Hyaluronic acid alters vessel behavior in CXCL12-treated HUVECs

Hyaluronic acid (HA) is a key component of the extracellular matrix known for absorbing water, swelling, and altering solid stress of tumors. HA’s anionic behavior may provide important biochemical effects toward tumor progression as well. Tumors obtain nutrients by relying on signaling molecules such as CXCL12 to recruit blood vessels and promote vessel leakage. Recent work suggests that additional positively-charged residues on CXCL12’s β and γ isoforms cause different biochemical functionality compared to the well-studied α isoform. These studies aimed to determine whether the presence of HA in a tumor’s microenvironment could alter the relative response strength of CXCL12’s various isoforms on blood vessel sprouting and apparent vascular permeability. The vessel microenvironment was modeled using a 3-channel microfluidic device with Human Umbilical Vein Endothelial Cells (HUVECs) in the outer channels forming monolayers against a 3D collagen or collagen/HA matrix in the center channel. HUVECs were cultured with media containing recombinant CXCL12 (α, β or γ). Results show that total HUVEC sprouting area follows an α>β>γ trend in isoform-treated HUVECs within a collagen matrix, matching the binding affinity order of CXCL12 to endothelial CXCR4 receptors. The presence of HA decreased overall sprouting response but shifted pro-angiogenic potency towards CXCL12’s γ isoform. Vascular permeability studies also showed an α>β>γ trend for HUVECs in collagen. With HA added, control and α-treated HUVECs became less permeable while γ-treated HUVECs became more permeable. Overall results suggest that an HA-infused collagen matrix facilitates γ isoform binding, leading to a stronger isoform-specific vessel response. Knowing how HA impacts CXCL12 isoform potency on vessels will help in the future design of CXCL12-targeted cancer therapies.The American Heart AssociationInstitute for Materials Research at OSULumley Engineering FundPelotoniaA one-year embargo was granted for this item.Academic Major: Chemical Engineerin

Positive and negative regulation of angiogenesis by soluble vascular endothelial growth factor receptor-1

Vascular endothelial growth factor receptor (VEGFR)-1 exists in different forms, derived from alternative splicing of the same gene. In addition to the transmembrane form, endothelial cells produce a soluble VEGFR-1 (sVEGFR-1) isoform, whereas non-endothelial cells produce both sVEGFR-1 and a different soluble molecule, known as soluble fms-like tyrosine kinase (sFlt)1-14. By binding members of the vascular endothelial growth factor (VEGF) family, the soluble forms reduce the amounts of VEGFs available for the interaction with their transmembrane receptors, thereby negatively regulating VEGFR-mediated signaling. In agreement with this activity, high levels of circulating sVEGFR-1 or sFlt1-14 are associated with different pathological conditions involving vascular dysfunction. Moreover, sVEGFR-1 and sFlt1-14 have an additional role in angiogenesis: they are deposited in the endothelial cell and pericyte extracellular matrix, and interact with cell membrane components. Interaction of sVEGFR-1 with α5β1 integrin on endothelial cell membranes regulates vessel growth, triggering a dynamic, pro-angiogenic phenotype. Interaction of sVEGFR-1/sFlt1-14 with cell membrane glycosphingolipids in lipid rafts controls kidney cell morphology and glomerular barrier functions. These cell-matrix contacts represent attractive novel targets for pharmacological intervention in addition to those addressing interactions between VEGFs and their receptors

Tumor angiogenesis and anti-angiogenic therapy in malignant gliomas revisited

The cellular and molecular mechanisms of tumor angiogenesis and its prospects for anti-angiogenic cancer therapy are major issues in almost all current concepts of both cancer biology and targeted cancer therapy. Currently, (1) sprouting angiogenesis, (2) vascular co-option, (3) vascular intussusception, (4) vasculogenic mimicry, (5) bone marrow-derived vasculogenesis, (6) cancer stem-like cell-derived vasculogenesis and (7) myeloid cell-driven angiogenesis are all considered to contribute to tumor angiogenesis. Many of these processes have been described in developmental angiogenesis; however, the relative contribution and relevance of these in human brain cancer remain unclear. Preclinical tumor models support a role for sprouting angiogenesis, vascular co-option and myeloid cell-derived angiogenesis in glioma vascularization, whereas a role for the other four mechanisms remains controversial and rather enigmatic. The anti-angiogenesis drug Avastin (Bevacizumab), which targets VEGF, has become one of the most popular cancer drugs in the world. Anti-angiogenic therapy may lead to vascular normalization and as such facilitate conventional cytotoxic chemotherapy. However, preclinical and clinical studies suggest that anti-VEGF therapy using bevacizumab may also lead to a pro-migratory phenotype in therapy resistant glioblastomas and thus actively promote tumor invasion and recurrent tumor growth. This review focusses on (1) mechanisms of tumor angiogenesis in human malignant glioma that are of particular relevance for targeted therapy and (2) controversial issues in tumor angiogenesis such as cancer stem-like cell-derived vasculogenesis and bone-marrow-derived vasculogenesis

Computational Modeling to Quantify the Contributions of VEGFR1, VEGFR2, and Lateral Inhibition in Sprouting Angiogenesis

Sprouting angiogenesis is a necessary process in regeneration and development as well as in tumorigenesis. VEGF-A is the main pro-angiogenic chemoattractant and it can bind to the decoy receptor VEGFR1 or to VEGFR2 to induce sprouting. Active sprout cells express Dll4, which binds to Notch1 on neighboring cells, in turn inhibiting VEGFR2 expression. It is known that the balance between VEGFR2 and VEGFR1 determines tip selection and network architecture, however the quantitative interrelationship of the receptors and their interrelated balances, also with relation to Dll4-Notch1 signaling, remains yet largely unknown. Here, we present an agent-based computer model of sprouting angiogenesis, integrating VEGFR1 and VEGFR2 in a detailed model of cellular signaling. Our model reproduces experimental data on VEGFR1 knockout. We show that soluble VEGFR1 improves the efficiency of angiogenesis by directing sprouts away from existing cells over a wide range of parameters. Our analysis unravels the relevance of the stability of the active notch intracellular domain as a dominating hub in this regulatory network. Our analysis quantitatively dissects the regulatory interactions in sprouting angiogenesis. Because we use a detailed model of intracellular signaling, the results of our analysis are directly linked to biological entities. We provide our computational model and simulation engine for integration in complementary modeling approaches

Tumour vascularization: sprouting angiogenesis and beyond

Tumour angiogenesis is a fast growing domain in tumour biology. Many growth factors and mechanisms have been unravelled. For almost 30 years, the sprouting of new vessels out of existing ones was considered as an exclusive way of tumour vascularisation. However, over the last years several additional mechanisms have been identified. With the discovery of the contribution of intussusceptive angiogenesis, recruitment of endothelial progenitor cells, vessel co-option, vasculogenic mimicry and lymphangiogenesis to tumour growth, anti-tumour targeting strategies will be more complex than initially thought. This review highlights these processes and intervention as a potential application in cancer therapy. It is concluded that future anti-vascular therapies might be most beneficial when based on multimodal anti-angiogenic, anti-vasculogenic mimicry and anti-lymphangiogenic strategies

VEGFR3: A New Target for Antiangiogenesis Therapy?

VEGFR-3 signaling plays an important role in developmental, physiological, and pathological angiogenesis and lymphangiogenesis. Tammela et al. in Nature show that VEGFR-3, via Notch regulation, is present on endothelial tip cells and is critical to sprouting angiogenesis

Flow dynamics control the effect of sphingosine-1-phosphate on endothelial permeability in a microfluidic vessel bifurcation model

Blood vessels are lined by endothelial cells that form a semipermeable barrier to restrict fluid flow across the vessel wall. The endothelial barrier is known to respond to various molecular mechanisms, but the effects of mechanical signals that arise due to blood flow remain poorly understood. Here, we report a microfluidic model that mimics the flow conditions and endothelial/extracellular matrix (ECM) architecture of a vessel bifurcation to enable systematic investigation of how flow dynamics that arise within bifurcating vessels guides the endothelial response to biochemical signals. Applying the strengths of our system, we further investigate the endothelial response to sphingosine-1-phosphate, a bioactive lipid that has demonstrated flow-dependent regulation of vascular permeability. We demonstrate that bifurcated fluid flow (BFF) that arises at the base of vessel bifurcations and laminar shear stress (LSS) that arises along downstream vessel walls induce a decrease in endothelial permeability. Furthermore, we identify that flow-dynamics and chaperone proteins regulate the endothelial response to S1P. Through pharmacological inhibition of S1P receptors 1 and 2, we report ligand-independent mechanical activation of S1P receptors 1 and 2, providing support for the role of G protein-coupled receptors as mechanosensors. These findings introduce BFF as an important regulator of vascular permeability, and establish flow dynamics as a determinant of the endothelial response to S1P.Pelotonia Fellowship ProgramBarry M. Goldwater Excellence in Education FoundationThe Ohio State University College of EngineeringA one-year embargo was granted for this item.Academic Major: Biomedical Engineerin

Doctor of Philosophy

dissertationAngiogenesis, the formation of new capillaries from pre-existing capillaries or venules, is essential to both health and disease and involved in many tissue-engineering applications. In addition to well-known angiogenic growth factors, mechanical factors, including cyclic stretch, have also been shown to affect angiogenesis, but how cyclic stretch regulates angiogenesis is not yet completely understood. Thus, the purpose of this work was to (1) identify stretch-mediated angiogenic control mechanisms and (2) elucidate how chemical and mechanical angiogenic regulators work in concert. We utilized a stretchable three-dimensional sprouting angiogenesis model, where endothelial cells were seeded on a collagen gel and could invade the gel while concomitantly being exposed to uniaxial cyclic stretch. We discovered that cyclic stretch alone is a strong angiogenic stimulus, and the effects of cyclic stretch on angiogenesis are both stretch magnitude and frequency dependent. We also discovered that cyclic stretch induced angiogenic sprouts to align perpendicular to the direction of stretch. Both the effects of cyclic stretch on the number and alignment of new sprouts were abolished by cytochalasin D (an inhibitor of actin polymerization) or Y27632 (an inhibitor of Rho associated kinase). In contrast, Sunitinib (an inhibitor of receptor tyrosine kinases) abolished cyclic stretch induced sprouting angiogenesis but not associated alignment, suggesting it is possible to separately manipulate the quantity and orientation of new sprouts. We also discovered that the combined effects of stretch and growth factors on angiogenesis varied with growth factors. Stretch and basic fibroblast growth factor (bFGF), but not vascular endothelial growth factor (VEGF), had an additive effect on angiogenesis, and such additive induction was abolished by cytochalasin D. Angiogenesis under the combination of stretch and VEGF was not sensitive to cytochalasin D, but was sensitive to Sunitinib, suggesting a change in molecular controls in the presence of different pro-angiogenic chemical factors. However, actin filaments were vital in stretch-mediated cell alignment, regardless of the presence of additional bFGF or VEGF. Overall, these results provide (1) an in-depth understanding of cyclic stretchmediated angiogenesis and (2) an in vitro experimental model for further experimentation within this research focus, driving toward future angiogenic therapies

Endothelial cells on the move: dynamics in vascular morphogenesis and disease

© 2020 The authors 2020. This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.The vascular system is a hierarchically organized network of blood vessels that play crucial roles in embryogenesis, homeostasis and disease. Blood vessels are built by endothelial cells - the cells lining the interior of blood vessels - through a process named vascular morphogenesis. Endothelial cells react to different biomechanical signals in their environment by adjusting their behavior to: (1) invade, proliferate and fuse to form new vessels (angiogenesis); (2) remodel, regress and establish a hierarchy in the network (patterning); and (3) maintain network stability (quiescence). Each step involves the coordination of endothelial cell differentiation, proliferation, polarity, migration, rearrangements and shape changes to ensure network integrity and an efficient barrier between blood and tissues. In this review, we highlighted the relevance and the mechanisms involving endothelial cell migration during different steps of vascular morphogenesis. We further present evidence on how impaired endothelial cell dynamics can contribute to pathology.C A F was supported by European Research Council Starting Grant (AXIAL.EC; 679368), the Fundação para a Ciência e a Tecnologia funding (grants: IF/00412/2012; EXPL/BEX-BCM/2258/2013; PTDC/MED-PAT/31639/2017; PTDC/BIA-CEL/32180/2017), and a grant from the Fondation Leducq (17CVD03).info:eu-repo/semantics/publishedVersio