The inhibitory effects of endostatin on endothelial cells are modulated by extracellular matrix

Update on the Epidemiology, Pathogenesis, and Biomarkers of Cerebral Autosomal Dominant Arteriopathy With Subcortical Infarcts and Leukoencephalopathy

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is the most common monogenic disorder of the cerebral small blood vessels. It is caused by mutations in the NOTCH3 gene on chromosome 19, and more than 280 distinct pathogenic mutations have been reported to date. CADASIL was once considered a very rare disease with an estimated prevalence of 1.3-4.1 per 100,000 adults. However, recent large-scale genomic studies have revealed a high prevalence of pathogenic NOTCH3 variants among the general population, with the highest risk being among Asians. The disease severity and age at onset vary significantly even among individuals who carry the same NOTCH3 mutations. It is still unclear whether a significant genotype-phenotype correlation is present in CADASIL. The accumulation of granular osmiophilic material in the vasculature is a characteristic feature of CADASIL. However, the exact pathogenesis of CADASIL remains largely unclear despite various laboratory and clinical observations being made. Major hypotheses proposed so far have included aberrant NOTCH3 signaling, toxic aggregation, and abnormal matrisomes. Several characteristic features have been observed in the brain magnetic resonance images of patients with CADASIL, including subcortical lacunar lesions and white matter hyperintensities in the anterior temporal lobe or external capsule, which were useful in differentiating CADASIL from sporadic stroke in patients. The number of lacunes and the degree of brain atrophy were useful in predicting the clinical outcomes of patients with CADASIL. Several promising blood biomarkers have also recently been discovered for CADASIL, which require further research for validation.

Recent Developments in Extracellular Matrix Remodeling for Fat Grafting

Remodeling of the extracellular matrix (ECM), which provides structural and biochemical support for surrounding cells, is vital for adipose tissue regeneration after autologous fat grafting. Rapid and high-quality ECM remodeling can improve the retention rate after fat grafting by promoting neovascularization, regulating stem cells differentiation, and suppressing chronic inflammation. The degradation and deposition of ECM are regulated by various factors, including hypoxia, blood supply, inflammation, and stem cells. By contrast, ECM remodeling alters these regulatory factors, resulting in a dynamic relationship between them. Although researchers have attempted to identify the cellular sources of factors associated with tissue regeneration and regulation of the microenvironment, the factors and mechanisms that affect adipose tissue ECM remodeling remain incompletely understood. This review describes the process of adipose ECM remodeling after grafting and summarizes the factors that affect ECM reconstruction. Also, this review provides an overview of the clinical methods to avoid poor ECM remodeling. These findings may provide new ideas for improving the retention of adipose tissue after fat transplantation.

A functional outside-in signaling network of proteoglycans and matrix molecules regulating autophagy

Proteoglycans and selected extracellular matrix constituents are emerging as intrinsic and critical regulators of evolutionarily conversed, intracellular catabolic pathways. Often, these secreted molecules evoke sustained autophagy in a variety of cell types, tissues, and model systems. The unique properties of proteoglycans have ushered in a paradigmatic shift to broaden our understanding of matrix-mediated signaling cascades. The dynamic cellular pathway controlling autophagy is now linked to an equally dynamic and fluid signaling network embedded in a complex meshwork of matrix molecules. A rapidly emerging field of research encompasses multiple matrix-derived candidates, representing a menagerie of soluble matrix constituents including decorin, biglycan, endorepellin, endostatin, collagen VI and plasminogen kringle 5. These matrix constituents are pro-autophagic and simultaneously anti-angiogenic. In contrast, perlecan, laminin α2 chain, and lumican have anti-autophagic functions. Mechanistically, each matrix constituent linked to intracellular catabolic events engages a specific cell surface receptor that often converges on a common core of the autophagic machinery including AMPK, Peg3 and Beclin 1. We consider this matrix-evoked autophagy as non-canonical given that it occurs in an allosteric manner and is independent of nutrient availability or prevailing bioenergetics control. We propose that matrix-regulated autophagy is an important outside-in signaling mechanism for proper tissue homeostasis that could be therapeutically leveraged to combat a variety of diseases.

Harnessing the Secretome of Mesenchymal Stromal Cells for Traumatic Spinal Cord Injury: Multicell Comparison and Assessment of In Vivo Efficacy

Cell therapy offers significant promise for traumatic spinal cord injury (SCI), which despite many medical advances, has limited treatment strategies. Able to address the multifactorial and dynamic pathophysiology of SCI, cells present various advantages over standard pharmacological approaches. However, the use of live cells is also severely hampered by logistical and practical considerations. These include specialized equipment and expertise, standardization of cell stocks, sustained cell viability post-thawing, and cryopreservation-induced delayed-onset cell death. For this reason, we suggest a novel and clinically translatable alternative to live-cell systemic infusion, which retains the efficacy of the latter while overcoming many of its limitations. This strategy involves the administration of concentrated cell secretome and exploits the trophic mechanism by which stromal cells function. In this study, we compare the efficacy of intravenously delivered concentrated conditioned media (CM) from human umbilical cord matrix cells (HUCMCs), bone marrow mesenchymal stromal cells, as well as newborn and adult fibroblasts in a rat model of moderately severe cervical clip compression/contusion injury (C7--T1, 35 g). This is further paired with a thorough profile of the CM cytokines, chemokines, and angiogenic factors. The HUCMC-derived CM was most effective at limiting acute (48 h post-SCI) vascular pathology, specifically lesion volume, and functional vascularity. Principle component analysis (PCA), hierarchical clustering, and interaction analysis of proteins highly expressed in the HUCMC secretome suggest involvement of the MAPK/ERK, JAK/STAT, and immune cell migratory pathways. This "secretotherapeutic" strategy represents a novel and minimally invasive method to target multiple organ systems and several pathologies shortly after traumatic SCI.

Inhibitory Effect of Topical Cartilage Acellular Matrix Suspension Treatment on Neovascularization in a Rabbit Corneal Model

BACKGROUND

The extracellular matrix (ECM) of articular cartilage has an inhibitory effect on vascularization, yet clinical utilization has been technically challenging. In this study, we aimed to fabricate a biologically functional ECM powder suspension from porcine articular cartilage that inhibits neovascularization (NV).

METHODS

The digested-cartilage acellular matrix (dg-CAM) was prepared by sequential processes of decellularization, enzymatic digestion and pulverization. Physicochemical properties of dg-CAM were compared with that of native cartilage tissue (NCT). Cellular interactions between human umbilical vein endothelial cells (HUVECs) and dg-CAM was evaluated with proliferation, migration and tube formation assays compared with that of type I collagen (COL) and bevacizumab, an anti-angiogenic drug. We then investigated the therapeutic potential of topical administration of dg-CAM suspension on the experimentally induced rabbit corneal NV model.

RESULTS

The dg-CAM released a significantly larger amount of soluble proteins than that of the NCT and showed an improved hydrophilic and dispersion properties. In contrast, the dg-CAM contained a large amount of collagen, glycosaminoglycans and anti-angiogenic molecules as much as the NCT. The inhibitory effect on NV of the dg-CAM was more prominent than that of COL and even comparable to that of bevacizumab in inhibiting the HUVECs. The therapeutic potential of the dg-CAM was comparable to that of bevacizumab in the rabbit corneal NV model by efficiently inhibiting neovessel formation of the injured cornea.

CONCLUSION

The current study developed a dg-CAM having anti-angiogenic properties, together with water-dispersible properties suitable for topical or minimally invasive application for prevention of vessel invasion.

Effects of amelogenins on angiogenesis-associated processes of endothelial cells

OBJECTIVE

To study the effects of an amelogenin mixture on integrin-dependent adhesion, DNA synthesis and apoptosis of cultured human dermal microvascular endothelial cells and angiogenesis in an organotypic assay.

METHOD

Immobilised antibodies against specific integrins (alpha-1, alpha-2, alpha-3, alpha-4, alpha-5, alpha-v, ß1, ß2, ß3, ß4, ß6, alpha-vß3, alpha-vß5 and alpha-5ß1) were used to capture treated human dermal microvascular endothelial cells, which were detected colourimetrically. DNA synthesis of the cells was monitored by 5-bromo-2'- deoxyuridine incorporation and apoptosis by a TdT-mediated dUTP nick-end labelling technique. Tubule formation from aortic arches of 13-d-old chick embryos were followed over 48h.

RESULTS

The amelogenin mixture increased microvessel outgrowth by 76% (p < 0.01, n=12) from the aortic explants. Also, amelogenins increased the adhesion (p < 0.01, n = 5) by multiple angiogenesis associated integrin subunits and alpha-vß3, alpha-vß5 and alpha-5ß1 heterodimers on human dermal microvascular endothelial cells at a non-mitogenic concentration (100 µg/ml). Conversely, amelogenins at 1,000 µg/ml decreased microvessel formation possibly due to attenuation of corresponding integrins despite increasing (p < 0.001, n = 8) DNA synthesis. No significant apoptosis was detected in human dermal microvascular endothelial cells cultured on Matrigel with and without amelogenins.

CONCLUSION

Increased surface expression of integrins on endothelial cells may contribute to the proangiogenic property of amelogenins.

Serum endostatin is a genetically determined predictor of survival in pulmonary arterial hypertension

RATIONALE

Pulmonary arterial hypertension (PAH) is a medically incurable disease resulting in death from right ventricular (RV) failure. Both pulmonary vascular and RV remodeling are linked to dynamic changes in the microvasculature. Therefore, we hypothesized that circulating angiostatic factors could be linked to outcomes and represent novel biomarkers of disease severity in PAH.

OBJECTIVES

We sought to determine the relationship of a potent angiostatic factor, endostatin (ES), with disease severity and mortality in PAH. Furthermore, we assessed genetic predictors of ES expression and/or function and their association with outcomes in PAH.

METHODS

We measured levels of serum ES in two independent cohorts of patients with PAH. Contemporaneous clinical data included New York Heart Association functional class, 6-minute-walk distance, invasive hemodynamics, and laboratory chemistries.

MEASUREMENTS AND MAIN RESULTS

Serum ES correlated with poor functional status, decreased exercise tolerance, and invasive hemodynamics variables. Furthermore, serum ES was a strong predictor of mortality. A loss-of-function, missense variant in the gene encoding ES, Col18a1, was linked to lower circulating protein and was independently associated with reduced mortality.

CONCLUSIONS

Our data link increased expression of ES to disease severity in PAH and demonstrate a significant relationship with adverse outcomes. Circulating ES levels can be genetically influenced, implicating ES as a genetically determined modifier of disease severity impacting on survival. These observations support serum ES as a potential biomarker in PAH with the capacity to predict poor outcomes. More importantly, this study implicates Col18a1/ES as a potential new therapeutic target in PAH.

Serum endostatin levels are elevated in colorectal cancer and correlate with invasion and systemic inflammatory markers

Background:

Endostatin, a fragment of collagen XVIII, is an endogenous angiogenesis inhibitor with anti-tumour functions. However, elevated circulating endostatin concentrations have been found in several human cancers including colorectal cancer (CRC).

Methods:

Serum endostatin levels were measured by enzyme-linked immunoassay from a series of 143 patients with CRC and from 84 controls, and correlated with detailed clinicopathological features of CRC, serum leukocyte differential count and C-reactive protein (CRP) levels.

Results:

Patients with CRC had higher serum endostatin levels than the controls (P=0.005), and high levels associated with age, tumour invasion through the muscularis propria and poor differentiation, but not with metastases. Endostatin levels showed a positive correlation with the markers of systemic inflammatory response and a negative correlation with the densities of tumour-infiltrating mast cells and dendritic cells. Collagen XVIII was expressed in tumour stroma most strikingly in blood vessels and capillaries, and in the muscle layer of the bowel wall.

Conclusions:

Elevated endostatin levels in CRC correlate with systemic inflammation and invasion through the muscularis propria. Increased endostatin level may be a result of invasion-related cleavage of collagen XVIII expressed in the bowel wall. The negative correlations between serum endostatin and intratumoural mast cells and immature dendritic cells may reflect angiogenesis inhibition by endostatin.

Inhibition of blood vessel formation by a chondrocyte-derived extracellular matrix

In this study, the chondrocyte-derived extracellular matrix (CECM) was evaluated for its activity to inhibit vessel invasion in vitro and in vivo. Human umbilical vein endothelial cells (HUVECs) and rabbit chondrocytes were plated on a bio-membrane made of CECM or human amniotic membrane (HAM). The adhesion, proliferation, and tube formation activity of HUVECs and chondrocytes were examined. The CECM and HAM powders were then mixed individually in Matrigel and injected subcutaneously into nude mice to examine vessel invasion in vivo after 1 week. Finally, a rabbit model of corneal neovascularization (NV) was induced by 3-point sutures in the upper cornea, and CECM and HAM membranes were implanted onto the corneal surface at day 5 after suture injury. The rabbits were sacrificed at 7 days after transplantation and the histopathological analysis was performed. The adhesion and proliferation of HUVECs were more efficient on the HAM than on the CECM membrane. However, chondrocytes on each membrane showed an opposite result being more efficient on the CECM membrane. The vessel invasion in vivo also occurred more deeply and intensively in Matrigel containing HAM than in the one containing CECM. In the rabbit NV model, CECM efficiently inhibited the neovessels formation and histological remodeling in the injured cornea. In summary, our findings suggest that CECM, an integral cartilage ECM composite, shows an inhibitory effect on vessel invasion both in vitro and in vivo, and could be a useful tool in a variety of biological and therapeutic applications including the prevention of neovascularization after cornea injury.

Focal adhesion kinase inhibitors are potent anti-angiogenic agents

Focal adhesion kinase (FAK), a cytoplasmic tyrosine kinase and scaffold protein localized to focal adhesions, is uniquely positioned at the convergence point of integrin and receptor tyrosine kinase signal transduction pathways. FAK is overexpressed in many tumor cells, hence various inhibitors targeting its activity have been tested for anti-tumor activity. However, the direct effects of these pharmacologic agents on the endothelial cells of the vasculature have not been examined. Using primary human umbilical vein endothelial cells (HUVEC), we characterized the effects of two FAK inhibitors, PF-573,228 and FAK Inhibitor 14 on essential processes for angiogenesis, such as migration, proliferation, viability and endothelial cell tube formation. We observed that treatment with either FAK Inhibitor 14 or PF-573,228 resulted in reduced HUVEC viability, migration and tube formation in response to vascular endothelial growth factor (VEGF). Furthermore, we found that PF-573,228 had the added ability to induce apoptosis of endothelial cells within 36 h post-drug administration even in the continued presence of VEGF stimulation. FAK inhibitors also resulted in modification of the actin cytoskeleton within HUVEC, with observed increased stress fiber formation in the presence of drug. Given that endothelial cells were sensitive to FAK inhibitors at concentrations well below those reported to inhibit tumor cell migration, we confirmed their ability to inhibit endothelial-derived FAK autophosphorylation and FAK-mediated phosphorylation of recombinant paxillin at these doses. Taken together, our data indicate that small molecule inhibitors of FAK are potent anti-angiogenic agents and suggest their utility in combinatorial therapeutic approaches targeting tumor angiogenesis.

A novel fragment derived from the beta chain of human fibrinogen, beta43-63, is a potent inhibitor of activated endothelial cells in vitro and in vivo

BACKGROUND

Angiogenesis and haemostasis are closely linked within tumours with many haemostatic proteins regulating tumour angiogenesis. Indeed we previously identified a fragment of human fibrinogen, fibrinogen E-fragment (FgnE) with potent anti-angiogenic properties in vitro and cytotoxic effects on tumour vessels in vivo. We therefore investigated which region of FgnE was mediating vessel cytotoxicity.

METHODS

Human dermal microvascular endothelial cells (ECs) were used to test the efficacy of peptides derived from FgnE on proliferation, migration, differentiation, apoptosis and adhesion before testing the efficacy of an active peptide on tumour vasculature in vivo.

RESULTS

We identified a 20-amino-acid peptide derived from the beta chain of FgnE, beta43-63, which had no effect on EC proliferation or migration but markedly inhibited the ability of activated ECs to form tubules or to adhere to various constituents of the extracellular matrix - collagen IV, fibronectin and vitronectin. Furthermore, our data show that beta43-63 interacts with ECs, in part, by binding to alpha(v)beta(3), so soluble alpha(v)beta(3) abrogated beta43-63 inhibition of tubule formation by activated ECs. Finally, when injected into mice bearing tumour xenografts, beta43-63 inhibited tumour vascularisation and induced formation of significant tumour necrosis.

CONCLUSIONS

Taken together, these data suggest that beta43-63 is a novel anti-tumour peptide whose anti-angiogenic effects are mediated by alpha(v)beta(3).

Angiogenic effect of naive and 5-fluorouracil resistant colon carcinoma on endothelial cells in vitro

Tumour associated neovascularisation is a complex interplay between inhibitory and stimulatory angiogenic factors. Despite intense research in this field, little is known about the interaction between endothelial and chemoresistant cancer cells. For this purpose, we assessed the impact of cellular supernatants of the primary adenocarcinoma cell line CCL228, its lymph node metastasis CCL227, and four subclones resistant to different levels of 5-fluorouracil on the growth of microvascular and macrovascular endothelial cells. The growth of endothelial cells in vitro was affected to a moderate degree by supernatants from colon cancer cell lines. This effect was independent of the degree of chemoresistance. The stimulation of endothelial cells by the growth factors VEGF, bFGF, and PD-ECGF in the presence of supernatants from cancer cell lines was generally higher in macrovascular endothelial cells when compared with microvascular cells. The secretion of VEGF from colon cancer cells in vitro was inversely related to the degree of chemoresistance with the low chemoresistance phenotype producing VEGF 8.7-fold higher than the high resistance subclone. With a maximal secretion of 1500 pg VEGF/ml cell supernatant, the concentration necessary to directly stimulate the growth of endothelial cells was not achieved. In conclusion, chemoresistance affects the interaction between colon cancer cells and endothelial cells dependant on the endothelial cell type. Although the level of chemoresistance has a profound impact on the production of VEGF by cancer cells with low, intermediate or high resistance, it does not differentially affect growth stimulation or inhibition of endothelial cells in vitro.

Polymers for pro- and anti-angiogenic therapy

Dysregulated growth factor signaling is traditionally targeted via bolus injections of therapeutic molecules, but this approach may not recreate necessary qualitative and quantitative aspects of biologic growth factor delivery systems. Polymeric delivery systems may, instead, mimic certain sequestration and binding characteristics of the extracellular matrix and lead to the provision of therapeutic molecules at therapeutically efficient local concentrations [V], in the form of spatial gradients (d[V]/dx) and temporal gradients (d[V]/dt), and in combination with other morphogenetic cues. Both physicochemical and biological attributes dictate their design, and they may be fabricated from synthetic and natural polymers. General concepts for manipulating growth factor signaling with these systems are discussed in the context of angiogenesis with vascular endothelial growth factor (VEGF), and these strategies may be broadly adapted to a multitude of other morphogens and growth factors.

Tumor Anti-angiogenic Gene Therapy with Microencapsulated Recombinant CHO Cells

Microencapsulation of recombinant cells is a novel promising approach to tumor therapy in which therapeutic protein is sustainable and long-term delivered by microencapsulated cells. The semi-permeable membrane of microcapsule can protect cell from host's immune rejection, increase the chemical stability of therapeutic protein and circumvent the problems of toxicity, limited half-lives and variation in circulating levels. Endostatin, a potent and specific angiogenesis inhibitor, could suppress the growth of primary and metastatic lesions in multiple murine tumor models. In this paper, APA microcapsules with high strength kept intact over 35 days and recombinant CHO cells kept the rapid proliferation viability and the continuous endostatin-expression function. The study of tumor treatment showed that the implantation of microencapsulated recombinant CHO cells decreased the neovascularization of tumor tissue by 59.4% and inhibited the B16 melanoma growth by 77.4%. Twenty days after tumor cell injection, 80% of animals treated with microencapsulated CHO-endo cells were alive compared to only 50% of animals in either control or mock control groups. Therefore, continuous delivery of endostatin from microencapsulated recombinant cells represents a feasible approach to tumor therapy.