynitrous acid (ONOO^-/ONOOH), as evidenced by the presence of oxidized/nitrated molecules including extracellular matrix (ECM) proteins. ECM materials are critical for arterial wall integrity, function, and determine cell phenotype, with smooth muscle cells undergoing a phenotypic switch from quiescent/contractile to proliferative/synthetic during disease development. We hypothesized that ECM modification by ONOO^-/ONOOH might drive this switch, and thereby potentially contribute to atherogenesis. ECM generated by primary human coronary artery smooth muscle cells (HCASMCs) was treated with increasing ONOO^-/ONOOH concentrations (1-1000 μM). This generated significant damage on laminin, fibronectin and versican, and lower levels on collagens and glycosaminoglycans, together with the increasing concentrations of the damage biomarker 3-nitrotyrosine. Adhesion of naïve HCASMC to ECM modified by 1 μM ONOO^-/ONOOH was enhanced, but significantly diminished by higher ONOO^-/ONOOH treatment. Cell proliferation and metabolic activity were significantly enhanced by 100 μM ONOO^-/ONOOH pre-treatment. These changes were accompanied by increased expression of genes involved in mitosis (PCNA, CCNA1, CCNB1), ECM (LAMA4, LAMB1, VCAN, FN1) and inflammation (IL-1B, IL-6, VCAM-1), and corresponding protein secretion (except VCAM-1) into the medium. These changes induced by modified ECM are consistent with HCASMC switching to a synthetic/proliferative/pro-inflammatory phenotype, together with ECM remodelling. These changes model those in atherosclerosis, suggesting a link between oxidant-modified ECM and disease progression, and highlight the potential of targeting oxidant generation as a therapeutic strategy.

Laminin matrix regulates beta-cell FGFR5 expression to enhance glucose-stimulated metabolism

We previously showed that pancreatic beta-cells plated on laminin matrix express reduced levels of FGFR1, a receptor linked to beta-cell metabolism and differentiation. Due to recent evidence that adult beta-cells also express FGFR5, a co-receptor for FGFR1, we now aim to determine the effect of laminin on FGFR5 expression and consequent effects on beta-cell metabolism. Using a genetically encoded sensor for NADPH/NADP⁺ redox state (Apollo-NADP⁺), we show overexpression of FGFR5 enhances glucose-stimulated NADPH metabolism in beta-cell lines as well as mouse and human beta-cells. This enhanced response was accompanied by increased insulin secretion as well as increased expression of transcripts for glycolytic enzymes (Glucokinase/GCK, PKM2) and the functional maturity marker Urocortin 3 (UCN3). Culturing beta-cells on laminin matrix also stimulated upregulation of endogenous FGFR5 expression, and similarly enhanced beta-cell glucose-stimulated NADPH-metabolism as well as GCK and PKM2 transcript expression. The metabolism and transcript responses triggered by laminin were disrupted by R5ΔC, a truncated receptor isoform that inhibits the FGFR5/FGFR1 signaling complex. Collectively these data reveal that beta-cells respond to laminin by increasing FGFR5 expression to enhance beta-cell glucose metabolism.

Fluid transport in the brain

The brain harbors a unique ability to, figuratively speaking, shift its gears. During wakefulness, the brain is geared fully toward processing information and behaving, while homeostatic functions predominate during sleep. The blood-brain barrier establishes a stable environment that is optimal for neuronal function, yet the barrier imposes a physiological problem; transcapillary filtration that forms extracellular fluid in other organs is reduced to a minimum in brain. Consequently, the brain depends on a special fluid [the cerebrospinal fluid (CSF)] that is flushed into brain along the unique perivascular spaces created by astrocytic vascular endfeet. We describe this pathway, coined the term glymphatic system, based on its dependency on astrocytic vascular endfeet and their adluminal expression of aquaporin-4 water channels facing toward CSF-filled perivascular spaces. Glymphatic clearance of potentially harmful metabolic or protein waste products, such as amyloid-β, is primarily active during sleep, when its physiological drivers, the cardiac cycle, respiration, and slow vasomotion, together efficiently propel CSF inflow along periarterial spaces. The brain's extracellular space contains an abundance of proteoglycans and hyaluronan, which provide a low-resistance hydraulic conduit that rapidly can expand and shrink during the sleep-wake cycle. We describe this unique fluid system of the brain, which meets the brain's requisites to maintain homeostasis similar to peripheral organs, considering the blood-brain-barrier and the paths for formation and egress of the CSF.