Type IV collagen-derived angiogenesis inhibitors

Metabolic dysfunction-associated liver disease and diabetes: Matrix remodeling, fibrosis, and therapeutic implications

Metabolic dysfunction-associated liver disease (MASLD) and steatohepatitis (MASH) are becoming the most common causes of chronic liver disease in the United States and worldwide due to the obesity and diabetes epidemics. It is estimated that by 2030 close to 100 million people might be affected and patients with type 2 diabetes are especially at high risk. Twenty to 30% of patients with MASLD can progress to MASH, which is characterized by steatosis, necroinflammation, hepatocyte ballooning, and in advanced cases, fibrosis progressing to cirrhosis. Clinically, it is recognized that disease progression in diabetic patients is accelerated and the role of various genetic and epigenetic factors, as well as cell-matrix interactions in fibrosis and stromal remodeling, have recently been recognized. While there has been great progress in drug development and clinical trials for MASLD/MASH, the complexity of these pathways highlights the need to improve diagnosis/early detection and develop more successful antifibrotic therapies that not only prevent but reverse fibrosis.

Isolated Fragments of Intact Microvessels: Tissue Vascularization, Modeling, and Therapeutics

The microvasculature is integral to nearly every tissue in the body, providing not only perfusion to and from the tissue, but also homing sites for immune cells, cellular niches for tissue dynamics, and cooperative interactions with other tissue elements. As a microtissue itself, the microvasculature is a composite of multiple cell types exquisitely organized into structures (individual vessel segments and extensive vessel networks) capable of considerable dynamics and plasticity. Consequently, it has been challenging to include a functional microvasculature in assembled or fabricated tissues. Isolated fragments of intact microvessels, which retain the cellular composition and structures of native microvessels, are proving effective in a variety of vascularization applications including tissue in vitro disease modeling, vascular biology, mechanistic discovery, and tissue prevascularization in regenerative therapeutics and grafting. In this review, we will discuss the importance of recapitulating native tissue biology and the successful vascularization applications of isolated microvessels.

CDK4/6 inhibitors induce breast cancer senescence with enhanced anti-tumor immunogenic properties compared with DNA-damaging agents

Since therapy-induced senescence (TIS) can either support or inhibit cancer progression, identifying which types of chemotherapeutic agents can produce the strongest anti-tumor TIS is an important issue. Here, cyclin-dependent kinase4/6 inhibitors (CDK4/6i)-induced senescence was compared to the TIS induced by conventional DNA-damaging agents. Despite both types of agents eliciting a similar degree of senescence, we observed increased expression of the senescence-associated secretory phenotype (SASP) and ligands related to pro-tumor immunity (IL6, CXCL8, TGFβ, CD274, and CEACAM1) and angiogenesis (VEGFA) mainly in TIS induced by DNA-damaging agents rather than by CDK4/6i. Additionally, although all agents increased the expression of anti-tumor immunomodulatory proteins related to antigen presentation (MHC-I, B2M) and T cell chemokines (CXCL9, 10, 11), CDK4/6i-induced senescent cells still maintained this expression at a similar or even higher intensity than cells treated with DNA-damaging agents, despite the absence of nuclear factor-kappa-B (NF-κB) and p53 activation. These data suggest that in contrast with DNA-damaging agents, which augment the pro-tumorigenic microenvironment via pro-inflammatory SASP, CDK4/6i can generate TIS only with antitumor immunomodulatory proteins.

Fucoidan/collagen composite coating on magnesium alloy for better corrosion resistance and pro-endothelialization potential

Magnesium alloy stents (MAS) have broad application prospects in the treatment of cardiovascular diseases. However, poor corrosion resistance and biocompatibility greatly limit the clinical application of MAS. In this work, the coating consisting of MgF2 layer, polydopamine layer, fucoidan and collagen IV was constructed on Mg-Zn-Y-Nd (ZE21B) alloy to improve its corrosion resistance and pro-endothelialization potential. The fucoidan and collagen IV in the coating could obviously enhance the hemocompatibility and pro-endothelialization potential respectively. Compared with bare ZE21B alloy, the fucoidan/collagen composite coating modified ZE21B alloy possessed lower corrosion current density and better corrosion resistance. Moreover, the modified ZE21B alloy exhibited relatively low hemolysis rate, fibrinogen adsorption and platelet adhesion in the blood experiments, suggesting the improved hemocompatibility. Furthermore, the modified ZE21B alloy favorably supported the adhesion and proliferation of vascular endothelial cells (ECs) and effectively regulated the phenotype of smooth muscle cells (SMCs), thus improving the pro-endothelialization potential of vascular stent materials. The fucoidan/collagen composite coating can significantly improve the corrosion resistance and pro-endothelialization potential of ZE21B alloy, showing great potential in the development of degradable MAS.

Prostate Cancer Microvascular Routes: Exploration and Measurement Strategies

Angiogenesis is acknowledged as a pivotal feature in the pathology of human cancer. Despite the absence of universally accepted markers for gauging the comprehensive angiogenic activity in prostate cancer (PCa) that could steer the formulation of focused anti-angiogenic treatments, the scrutiny of diverse facets of tumoral blood vessel development may furnish significant understanding of angiogenic processes. Malignant neoplasms, encompassing PCa, deploy a myriad of strategies to secure an adequate blood supply. These modalities range from sprouting angiogenesis and vasculogenesis to intussusceptive angiogenesis, vascular co-option, the formation of mosaic vessels, vasculogenic mimicry, the conversion of cancer stem-like cells into tumor endothelial cells, and vascular pruning. Here we provide a thorough review of these angiogenic mechanisms as they relate to PCa, discuss their prospective relevance for predictive and prognostic evaluations, and outline the prevailing obstacles in quantitatively evaluating neovascularization via histopathological examinations.

Up-to-date molecular medicine strategies for management of ocular surface neovascularization

Ocular surface neovascularization and its resulting pathological changes significantly alter corneal refraction and obstruct the light path to the retina, and hence is a major cause of vision loss. Various factors such as infection, irritation, trauma, dry eye, and ocular surface surgery trigger neovascularization via angiogenesis and lymphangiogenesis dependent on VEGF-related and alternative mechanisms. Recent advances in antiangiogenic drugs, nanotechnology, gene therapy, surgical equipment and techniques, animal models, and drug delivery strategies have provided a range of novel therapeutic options for the treatment of ocular surface neovascularization. In this review article, we comprehensively discuss the etiology and mechanisms of corneal neovascularization and other types of ocular surface neovascularization, as well as emerging animal models and drug delivery strategies that facilitate its management.

Macrophage-Derived Cathepsin S Remodels the Extracellular Matrix to Promote Liver Fibrogenesis

BACKGROUND & AIMS

Liver fibrosis is an intrinsic wound-healing response to chronic injury and the major cause of liver-related morbidity and mortality worldwide. However, no effective diagnostic or therapeutic strategies are available, owing to its poorly characterized molecular etiology. We aimed to elucidate the mechanisms underlying liver fibrogenesis.

METHODS

We performed a quantitative proteomic analysis of clinical fibrotic liver samples to identify dysregulated proteins. Further analyses were performed on the sera of 164 patients with liver fibrosis. Two fibrosis mouse models and several biochemical experiments were used to elucidate liver fibrogenesis.

RESULTS

We identified cathepsin S (CTSS) up-regulation as a central node for extracellular matrix remodeling in the human fibrotic liver by proteomic screening. Increased serum CTSS levels efficiently predicted liver fibrosis, even at an early stage. Secreted CTSS cleaved collagen 18A1 at its C-terminus, releasing endostatin peptide, which directly bound to and activated hepatic stellate cells via integrin α5β1 signaling, whereas genetic ablation of Ctss remarkably suppressed liver fibrogenesis via endostatin reduction in vivo. Further studies identified macrophages as the main source of hepatic CTSS, and splenectomy effectively attenuated macrophage infiltration and CTSS expression in the fibrotic liver. Pharmacologic inhibition of CTSS ameliorated liver fibrosis progression in the mouse models.

CONCLUSIONS

CTSS functions as a novel profibrotic factor by remodeling extracellular matrix proteins and may represent a promising target for the diagnosis and treatment of liver fibrosis.

ANG2 Blockade Diminishes Proangiogenic Cerebrovascular Defects Associated With Models of Hereditary Hemorrhagic Telangiectasia

BACKGROUND

Hereditary hemorrhagic telangiectasia (HHT) is a vascular disorder characterized by arteriovenous malformations and blood vessel enlargements. However, there are no effective drug therapies to combat arteriovenous malformation formation in patients with HHT. Here, we aimed to address whether elevated levels of ANG2 (angiopoietin-2) in the endothelium is a conserved feature in mouse models of the 3 major forms of HHT that could be neutralized to treat brain arteriovenous malformations and associated vascular defects. In addition, we sought to identify the angiogenic molecular signature linked to HHT.

METHODS

Cerebrovascular defects, including arteriovenous malformations and increased vessel calibers, were characterized in mouse models of the 3 common forms of HHT using transcriptomic and dye injection labeling methods.

RESULTS

Comparative RNA sequencing analyses of isolated brain endothelial cells revealed a common, but unique proangiogenic transcriptional program associated with HHT. This included a consistent upregulation in cerebrovascular expression of ANG2 and downregulation of its receptor Tyr kinase with Ig and EGF homology domains (TIE2/TEK) in HHT mice compared with controls. Furthermore, in vitro experiments revealed TEK signaling activity was hampered in an HHT setting. Pharmacological blockade of ANG2 improved brain vascular pathologies in all HHT models, albeit to varying degrees. Transcriptomic profiling further indicated that ANG2 inhibition normalized the brain vasculature by impacting a subset of genes involved in angiogenesis and cell migration processes.

CONCLUSIONS

Elevation of ANG2 in the brain vasculature is a shared trait among the mouse models of the common forms of HHT. Inhibition of ANG2 activity can significantly limit or prevent brain arteriovenous malformation formation and blood vessel enlargement in HHT mice. Thus, ANG2-targeted therapies may represent a compelling approach to treat arteriovenous malformations and vascular pathologies related to all forms of HHT.

Identification of unique α4 chain structure and conserved antiangiogenic activity of α3NC1 type IV collagen in zebrafish

BACKGROUND

Type IV collagen is an abundant component of basement membranes in all multicellular species and is essential for the extracellular scaffold supporting tissue architecture and function. Lower organisms typically have two type IV collagen genes, encoding α1 and α2 chains, in contrast with the six genes in humans, encoding α1-α6 chains. The α chains assemble into trimeric protomers, the building blocks of the type IV collagen network. The detailed evolutionary conservation of type IV collagen network remains to be studied.

RESULTS

We report on the molecular evolution of type IV collagen genes. The zebrafish α4 non-collagenous (NC1) domain, in contrast with its human ortholog, contains an additional cysteine residue and lacks the M93 and K211 residues involved in sulfilimine bond formation between adjacent protomers. This may alter α4 chain interactions with other α chains, as supported by temporal and anatomic expression patterns of collagen IV chains during the zebrafish development. Despite the divergence between zebrafish and human α3 NC1 domain (endogenous angiogenesis inhibitor, Tumstatin), the zebrafish α3 NC1 domain exhibits conserved antiangiogenic activity in human endothelial cells.

CONCLUSIONS

Our work supports type IV collagen is largely conserved between zebrafish and humans, with a possible difference involving the α4 chain.

Cartilage-Related Collagens in Osteoarthritis and Rheumatoid Arthritis: From Pathogenesis to Therapeutics

Collagens serve essential mechanical functions throughout the body, particularly in the connective tissues. In articular cartilage, collagens provide most of the biomechanical properties of the extracellular matrix essential for its function. Collagen plays a very important role in maintaining the mechanical properties of articular cartilage and the stability of the ECM. Noteworthily, many pathogenic factors in the course of osteoarthritis and rheumatoid arthritis, such as mechanical injury, inflammation, and senescence, are involved in the irreversible degradation of collagen, leading to the progressive destruction of cartilage. The degradation of collagen can generate new biochemical markers with the ability to monitor disease progression and facilitate drug development. In addition, collagen can also be used as a biomaterial with excellent properties such as low immunogenicity, biodegradability, biocompatibility, and hydrophilicity. This review not only provides a systematic description of collagen and analyzes the structural characteristics of articular cartilage and the mechanisms of cartilage damage in disease states but also provides a detailed characterization of the biomarkers of collagen production and the role of collagen in cartilage repair, providing ideas and techniques for clinical diagnosis and treatment.

Redifferentiated cardiomyocytes retain residual dedifferentiation signatures and are protected against ischemic injury

Cardiomyocyte proliferation and dedifferentiation have fueled the field of regenerative cardiology in recent years, whereas the reverse process of redifferentiation remains largely unexplored. Redifferentiation is characterized by the restoration of function lost during dedifferentiation. Previously, we showed that ERBB2-mediated heart regeneration has these two distinct phases: transient dedifferentiation and redifferentiation. Here we survey the temporal transcriptomic and proteomic landscape of dedifferentiation-redifferentiation in adult mouse hearts and reveal that well-characterized dedifferentiation features largely return to normal, although elements of residual dedifferentiation remain, even after the contractile function is restored. These hearts appear rejuvenated and show robust resistance to ischemic injury, even 5 months after redifferentiation initiation. Cardiomyocyte redifferentiation is driven by negative feedback signaling and requires LATS1/2 Hippo pathway activity. Our data reveal the importance of cardiomyocyte redifferentiation in functional restoration during regeneration but also protection against future insult, in what could lead to a potential prophylactic treatment against ischemic heart disease for at-risk patients.

Damaged collagen detected by collagen hybridizing peptide as efficient diagnosis marker for early hepatic fibrosis

Liver fibrosis is characterized by excessive synthesis and deposition of extracellular matrix (ECM) in liver tissues. However, it still has been lacking of early detection and diagnosis methods. The collagen hybridizing peptide (CHP) is a novel synthetic peptide that enables detection of collagen damage and tissue remodeling. Here, we showed that obvious CHP-positive staining could be detected in the liver while given CCl₄ for only 3 days, which was significantly enhanced while given CCl₄ for 7 days. However, H&E staining showed no significant changes in fibrous tissue, and sirius red-positive staining could only be observed while given CCl₄ for 14 days. Moreover, CHP-positive staining enhanced initially at portal area which further extended into the hepatic lobule, which was increased more significantly than sirius red-positive staining in the model of 10 and 14 days. Further proteomic analysis of CHP-positive staining revealed that pathways associated with ECM remodeling were significantly increased, while retinol metabolism was downregulated. Meanwhile, proteins enriched in cellular gene transcription and signal transduction involved in fibrogenesis were also upregulated, suggesting that fibrosis occurred in CHP-positive staining. Our study provided evidence that CHP could detect the collagen damage in liver, which might be an efficient indicator for the diagnosis of liver fibrosis at a very early stage.

Vascularized Tissue Organoids

Tissue organoids hold enormous potential as tools for a variety of applications, including disease modeling and drug screening. To effectively mimic the native tissue environment, it is critical to integrate a microvasculature with the parenchyma and stroma. In addition to providing a means to physiologically perfuse the organoids, the microvasculature also contributes to the cellular dynamics of the tissue model via the cells of the perivascular niche, thereby further modulating tissue function. In this review, we discuss current and developing strategies for vascularizing organoids, consider tissue-specific vascularization approaches, discuss the importance of perfusion, and provide perspectives on the state of the field.

Secretome analysis reveals reduced expression of COL4A2 in hypoxic cancer-associated fibroblasts with a tumor-promoting function in gastric cancer

BACKGROUND

Cancer-associated fibroblasts (CAFs) are major components of the tumor microenvironment (TME). Hypoxic TME is known to promote tumor progression. However, how a hypoxic condition regulates CAFs remains elusive.

METHODS

To investigate the underlying mechanism involved in the regulation of gastric cancer (GC) progression by hypoxic CAFs, we performed secretome profiling. Normoxic or hypoxic CAFs conditioned media (CM) were filter-concentrated and in-gel trypsin digested. Resulting peptides were analyzed with LC-MS/MS.

RESULTS

We observed that CM derived from hypoxic CAFs could promote migration of a panel of GC cell lines (AGS, SNU668, SNU638). Mass spectrometry analysis of hypoxic or normoxic CAFs CM identified 1595 proteins, of which 19 proteins (10 upregulated and 9 downregulated) were differentially expressed in the hypoxic secretome. We focused on COL4A2, whose expression was significantly decreased in hypoxic CAFs in HIF-1α-independent manner. Silencing of COL4A2 expression in normoxic CAFs phenocopied the effect of hypoxic CAFs in promoting GC cell migration.

CONCLUSIONS

The reduced expression of COL4A2 in a hypoxic environment might be associated with the tumor-promoting role of hypoxic CAFs in GC.

Recombinant Human Arresten and Canstatin Inhibit Angiogenic Behaviors of HUVECs via Inhibiting the PI3K/Akt Signaling Pathway

Angiogenetic inhibitors are crucial in tumor therapy, and endogenous angiogenesis inhibitors have attracted considerable attention due to their effectiveness, safety, and multi-targeting ability. Arresten and canstatin, which have anti-angiogenesis effects, are the c-terminal fragments of the α1 and α2 chains of type IV collagen, respectively. In this study, human arresten and canstatin were recombinantly expressed in Escherichia coli (E. coli), and their effects on the proliferation, migration and tube formation of human umbilical vein endothelial cells (HUVECs) were evaluated. Regarding the cell cycle distribution test and 5-ethynyl-2′-deoxyuridine (EdU) assays, arresten and canstatin could repress the proliferation of HUVECs at a range of concentrations. Transwell assay indicated that the migration of HUVECs was significantly decreased in the presence of arresten and canstatin, while tube formation assays suggested that the total tube length and junction number of HUVECs were significantly inhibited by these two proteins; moreover, they could also reduce the expression of vascular endothelial growth factor (VEGF) and the phosphorylation levels of PI3K and Akt, which indicated that the activation of the 3-kinase/serine/threonine-kinase (PI3K/Akt) signaling pathway was inhibited. These findings may have important implications for the soluble recombinant expression of human arresten and canstatin, and for the related therapy of cancer.

The Role of Extracellular Matrix Proteins in Breast Cancer

The extracellular matrix is a structure composed of many molecules, including fibrillar (types I, II, III, V, XI, XXIV, XXVII) and non-fibrillar collagens (mainly basement membrane collagens: types IV, VIII, X), non-collagenous glycoproteins (elastin, laminin, fibronectin, thrombospondin, tenascin, osteopontin, osteonectin, entactin, periostin) embedded in a gel of negatively charged water-retaining glycosaminoglycans (GAGs) such as non-sulfated hyaluronic acid (HA) and sulfated GAGs which are linked to a core protein to form proteoglycans (PGs). This highly dynamic molecular network provides critical biochemical and biomechanical cues that mediate the cell–cell and cell–matrix interactions, influence cell growth, migration and differentiation and serve as a reservoir of cytokines and growth factors’ action. The breakdown of normal ECM and its replacement with tumor ECM modulate the tumor microenvironment (TME) composition and is an essential part of tumorigenesis and metastasis, acting as key driver for malignant progression. Abnormal ECM also deregulate behavior of stromal cells as well as facilitating tumor-associated angiogenesis and inflammation. Thus, the tumor matrix modulates each of the classically defined hallmarks of cancer promoting the growth, survival and invasion of the cancer. Moreover, various ECM-derived components modulate the immune response affecting T cells, tumor-associated macrophages (TAM), dendritic cells and cancer-associated fibroblasts (CAF). This review article considers the role that extracellular matrix play in breast cancer. Determining the detailed connections between the ECM and cellular processes has helped to identify novel disease markers and therapeutic targets.

The role of basement membranes in cardiac biology and disease

Basement membranes are highly specialised extracellular matrix structures that within the heart underlie endothelial cells and surround cardiomyocytes and vascular smooth muscle cells. They generate a dynamic and structurally supportive environment throughout cardiac development and maturation by providing physical anchorage to the underlying interstitium, structural support to the tissue, and by influencing cell behaviour and signalling. While this provides a strong link between basement membrane dysfunction and cardiac disease, the role of the basement membrane in cardiac biology remains under-researched and our understanding regarding the mechanistic interplay between basement membrane defects and their morphological and functional consequences remain important knowledge-gaps. In this review we bring together emerging understanding of basement membrane defects within the heart including in common cardiovascular pathologies such as contractile dysfunction and highlight some key questions that are now ready to be addressed.

Prolyl 3-Hydroxylase 2 Is a Molecular Player of Angiogenesis

Prolyl 3-hydroxylase 2 (P3H2) catalyzes the post-translational formation of 3-hydroxyproline on collagens, mainly on type IV. Its activity has never been directly associated to angiogenesis. Here, we identified P3H2 gene through a deep-sequencing transcriptome analysis of human umbilical vein endothelial cells (HUVECs) stimulated with vascular endothelial growth factor A (VEGF-A). Differently from many previous studies we carried out the stimulation not on starved HUVECs, but on cells grown to maintain the best condition for their in vitro survival and propagation. We showed that P3H2 is induced by VEGF-A in two primary human endothelial cell lines and that its transcription is modulated by VEGF-A/VEGF receptor 2 (VEGFR-2) signaling pathway through p38 mitogen-activated protein kinase (MAPK). Then, we demonstrated that P3H2, through its activity on type IV Collagen, is essential for angiogenesis properties of endothelial cells in vitro by performing experiments of gain- and loss-of-function. Immunofluorescence studies showed that the overexpression of P3H2 induced a more condensed status of Collagen IV, accompanied by an alignment of the cells along the Collagen IV bundles, so towards an evident pro-angiogenic status. Finally, we found that P3H2 knockdown prevents pathological angiogenesis in vivo, in the model of laser-induced choroid neovascularization. Together these findings reveal that P3H2 is a new molecular player involved in new vessels formation and could be considered as a potential target for anti-angiogenesis therapy.

Proteomic analysis of body wall and coelomic fluid in Sipunculus nudus

In order to make clear the protein compositions of Sipunculus nudus and investigate its immune-related proteins, proteomic analysis was performed on body wall and coelomic fluid of Sipunculus nudus. A total of 1659 proteins were identified, and 539 proteins were differentially expressed in the coelomic fluid compared to those in the body wall, of which 415 proteins were up-regulated while 124 proteins were down-regulated. Gene Ontology (GO) analysis showed that the GO terms involved in the two parts of Sipunculus nudus were similar, with metabolic processes, catalytic activity and cell occupying the top categories of biological process, molecular function and cellular component, respectively. KEGG pathway analysis showed that 49 pathways in body wall and 48 in coelomic fluid were mapped respectively, and these pathways were mainly related to cellular processes, environmental information processing, genetic information processing and metabolism. The COG analysis showed that 757 proteins from body wall and 889 from coelomic fluid were classified into 26 COG categories, respectively. Pfam annotation revealed the mainly immune-related proteins contained in Sipunculus nudus, such as insulin-like growth factor binding protein, catalase, basement membrane proteoglycan, titin. Our research provides the first proteomic information of Sipunculus nudus, which contributes to the study of functional proteins in Sipunculus nudus and is of great significance for the application of Sipunculus nudus in functional foods and medicines.

Differential expression of COL4A3 and collagen in upward and downward progressing types of nasopharyngeal carcinoma

Upward (local growth and invasion of the base of skull), downward (distant metastasis) and mixed progressing types of nasopharyngeal carcinoma (NPC) have been identified and are distinctly different with respect to clinical symptoms, therapeutic strategies and prognosis. The present study aimed to identify the genetic difference and collagen expression levels in the upward and downward progressing types of NPC. Whole exon sequencing (WES) was used to detect genes differentially mutated between the upward and downward progressing types of NPC. Collagen deposition in the upward and downward progressing types of NPC was determined using Masson trichromatic staining, while the protein expression level of COL4A3 was detected using immunohistochemistry. Survival analysis was also performed using the Kaplan-Meier Plotter database to examine the role of COL4A3 expression level in the prognosis of head and neck squamous cell carcinoma. Knockdown of COL4A3 was performed using short interfering (si)RNA-COL4A3 in a 5-8F NPC cell line. Reverse transcription-quantitative PCR and western blot analyses were utilized to analyze the mRNA and protein expression levels of COL4A3, respectively. The roles of COL4A3 in the migration and invasion of the 5-8F cell line were examined using wound-healing Transwell and Matrigel assays, respectively. A total of 21 genes were differentially mutated between the upward and downward progressing types of NPC. The COL4A3 was investigated further, as it was found to be associated with extracellular matrix deposition and cancer metastasis. The COL4A3 gene was markedly downregulated in the downward progressing type compared with that in the upward progressing type (2.161±1.306 vs. 5.077±3.619; P<0.05). In addition, the deposition of collagen in the downward progressing type was also significantly decreased compared with that in the upward progressing type (5.63±6.83 vs. 10.94±9.60; P<0.05). Kaplan-Meier analysis indicated that high expression level of COL4A3 was positively associated with a favorable prognosis of head and neck squamous cell carcinoma (HR, 0.69; 95% CI, 0.49- 0.97; P=0.031). To confirm the role of COL4A3, the expression level of COL4A3 was knocked down using siRNA in the 5-8F cell line and the results showed that the invasion and migration was significantly increased when the expression of COL4A3 was inhibited (P<0.0001). In conclusion, the gene mutation patterns were significantly different between the upward and downward progressing types of NPC. In addition, the expression level of the COL4A3 gene was decreased in the downward progressing type, which might promote NPC metastasis through the downregulation of extracellular collagen expression.

Relapse of pathological angiogenesis: functional role of the basement membrane and potential treatment strategies

Blinding eye diseases such as corneal neovascularization, proliferative diabetic retinopathy, and age-related macular degeneration are driven by pathological angiogenesis. In cancer, angiogenesis is key for tumor growth and metastasis. Current antiangiogenic treatments applied clinically interfere with the VEGF signaling pathway-the main angiogenic pathway-to inhibit angiogenesis. These treatments are, however, only partially effective in regressing new pathologic vessels, and the disease relapses following cessation of treatment. Moreover, the relapse of pathological angiogenesis can be rapid, aggressive and more difficult to treat than angiogenesis in the initial phase. The manner in which relapse occurs is poorly understood; however, recent studies have begun to shed light on the mechanisms underlying the revascularization process. Hypotheses have been generated to explain the rapid angiogenic relapse and increased resistance of relapsed disease to treatment. In this context, the present review summarizes knowledge of the various mechanisms of disease relapse gained from different experimental models of pathological angiogenesis. In addition, the basement membrane-a remnant of regressed vessels-is examined in detail to discuss its potential role in disease relapse. Finally, approaches for gaining a better understanding of the relapse process are discussed, including prospects for the management of relapse in the context of disease.

[Development of basic research toward clinical application of cleaved fragment of type IV collagen]

Basement membrane is a dense sheet-like extracellular matrix (ECM), which separates cells from surrounding interstitium. Type IV collagen is a major component of basement membrane and three of six α chains (namely α1-α6 chains) form a triple-helix structure. Recently, endogenous bioactive factors called "matricryptins" or "matrikines", which are produced by degrading and cleaving C-terminal domain of type IV collagen, attract attentions as a novel therapeutic target or a candidate for biomarkers. In all type IV collagens, matricryptins called arresten (α1 chain), canstatin (α2), tumstatin (α3), tetrastatin (α4), pentastatin (α5), and hexastatin (α6), have been identified. The type IV collagen-derived matricryptins have been previously studied as new therapeutic targets for neoplastic diseases since they exert anti-angiogenic and/or anti-tumor effects. On the other hand, we have recently demonstrated the cardioprotective effects of matricryptins in addition to the altered expression levels in cardiac diseases. In this review, we introduce the results of fundamental studies for the type IV collagen-derived matricryptins in various diseases, such as neoplastic diseases and cardiac diseases, and discuss the potential clinical application as novel therapeutic agents and biomarkers.

Extracellular Matrix Remodeling in Chronic Liver Disease

PURPOSE OF THE REVIEW

This review aims to summarize the current knowledge of the extracellular matrix remodeling during hepatic fibrosis. We discuss the diverse interactions of the extracellular matrix with hepatic cells and the surrounding matrix in liver fibrosis, with the focus on the molecular pathways and the mechanisms that regulate extracellular matrix remodeling.

RECENT FINDINGS

The extracellular matrix not only provides structure and support for the cells, but also controls cell behavior by providing adhesion signals and by acting as a reservoir of growth factors and cytokines.

SUMMARY

Hepatic fibrosis is characterized by an excessive accumulation of extracellular matrix. During fibrogenesis, the natural remodeling process of the extracellular matrix varies, resulting in the excessive accumulation of its components, mainly collagens. Signals released by the extracellular matrix induce the activation of hepatic stellate cells, which are the major source of extracellular matrix and most abundant myofibroblasts in the liver.

GRAPHICAL ABSTRACT

Profiling and targeting connective tissue remodeling in autoimmunity - A novel paradigm for diagnosing and treating chronic diseases

Connective tissue (ConT) remodeling is an essential process in tissue regeneration, where a balanced replacement of old tissue by new tissue occurs. This balance is disturbed in chronic diseases, often autoimmune diseases, usually resulting in the buld up of fibrosis and a gradual loss of organ function. During progression of liver, lung, skin, heart, joint, skeletal and kidney diseasesboth ConT formation and degradation are elevated, which is tightly linked to immune cell activation and a loss of specific cell types and extracellular matrix (ECM) structures that are required for normal organ function. Here, we address the balance of key general and organ specific components of the ECM during homeostasis and in disease, with a focus on collagens, which are emerging as both structural and signaling molecules harbouring neoepitopes and autoantigens that are released during ConT remodeling. Specific collagen molecular signatures of ConT remodeling are linked to disease activity and stage, and to prognosis across different organs. These signatures accompany and further drive disease progression, and often become detectable before clinical disease manifestation (illness). Recent advances allow to quantify and define the nature of ConT remodeling via blood-based assays that measure the levels of well-defined collagen fragments, reflecting different facets of ConT formation and degradation, and associated immunological processes. These novel serum assays are becoming important tools of precision medicine, to detect various chronic and autoimmune diseases before their clinical manifestation, and to non-invasively monitor the efficacy of a broad range of pharmacological interventions.

Regulation of Obesity by Antiangiogenic Herbal Medicines

Obesity is the result of an energy imbalance caused by an increased ratio of caloric intake to energy expenditure. In conjunction with obesity, related metabolic disorders, such as dyslipidemia, atherosclerosis, and type 2 diabetes, have become global health problems. Obesity progression is thought to be associated with angiogenesis and extracellular matrix (ECM) remodeling. Angiogenesis occurs in growing adult adipose tissues, which are similar to neoplastic tissues. Adipose tissue is highly vascularized, and each adipocyte is nourished by an extensive capillary network. Adipocytes produce proangiogenic factors, such as vascular endothelial growth factor A and fibroblast growth factor 2, which promote neovascularization within the adipose tissue. Furthermore, matrix metalloproteinases (MMPs), including MMP-2 and MMP-9, play important roles in adipose tissue development and microvessel maturation by modifying the ECM. Thus, modulation of angiogenesis and MMP activity provides a promising therapeutic approach for controlling human obesity and its related disorders. Over the past decade, there has been a great increase in the use of alternative treatments, such as herbal remedies, for these diseases. This review will focus on the role of angiogenesis in adipose tissue growth and the regulation of obesity by antiangiogenic herbal medicines.

Angiogenesis Inhibition by a Short 13 Amino Acid Peptide Sequence of Tetrastatin, the α4(IV) NC1 Domain of Collagen IV

Angiogenesis is defined as the formation of new capillaries by sprouting from the pre-existing microvasculature. It occurs in physiological and pathological processes particularly in tumor growth and metastasis. α1, α2, α3, and α6 NC1 domains from type IV collagen were reported to inhibit tumor angiogenesis. We previously demonstrated that the α4 NC1 domain from type IV collagen, named Tetrastatin, inhibited tumor growth in a mouse melanoma model. The inhibitory activity was located in a 13 amino acid sequence named QS-13. In the present paper, we demonstrate that QS-13 decreases VEGF-induced-angiogenesis in vivo using the Matrigel plug model. Fluorescence molecular tomography allows the measurement of a 65% decrease in Matrigel plug angiogenesis following QS-13 administration. The results are confirmed by CD31 microvessel density analysis on Matrigel plug slices. QS-13 peptide decreases Human Umbilical Vein Endothelial Cells (HUVEC) migration and pseudotube formation in vitro. Relevant QS-13 conformations were obtained from molecular dynamics simulations and docking. A putative interaction of QS-13 with α₅β₁ integrin was investigated. The interaction was confirmed by affinity chromatography, solid phase assay, and surface plasmon resonance. QS-13 binding site on α₅β₁ integrin is located in close vicinity to the RGD binding site, as demonstrated by competition assays. Collectively, our results suggest that QS-13 exhibits a mighty anti-angiogenic activity that could be used in cancer treatment and other pathologies with excessive angiogenesis such as hemangioma, psoriasis or diabetes.

Engineering a collagen matrix for cell-instructive regenerative angiogenesis

Engineering an angiogenic material for regenerative medicine requires knowledge of native extracellular matrix remodeling by cellular processes in angiogenesis. Vascularization remains a key challenge in the field of tissue engineering, one that can be mitigated by developing platforms conducive to guiding dynamic cell-matrix interactions required for new vessel formation. In this review, we highlight nuanced processes of angiogenesis and demonstrate how materials engineering is being used to interface with dynamic type I collagen remodeling, Notch and VEGF signaling, cell migration, and tissue morphogenesis. Because α1(I)-collagen is secreted by endothelial tip cells during sprouting angiogenesis and required for migration, collagen is a very useful natural biomaterial and its angiogenic modifications are described. The balance between collagen types I and IV via secretion and degradation is tightly controlled by proteinases and other cell types that are capable of internalizing collagen to maintain tissue integrity. Thus, we provide examples in skin and cardiac tissue engineering of collagen tailoring in diverse cellular microenvironments for tissue regeneration. As our understanding of how to drive collagen remodeling and cellular phenotype through angiogenic pathways grows, our capabilities to model and manipulate material systems must continue to expand to develop novel applications for wound healing, angiogenic therapy, and regenerative medicine.

The liver fibrosis niche: Novel insights into the interplay between fibrosis-composing mesenchymal cells, immune cells, endothelial cells, and extracellular matrix

Liver fibrosis is a hepatic wound-healing response caused by chronic liver diseases that include viral hepatitis, alcoholic liver disease, non-alcoholic steatohepatitis, and cholestatic liver disease. Liver fibrosis eventually progresses to cirrhosis that is histologically characterized by an abnormal liver architecture that includes distortion of liver parenchyma, formation of regenerative nodules, and a massive accumulation of extracellular matrix (ECM). Despite intensive investigations into the underlying mechanisms of liver fibrosis, developments of anti-fibrotic therapies for liver fibrosis are still unsatisfactory. Recent novel experimental approaches, such as single-cell RNA sequencing and proteomics, have revealed the heterogeneity of ECM-producing cells (mesenchymal cells) and ECM-regulating cells (immune cells and endothelial cells). These approaches have accelerated the identification of fibrosis-specific subpopulations among these cell types. The ECM also consists of heterogenous components. Their production, degradation, deposition, and remodeling are dynamically regulated in liver fibrosis, further affecting the functions of cells responsible for fibrosis. These cellular and ECM elements cooperatively form a unique microenvironment: a fibrotic niche. Understanding the complex interplay between these elements could lead to a better understanding of underlying fibrosis mechanisms and to the development of effective therapies.

Collagen analysis with mass spectrometry

Mass spectrometry-based techniques can be applied to investigate collagen with respect to identification, quantification, supramolecular organization, and various post-translational modifications. The continuous interest in collagen research has led to a shift from techniques to analyze the physical characteristics of collagen to methods to study collagen abundance and modifications. In this review, we illustrate the potential of mass spectrometry for in-depth analyses of collagen.

Evaluation of collagen derived antiangiogenic factors and matrix metalloproteinases in anterior lens epithelial cells of pediatric eyes with persistent fetal vasculature

Purpose:

To measure levels of collagen-derived antiangiogenic factors (arresten, canstatin, tumstatin, endostatin) and matrix metalloproteinases (MMP-2 and MMP-9) in anterior lens epithelial cells (LECs) and anterior capsules of children with cataract and persistent fetal vasculature (PFV) as cases and cataract without PFV as controls.

Methods:

Anterior capsules harboring LECs were collected from pediatric cataract patients with (n = 13) and without PFV (n = 13) during surgery. Samples were immediately subjected to RNA extraction and cDNA preparation. Quantitative real time PCR was performed to determine the mRNA levels of antiangiogenic factors and matrix metalloproteinases. GAPDH (Glyceraldehyde 3-Phosphate Dehydrogenase) and β Actin were used as the housekeeping control. The mRNA levels were expressed as a ratio, using the delta-delta method for comparing the relative expression results between controls and cases. The non-parametric Mann-Whitney U test was applied for statistical evaluation. P values < 0.05 were statistically significant.

Results:

The relative mRNA levels of arresten, canstatin, tumstatin, endostatin, MMP-2 and MMP-9 in cases were 6.20E-03 ± 0.003, 1.49E-01 ± 0.02, 1.70E-01 ± 0.007, 3.20E-03 ± 0.003, 1.11E-03 ± 0.0009 and 3.72E-04 ± 0.0001. The mRNA levels of arresten was 1.6 times lower (P = 0.01) while mRNA levels of MMP-2, tumstatin and canstatin were 4, 2.5, and 2.3 times higher in cases than in controls. No change was observed in mRNA levels of MMP-9 and endostatin (P = 0.82).

Conclusion:

A significant difference in the levels of arresten, canstatin, tumstatin, and MMP-2 was found in LECs with PFV.

Collagen biology and non-invasive biomarkers of liver fibrosis

There is an unmet need for high-quality liquid biomarkers that can safely and reproducibly predict the stage of fibrosis and the outcomes of chronic liver disease (CLD). The requirement for such markers has intensified because of the high global prevalence of diseases such as non-alcoholic fatty liver disease (NAFLD). In particular, there is a need for diagnostic and prognostic tools, as well as predictive biomarkers that reflect the efficacy of interventions, as described by the BEST criteria (Biomarkers, EndpointS, and other Tools Resource). This review covers the various liver collagens, their functional role in tissue homeostasis and delineates the common nomenclature for biomarkers based on BEST criteria. It addresses the common confounders affecting serological biomarkers, and describes defined collagen epitope biomarkers that originate from the dynamic processes of extracellular matrix (ECM) remodelling during liver injury.

Osteopontin Upregulates Col IV Expression by Repressing miR-29a in Human Retinal Capillary Endothelial Cells

Abnormal synthesis of extracellular matrix (ECM), especially collagen type IV (Col IV), in human retinal capillary endothelial cells (HRCECs) and resultant basement membrane (BM) thickening is the most prominent and characteristic feature of early diabetic retinopathy (DR). Osteopontin (OPN) has been shown to play an important role in the pathogenesis of DR and specifically, found to be critically involved in diabetic nephropathy, as it can upregulate many factors, like collagen IV. However, the precise role of OPN in the pathogenesis of DR and the underlying mechanisms remain unclear. In this study, 51 differentially expressed microRNAs (miRNAs; 42 miRNAs upregulated and 9 miRNAs downregulated) were first identified in retina of streptozotocin (STZ)-induced diabetic mice with DR. Among these miRNAs, we identified miRNA (miR)-29a as a prominent miRNA that targeted and directly downregulated Col IV expression through database prediction and dual-luciferase reporter assay, which was further confirmed in HRCECs using miR-29a mimic, miR-29a inhibitor, and pre-miR-29a transfection. Furthermore, OPN upregulated Col IV expression via a miR-29a-repressed pathway in HRCECs. Taken together, these results provided a miR-29a-repressing mechanism through which OPN plays roles in abnormal synthesis of Col IV in HRCECs and resultant BM thickening, contributing to the pathogenesis of DR.

Role of Endogenous Regulators of Hem- And Lymphangiogenesis in Corneal Transplantation

Under normal conditions, the cornea, being the transparent “windscreen” of the eye, is free of both blood and lymphatic vessels. However, various diseases of the eye, like infections, can interfere with the balance between promoting and inhibiting factors, which leads to ingrowth of blood and lymphatic vessels. The newly formed lymphatic vessels increase the risk of graft rejection after subsequent corneal transplantation. Corneal transplantation is one of the most commonly performed transplantations worldwide, with more than 40,000 surgeries per year in Europe. To date, various anti-hem- and anti-lymphangiogenic treatment strategies have been developed specifically for the corneal vascular endothelial growth factor (VEGF) pathway. Currently, however, no treatment strategies are clinically available to specifically modulate lymphangiogenesis. In this review, we will give an overview about endogenous regulators of hem- and lymphangiogenesis and discuss potential new strategies for targeting pathological lymphangiogenesis. Furthermore, we will review recently identified modulators and demonstrate that the cornea is a suitable model for the identification of novel endogenous modulators of lymphangiogenesis. The identification of novel modulators of lymphangiogenesis and a better understanding of the signaling pathways involved will contribute to the development of new therapeutic targets for the treatment of pathological lymphangiogenesis. This, in turn, will improve graft rejection, not only for the cornea.

Antiangiogenic Effects of Coumarins against Cancer: From Chemistry to Medicine

Angiogenesis, the process of formation and recruitment of new blood vessels from pre-existing vessels, plays an important role in the development of cancer. Therefore, the use of antiangiogenic agents is one of the most critical strategies for the treatment of cancer. In addition, the complexity of cancer pathogenicity raises the need for multi-targeting agents. Coumarins are multi-targeting natural agents belonging to the class of benzopyrones. Coumarins have several biological and pharmacological effects, including antimicrobial, antioxidant, anti-inflammation, anticoagulant, anxiolytic, analgesic, and anticancer properties. Several reports have shown that the anticancer effect of coumarins and their derivatives are mediated through targeting angiogenesis by modulating the functions of vascular endothelial growth factor as well as vascular endothelial growth factor receptor 2, which are involved in cancer pathogenesis. In the present review, we focus on the antiangiogenic effects of coumarins and related structure-activity relationships with particular emphasis on cancer.

Parenchymal pericytes are not the major contributor of extracellular matrix in the fibrotic scar after stroke in male mice

Scar formation after injury of the brain or spinal cord is a common event. While glial scar formation by astrocytes has been extensively studied, much less is known about the fibrotic scar, in particular after stroke. Platelet‐derived growth factor receptor ß‐expressing (PDGFRß⁺) pericytes have been suggested as a source of the fibrotic scar depositing fibrous extracellular matrix (ECM) proteins after detaching from the vessel wall. However, to what extent these parenchymal PDGFRß⁺ cells contribute to the fibrotic scar and whether targeting these cells affects fibrotic scar formation in stroke is still unclear. Here, we utilize male transgenic mice that after a permanent middle cerebral artery occlusion stroke model have a shift from a parenchymal to a perivascular location of PDGFRß⁺ cells due to the loss of regulator of G‐protein signaling 5 in pericytes. We find that only a small fraction of parenchymal PDGFRß⁺ cells co‐label with type I collagen and fibronectin. Consequently, a reduction in parenchymal PDGFRß⁺ cells by ca. 50% did not affect the overall type I collagen or fibronectin deposition after stroke. The redistribution of PDGFRß⁺ cells to a perivascular location, however, resulted in a reduced thickening of the vascular basement membrane and changed the temporal dynamics of glial scar maturation after stroke. We demonstrate that parenchymal PDGFRß⁺ cells are not the main contributor to the fibrotic ECM, and therefore targeting these cells might not impact on fibrotic scar formation after stroke.

Mechanisms of vascular permeability and remodeling associated with hemarthrosis in factor VIII-deficient mice

BACKGROUND

Vascular remodeling associated with hemophilic arthropathy (HA) may contribute to bleed propagation, but the mechanisms remain poorly understood.

OBJECTIVES

To explore molecular mechanisms of HA and the effects of hemostasis correction on synovial vascular remodeling after joint injury in hypocoagulable mice.

METHODS

Factor VIII (FVIII)-deficient mice +/- FVIII treatment and hypocoagulable wild-type mice (Hypo BALB/c) were subjected to subpatellar puncture. Hypo BALB/c mice were treated with warfarin and anti-FVIII before injury, after which warfarin was continued for 2 weeks or reversed +/- continuous anti-FVIII until harvest. Synovial vascularity was analyzed at baseline and 2 to 4 weeks post injury by histology, musculoskeletal ultrasound with power Doppler (microvascular flow), and Evans blue extravasation (vascular permeability). Synovial gene expression and systemic markers of vascular collagen turnover were studied in FVIII-deficient mice by RNA sequencing and enzyme-linked immunosorbent assay.

RESULTS

Vascular changes occurred in FVIII-deficient and Hypo BALB/c mice after injury with minimal effect of hemostasis correction. Increased vascular permeability was only significant in FVIII-deficient mice, who exhibited more pronounced vascular remodeling than Hypo BALB/c mice despite similar bleed volumes. FVIII-deficient mice exhibited a strong transcriptional response in synovium that was only partially affected by FVIII treatment and involved genes relating to angiogenesis and extracellular matrix remodeling, with vascular collagen turnover markers detected systemically.

CONCLUSIONS

Intact hemostasis at the time of hemarthrosis and during healing are both critical to prevent vascular remodeling, which appears worse with severe and prolonged FVIII deficiency. Unbiased RNA sequencing revealed potential targets for intervention and biomarker development to improve management of HA.

Revascularization after angiogenesis inhibition favors new sprouting over abandoned vessel reuse

Inhibiting pathologic angiogenesis can halt disease progression, but such inhibition may offer only a temporary benefit, followed by tissue revascularization after treatment stoppage. This revascularization, however, occurs by largely unknown phenotypic changes in pathologic vessels. To investigate the dynamics of vessel reconfiguration during revascularization, we developed a model of reversible murine corneal angiogenesis permitting longitudinal examination of the same vasculature. Following 30 days of angiogenesis inhibition, two types of vascular structure were evident: partially regressed persistent vessels that were degenerate and barely functional, and fully regressed, non-functional empty basement membrane sleeves (ebms). While persistent vessels maintained a limited flow and retained collagen IV+ basement membrane, CD31+ endothelial cells (EC), and α-SMA+ pericytes, ebms were acellular and expressed only collagen IV. Upon terminating angiogenesis inhibition, transmission electron microscopy and live imaging revealed that revascularization ensued by a rapid reversal of EC degeneracy in persistent vessels, facilitating their phenotypic normalization, vasodilation, increased flow, and subsequent new angiogenic sprouting. Conversely, ebms were irreversibly sealed from the circulation by excess collagen IV deposition that inhibited EC migration and prevented their reuse. Fully and partially regressed vessels therefore have opposing roles during revascularization, where fully regressed vessels inhibit new sprouting while partially regressed persistent vessels rapidly reactivate and serve as the source of continued pathologic angiogenesis.

Matrix metalloproteinase signals following neurotrauma are right on cue

Neurotrauma, a term referencing both traumatic brain and spinal cord injuries, is unique to neurodegeneration in that onset is clearly defined. From the perspective of matrix metalloproteinases (MMPs), there is opportunity to define their temporal participation in injury and recovery beginning at the level of the synapse. Here we examine the diverse roles of MMPs in the context of targeted insults (optic nerve lesion and hippocampal and olfactory bulb deafferentation), and clinically relevant focal models of traumatic brain and spinal cord injuries. Time-specific MMP postinjury signaling is critical to synaptic recovery after focal axonal injuries; members of the MMP family exhibit a signature temporal profile corresponding to axonal degeneration and regrowth, where they direct postinjury reorganization and synaptic stabilization. In both traumatic brain and spinal cord injuries, MMPs mediate early secondary pathogenesis including disruption of the blood-brain barrier, creating an environment that may be hostile to recovery. They are also critical players in wound healing including angiogenesis and the formation of an inhibitory glial scar. Experimental strategies to reduce their activity in the acute phase result in long-term neurological recovery after neurotrauma and have led to the first clinical trial in spinal cord injured pet dogs.

Targeting Angiogenesis in Prostate Cancer

Prostate cancer is the most commonly diagnosed cancer among men in the Western world. Although localized disease can be effectively treated with established surgical and radiopharmaceutical treatments options, the prognosis of castration-resistant advanced prostate cancer is still disappointing. The objective of this study was to review the role of angiogenesis in prostate cancer and to investigate the effectiveness of anti-angiogenic therapies. A literature search of clinical trials testing the efficacy of anti-angiogenic therapy in prostate cancer was performed using Pubmed. Surrogate markers of angiogenic activity (microvessel density and vascular endothelial growth factor A (VEGF-A) expression) were found to be associated with tumor grade, metastasis, and prognosis. Six randomizedstudies were included in this review: two phase II trials on localized and hormone-sensitive disease (n = 60 and 99 patients) and four phase III trials on castration-resistant refractory disease (n = 873 to 1224 patients). Although the phase II trials showed improved relapse-free survival and stabilisation of the disease, the phase III trials found increased toxicity and no significant improvement in overall survival. Although angiogenesis appears to have an important role in prostate cancer, the results of anti-angiogenic therapy in castration-resistant refractory disease have hitherto been disappointing. There are various possible explanations for this lack of efficacy in castration-resistant refractory disease: redundancy of angiogenic pathways, molecular heterogeneity of the disease, loss of tumor suppressor protein phosphatase and tensin homolog (PTEN) expression as well as various VEGF-A splicing isoforms with pro- and anti-angiogenic activity. A better understanding of the molecular mechanisms of angiogenesis may help to develop effective anti-angiogenic therapy in prostate cancer.

A current perspective of canstatin, a fragment of type IV collagen alpha 2 chain

Type IV collagen is a main component of basement membrane extracellular matrix. Canstatin, a non-collagenous C-terminal fragment of type IV collagen α2 chain, was firstly identified as an endogenous anti-angiogenic and anti-tumor factor, which also has an anti-lymphangiogenic effect. Then, canstatin has been widely investigated as a novel target molecule for cancer therapy. The anti-angiogenic effect of canstatin may be also useful for the treatment of ocular neovascularization. Recently, we have demonstrated that canstatin, which is abundantly expressed in the heart tissue, exerts various biological activities in cardiac cells. In rat H9c2 cardiomyoblasts, canstatin inhibits isoproterenol- or hypoxia-induced apoptosis. Canstatin plays an important role in modulating voltage-dependent calcium channel activity in rat cardiomyocytes. Canstatin also regulates various biological functions in rat cardiac fibroblasts and myofibroblasts. The expression of canstatin decreases in the infarcted area after myocardial infarction. This review focuses on a current perspective for the roles of canstatin in tumorigenesis, ocular neovascularization and cardiac pathology.

Targeting corneal inflammation by gene therapy: Emerging strategies for keratitis

Inflammation is the underlying process of several diseases within the eye, specifically in the cornea. Current treatment options for corneal inflammation or keratitis, and related neovascularization, are restricted by limited efficacy, adverse effects, and short duration of action. Gene therapy has shown great potential for the treatment of diseases affecting the ocular surface, and major efforts are being targeted to inflammatory mediators and neovascularization, in order to develop potential treatments for corneal inflammation. Gene therapy to treat ocular disorders is still starting, and current therapies are primarily experimental, with most human clinical trials still in research state, although some of them have already shown encouraging results. In this review, we focus on the progress and challenges of gene therapy to treat corneal inflammation. After introducing the inflammation process, we present the main nucleic acid delivery systems, including viral and non-viral vectors, and the most studied strategies to address the therapy: control of neovascularization and regulation of pro- and anti-inflammatory cytokines.

Canstatin inhibits isoproterenol-induced apoptosis through preserving mitochondrial morphology in differentiated H9c2 cardiomyoblasts

Canstatin, a non-collagenous fragment, is cleaved from type IV collagen α2 chain, an essential component of basement membrane surrounding cardiomyocytes. Although canstatin is known as an endogenous anti-angiogenic factor, its effects on cardiomyocytes have not been clarified. This study examined the effects of canstatin on isoproterenol-induced apoptosis in differentiated H9c2 cardiomyoblasts. Retinoic acid was used to differentiate H9c2 myoblast to cardiomyocyte-like phenotype. Cell viability was determined by a cell counting assay. Western blotting was performed to detect expression of cleaved casepase-3 and phosphorylation of dynamin related protein (Drp)1 at Ser637 which regulates mitochondrial fission. Mito Sox Red staining was performed to examine a mitochondria-dependent production of reactive oxygen species (ROS). Mitochondrial morphology was detected by Mito Tracker Red staining. Isoproterenol (100 μM, 48 h) significantly decreased cell viability and increased cleaved caspase-3 expression, which were inhibited by canstatin (10-250 ng/ml) in a concentration-dependent manner. Canstatin suppressed the isoproterenol-induced mitochondrial fission but not ROS. Canstatin also inhibited the isoproterenol-induced dephosphorylation of Drp1 at Ser637. In conclusion, canstatin inhibits isoproterenol-induced apoptosis through the inhibition of mitochondrial fission via the suppression of dephosphorylation of Drp1 at Ser637 in differentiated H9c2 cardiomyoblasts.

The good and the bad collagens of fibrosis - Their role in signaling and organ function

Usually the dense extracellular structure in fibrotic tissues is described as extracellular matrix (ECM) or simply as collagen. However, fibrosis is not just fibrosis, which is already exemplified by the variant morphological characteristics of fibrosis due to viral versus cholestatic, autoimmune or toxic liver injury, with reticular, chicken wire and bridging fibrosis. Importantly, the overall composition of the ECM, especially the relative amounts of the many types of collagens, which represent the most abundant ECM molecules and which centrally modulate cellular functions and physiological processes, changes dramatically during fibrosis progression. We hypothesize that there are good and bad collagens in fibrosis and that a change of location alone may change the function from good to bad. Whereas basement membrane collagen type IV anchors epithelial and other cells in a polarized manner, the interstitial fibroblast collagens type I and III do not provide directional information. In addition, feedback loops from biologically active degradation products of some collagens are examples of the importance of having the right collagen at the right place and at the right time controlling cell function, proliferation, matrix production and fate. Examples are the interstitial collagen type VI and basement membrane collagen type XVIII. Their carboxyterminal propeptides serve as an adipose tissue hormone, endotrophin, and as a regulator of angiogenesis, endostatin, respectively. We provide an overview of the 28 known collagen types and propose that the molecular composition of the ECM in fibrosis needs careful attention to assess its impact on organ function and its potential to progress or reverse. Consequently, to adequately assess fibrosis and to design optimal antifibrotic therapies, we need to dissect the molecular entity of fibrosis for the molecular composition and spatial distribution of collagens and the associated ECM.

Basic Components of Vascular Connective Tissue and Extracellular Matrix

Though the composition of the three layers constituting the blood vessel wall varies among the different types of blood vessels, and some layers may even be missing in capillaries, certain basic components, and properties are shared by all blood vessels, though each histologically distinct layer contains a unique complement of extracellular components, growth factors and cytokines, and cell types as well. The structure and composition of vessel layers informs and is informed by the function of the particular blood vessel. The adaptation of the composition and the resulting function of the extracellular matrix (ECM) to changes in circulation/blood flow and a variety of other extravascular stimuli can be characterized as remodeling spearheaded by vascular cells. There is a surprising amount of cell traffic among the three layers. It starts with endothelial cell mediated transmigration of inflammatory cells from the bloodstream into the subendothelium, and then into tissue adjoining the blood vessel. Smooth muscle cells and a variety of adventitial cells reside in tunica media and tunica externa, respectively. The latter cells are a mixture of progenitor/stem cells, fibroblasts, myofibroblasts, pericytes, macrophages, and dendritic cells and respond to endothelial injury by transdifferentiation as they travel into the two inner layers, intima and media for corrective mission in the ECM composition. This chapter addresses the role of various vascular cell types and ECM components synthesized by them in maintenance of normal structure and in their contribution to major pathological processes, such as atherosclerosis, organ fibrosis, and diabetic retinopathy.

The vascular basement membrane in the healthy and pathological brain

The vascular basement membrane contributes to the integrity of the blood-brain barrier (BBB), which is formed by brain capillary endothelial cells (BCECs). The BCECs receive support from pericytes embedded in the vascular basement membrane and from astrocyte endfeet. The vascular basement membrane forms a three-dimensional protein network predominantly composed of laminin, collagen IV, nidogen, and heparan sulfate proteoglycans that mutually support interactions between BCECs, pericytes, and astrocytes. Major changes in the molecular composition of the vascular basement membrane are observed in acute and chronic neuropathological settings. In the present review, we cover the significance of the vascular basement membrane in the healthy and pathological brain. In stroke, loss of BBB integrity is accompanied by upregulation of proteolytic enzymes and degradation of vascular basement membrane proteins. There is yet no causal relationship between expression or activity of matrix proteases and the degradation of vascular matrix proteins in vivo. In Alzheimer's disease, changes in the vascular basement membrane include accumulation of Aβ, composite changes, and thickening. The physical properties of the vascular basement membrane carry the potential of obstructing drug delivery to the brain, e.g. thickening of the basement membrane can affect drug delivery to the brain, especially the delivery of nanoparticles.