751
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Chappell JC, Wiley DM, Bautch VL. Regulation of blood vessel sprouting. Semin Cell Dev Biol 2011; 22:1005-11. [PMID: 22020130 DOI: 10.1016/j.semcdb.2011.10.006] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Revised: 10/03/2011] [Accepted: 10/06/2011] [Indexed: 01/20/2023]
Abstract
Blood vessels are essential conduits of nutrients and oxygen throughout the body. The formation of these vessels involves angiogenic sprouting, a complex process entailing highly integrated cell behaviors and signaling pathways. In this review, we discuss how endothelial cells initiate a vessel sprout through interactions with their environment and with one another, particularly through lateral inhibition. We review the composition of the local environment, which contains an initial set of guidance cues to facilitate the proper outward migration of the sprout as it emerges from a parent vessel. The long-range guidance and sprout stability cues provided by soluble molecules, extracellular matrix components, and interactions with other cell types are also discussed. We also examine emerging evidence for mechanisms that govern sprout fusion with its target and lumen formation.
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Affiliation(s)
- John C Chappell
- Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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752
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Chappell JC, Wiley DM, Bautch VL. How blood vessel networks are made and measured. Cells Tissues Organs 2011; 195:94-107. [PMID: 21996655 DOI: 10.1159/000331398] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Tissue and organ viability depends on the proper systemic distribution of cells, nutrients, and oxygen through blood vessel networks. These networks arise in part via angiogenic sprouting. Vessel sprouting involves the precise coordination of several endothelial cell processes including cell-cell communication, cell migration, and proliferation. In this review, we discuss zebrafish and mammalian models of blood vessel sprouting and the quantification methods used to assess vessel sprouting and network formation in these models. We also review the mechanisms involved in angiogenic sprouting, and we propose that the process consists of distinct stages. Sprout initiation involves endothelial cell interactions with neighboring cells and the environment to establish a specialized tip cell responsible for leading the emerging sprout. Furthermore, local sprout guidance cues that spatially regulate this outward migration are discussed. We also examine subsequent events, such as sprout fusion and lumenization, that lead to maturation of a nascent sprout into a patent blood vessel.
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Affiliation(s)
- John C Chappell
- Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, N.C., USA
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753
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Cariboni A, Davidson K, Dozio E, Memi F, Schwarz Q, Stossi F, Parnavelas JG, Ruhrberg C. VEGF signalling controls GnRH neuron survival via NRP1 independently of KDR and blood vessels. Development 2011; 138:3723-33. [PMID: 21828096 PMCID: PMC3152927 DOI: 10.1242/dev.063362] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Gonadotropin-releasing hormone (GnRH) neurons are neuroendocrine cells that are born in the nasal placode during embryonic development and migrate through the nose and forebrain to the hypothalamus, where they regulate reproduction. Many molecular pathways that guide their migration have been identified, but little is known about the factors that control the survival of the migrating GnRH neurons as they negotiate different environments. We previously reported that the class 3 semaphorin SEMA3A signals through its neuropilin receptors, NRP1 and NRP2, to organise the axons that guide migrating GnRH neurons from their birthplace into the brain. By combining analysis of genetically altered mice with in vitro models, we show here that the alternative neuropilin ligand VEGF164 promotes the survival of migrating GnRH neurons by co-activating the ERK and AKT signalling pathways through NRP1. We also demonstrate that survival signalling relies on neuronal, but not endothelial, NRP1 expression and that it occurs independently of KDR, the main VEGF receptor in blood vessels. Therefore, VEGF164 provides survival signals directly to developing GnRH neurons, independently of its role in blood vessels. Finally, we show that the VEGF164-mediated neuronal survival and SEMA3A-mediated axon guidance cooperate to ensure that migrating GnRH neurons reach the brain. Thus, the loss of both neuropilin ligands leads to an almost complete failure to establish the GnRH neuron system.
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Affiliation(s)
- Anna Cariboni
- Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK
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754
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Lee CY, Bautch VL. Ups and Downs of Guided Vessel Sprouting: The Role of Polarity. Physiology (Bethesda) 2011; 26:326-33. [DOI: 10.1152/physiol.00018.2011] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Blood vessel networks expand to meet oxygen demands via sprouting angiogenesis. This process is heterogeneous but not random; as sprouts form and extend, neighboring endothelial cells do not sprout but divide. Sprouting is regulated by local sprout guidance cues produced by the vessels themselves, as well as extrinsic cues. Endothelial cells in developing vessels orient in several axes to establish migratory polarity, apical-basolateral polarity, and planar cell polarity. Although little is known about how polarity axes are set up or maintained, they are important for vessel formation and function. This review focuses on the current knowledge of how blood vessel sprouting is regulated and guided, the role of endothelial cell polarity in forming vessels, and how these processes affect vessel function and are potentially perturbed in pathologies with vascular components.
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Affiliation(s)
| | - Victoria L. Bautch
- Department of Biology,
- McAllister Heart Institute,
- Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
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755
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Geudens I, Gerhardt H. Coordinating cell behaviour during blood vessel formation. Development 2011; 138:4569-83. [PMID: 21965610 DOI: 10.1242/dev.062323] [Citation(s) in RCA: 274] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The correct development of blood vessels is crucial for all aspects of tissue growth and physiology in vertebrates. The formation of an elaborate hierarchically branched network of endothelial tubes, through either angiogenesis or vasculogenesis, relies on a series of coordinated morphogenic events, but how individual endothelial cells adopt specific phenotypes and how they coordinate their behaviour during vascular patterning is unclear. Recent progress in our understanding of blood vessel formation has been driven by advanced imaging techniques and detailed analyses that have used a combination of powerful in vitro, in vivo and in silico model systems. Here, we summarise these models and discuss their advantages and disadvantages. We then review the different stages of blood vessel development, highlighting the cellular mechanisms and molecular players involved at each step and focusing on cell specification and coordination within the network.
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Affiliation(s)
- Ilse Geudens
- Vascular Patterning Laboratory, Vesalius Research Center, VIB, 3000 Leuven, Belgium
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756
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Arginine deiminase modulates endothelial tip cells via excessive synthesis of reactive oxygen species. Biochem Soc Trans 2011; 39:1376-81, suppl 2 p following 1382. [DOI: 10.1042/bst0391376] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
ADI (arginine deiminase), an enzyme that hydrolyses arginine, has been reported as an anti-angiogenesis agent. However, its molecular mechanism is unclear. We have demonstrated for the first time that ADI modulates the angiogenic activity of endothelial tip cells. By arginine depletion, ADI disturbs actin filament in endothelial tip cells, causing disordered migratory direction and decreased migration ability. Furthermore, ADI induces excessive synthesis of ROS (reactive oxygen species), and activates caspase 8-, but not caspase 9-, dependent apoptosis in endothelial cells. These findings provide a novel mechanism by which ADI inhibits tumour angiogenesis through modulating endothelial tip cells.
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757
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Chioda M, Peranzoni E, Desantis G, Papalini F, Falisi E, Solito S, Samantha S, Mandruzzato S, Bronte V. Myeloid cell diversification and complexity: an old concept with new turns in oncology. Cancer Metastasis Rev 2011; 30:27-43. [PMID: 21267772 DOI: 10.1007/s10555-011-9268-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Tumour development is accompanied by an enhanced haematopoiesis. This is not a widespread activation since only cells belonging to the myelo-monocytic compartment are expanded and mobilized from primary sites of haematopoiesis to other organs, reaching also the tumour stroma. This process occurs early during tumour formation but becomes more evident in advanced disease. Far from being a simple, unwanted consequence of cancer development, accumulation of myelo-monocytitc cells plays a role in tumour vascularization, local spreading, establishment of metastasis at distant sites, and contribute to create an environment unfavourable for the adoptive immunity against tumour-associated antigens. Myeloid populations involved in these process are likely different but many cells, expanded in primary and secondary lymphoid organs of tumour-bearing mice, share various levels of the CD11b and Gr-1 (Ly6C/G) markers. CD11b(+)Gr-1(+) cells are currently named myeloid-derived suppressor cells for their ability to inhibit T lymphocyte responses in tumour-bearing hosts. In this manuscript, we review the recent literature on tumour-conditioned myeloid subsets that assist tumour growth, both in mice and humans.
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758
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VEGFR-3 controls tip to stalk conversion at vessel fusion sites by reinforcing Notch signalling. Nat Cell Biol 2011; 13:1202-13. [PMID: 21909098 DOI: 10.1038/ncb2331] [Citation(s) in RCA: 245] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2010] [Accepted: 08/03/2011] [Indexed: 11/08/2022]
Abstract
Angiogenesis, the growth of new blood vessels, involves specification of endothelial cells to tip cells and stalk cells, which is controlled by Notch signalling, whereas vascular endothelial growth factor receptor (VEGFR)-2 and VEGFR-3 have been implicated in angiogenic sprouting. Surprisingly, we found that endothelial deletion of Vegfr3, but not VEGFR-3-blocking antibodies, postnatally led to excessive angiogenic sprouting and branching, and decreased the level of Notch signalling, indicating that VEGFR-3 possesses passive and active signalling modalities. Furthermore, macrophages expressing the VEGFR-3 and VEGFR-2 ligand VEGF-C localized to vessel branch points, and Vegfc heterozygous mice exhibited inefficient angiogenesis characterized by decreased vascular branching. FoxC2 is a known regulator of Notch ligand and target gene expression, and Foxc2(+/-);Vegfr3(+/-) compound heterozygosity recapitulated homozygous loss of Vegfr3. These results indicate that macrophage-derived VEGF-C activates VEGFR-3 in tip cells to reinforce Notch signalling, which contributes to the phenotypic conversion of endothelial cells at fusion points of vessel sprouts.
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759
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Stefater JA, Ren S, Lang RA, Duffield JS. Metchnikoff's policemen: macrophages in development, homeostasis and regeneration. Trends Mol Med 2011; 17:743-52. [PMID: 21890411 DOI: 10.1016/j.molmed.2011.07.009] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2011] [Revised: 07/26/2011] [Accepted: 07/29/2011] [Indexed: 12/27/2022]
Abstract
Over the past decade, modern genetic tools have permitted scientists to study the function of myeloid lineage cells, including macrophages, as never before. Macrophages were first detected more than a century ago as cells that ingested bacteria and other microbes, but it is now known that their functional roles are far more numerous. In this review, we focus on the prevailing functions of macrophages beyond their role in innate immunity. We highlight examples of macrophages acting as regulators of development, tissue homoeostasis, remodeling (the reorganization or renovation of existing tissues) and repair. We also detail how modern genetic tools have facilitated new insights into these mysterious cells.
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Affiliation(s)
- James A Stefater
- Visual Systems Group, Divisions of Pediatric Ophthalmology and Developmental Biology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229, USA
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760
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Kiefer F, Siekmann AF. The role of chemokines and their receptors in angiogenesis. Cell Mol Life Sci 2011; 68:2811-30. [PMID: 21479594 PMCID: PMC11115067 DOI: 10.1007/s00018-011-0677-7] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2010] [Revised: 03/09/2011] [Accepted: 03/22/2011] [Indexed: 12/21/2022]
Abstract
Chemokines are a vertebrate-specific group of small molecules that regulate cell migration and behaviour in diverse contexts. So far, around 50 chemokines have been identified in humans, which bind to 18 different chemokine receptors. These are members of the seven-transmembrane receptor family. Initially, chemokines were identified as modulators of the immune response. Subsequently, they were also shown to regulate cell migration during embryonic development. Here, we discuss the influence of chemokines and their receptors on angiogenesis, or the formation of new blood vessels. We highlight recent advances in our understanding of how chemokine signalling might directly influence endothelial cell migration. We furthermore examine the contributions of chemokine signalling in immune cells during this process. Finally, we explore possible implications for disease settings, such as chronic inflammation and tumour progression.
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Affiliation(s)
- Friedemann Kiefer
- Max Planck Institute for Molecular Biomedicine, Roentgenstr. 20, 48149 Muenster, Germany
| | - Arndt F. Siekmann
- Max Planck Institute for Molecular Biomedicine, Roentgenstr. 20, 48149 Muenster, Germany
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761
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Differential macrophage polarization promotes tissue remodeling and repair in a model of ischemic retinopathy. Sci Rep 2011; 1:76. [PMID: 22355595 PMCID: PMC3216563 DOI: 10.1038/srep00076] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Accepted: 08/08/2011] [Indexed: 11/24/2022] Open
Abstract
Diabetic retinopathy is the leading cause of visual loss in individuals under the age of 55. Umbilical cord blood (UCB)–derived myeloid progenitor cells have been shown to decrease neuronal damage associated with ischemia in the central nervous system. In this study we show that UCB-derived CD14+ progenitor cells provide rescue effects in a mouse model of ischemic retinopathy by promoting physiological angiogenesis and reducing associated inflammation. We use confocal microscopy to trace the fate of injected human UCB-derived CD14+ cells and PCR with species-specific probes to investigate their gene expression profile before and after injection. Metabolomic analysis measures changes induced by CD14+ cells. Our results demonstrate that human cells differentiate in vivo into M2 macrophages and induce the polarization of resident M2 macrophages. This leads to stabilization of the ischemia-injured retinal vasculature by modulating the inflammatory response, reducing oxidative stress and apoptosis and promoting tissue repair.
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762
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Erskine L, Reijntjes S, Pratt T, Denti L, Schwarz Q, Vieira JM, Alakakone B, Shewan D, Ruhrberg C. VEGF signaling through neuropilin 1 guides commissural axon crossing at the optic chiasm. Neuron 2011; 70:951-65. [PMID: 21658587 PMCID: PMC3114076 DOI: 10.1016/j.neuron.2011.02.052] [Citation(s) in RCA: 121] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/03/2011] [Indexed: 01/13/2023]
Abstract
During development, the axons of retinal ganglion cell (RGC) neurons must decide whether to cross or avoid the midline at the optic chiasm to project to targets on both sides of the brain. By combining genetic analyses with in vitro assays, we show that neuropilin 1 (NRP1) promotes contralateral RGC projection in mammals. Unexpectedly, the NRP1 ligand involved is not an axon guidance cue of the class 3 semaphorin family, but VEGF164, the neuropilin-binding isoform of the classical vascular growth factor VEGF-A. VEGF164 is expressed at the chiasm midline and is required for normal contralateral growth in vivo. In outgrowth and growth cone turning assays, VEGF164 acts directly on NRP1-expressing contralateral RGCs to provide growth-promoting and chemoattractive signals. These findings have identified a permissive midline signal for axons at the chiasm midline and provide in vivo evidence that VEGF-A is an essential axon guidance cue.
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Affiliation(s)
- Lynda Erskine
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Aberdeen, AB25 2ZD, UK.
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763
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Herbert SP, Stainier DY. Molecular control of endothelial cell behaviour during blood vessel morphogenesis. Nat Rev Mol Cell Biol 2011; 12:551-64. [PMID: 21860391 PMCID: PMC3319719 DOI: 10.1038/nrm3176] [Citation(s) in RCA: 741] [Impact Index Per Article: 57.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The vertebrate vasculature forms an extensive branched network of blood vessels that supplies tissues with nutrients and oxygen. During vascular development, coordinated control of endothelial cell behaviour at the levels of cell migration, proliferation, polarity, differentiation and cell-cell communication is critical for functional blood vessel morphogenesis. Recent data uncover elaborate transcriptional, post-transcriptional and post-translational mechanisms that fine-tune key signalling pathways (such as the vascular endothelial growth factor and Notch pathways) to control endothelial cell behaviour during blood vessel sprouting (angiogenesis). These emerging frameworks controlling angiogenesis provide unique insights into fundamental biological processes common to other systems, such as tissue branching morphogenesis, mechanotransduction and tubulogenesis.
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Affiliation(s)
- Shane P. Herbert
- Department of Biochemistry and Biophysics, Programs in Developmental and Stem Cell Biology, Genetics and Human Genetics, Cardiovascular Research Institute, University of California, San Francisco, California 94158, USA
- Multidisciplinary Cardiovascular Research Centre and Institute of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
- Faculty of Life Sciences, Michael Smith Building, University of Manchester, Oxford Road, Manchester M13 9PT, UK
| | - Didier Y.R. Stainier
- Department of Biochemistry and Biophysics, Programs in Developmental and Stem Cell Biology, Genetics and Human Genetics, Cardiovascular Research Institute, University of California, San Francisco, California 94158, USA
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764
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Fantin A, Schwarz Q, Davidson K, Normando EM, Denti L, Ruhrberg C. The cytoplasmic domain of neuropilin 1 is dispensable for angiogenesis, but promotes the spatial separation of retinal arteries and veins. Development 2011; 138:4185-91. [PMID: 21852397 PMCID: PMC3171219 DOI: 10.1242/dev.070037] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Neuropilin 1 (NRP1) is a transmembrane glycoprotein that is essential for blood vessel development in vertebrates. Best known for its ability to bind members of the vascular endothelial growth factor (VEGF) and class 3 semaphorin families through its extracellular domain, it also has a highly conserved cytoplasmic domain, which terminates in a SEA motif that binds the PDZ protein synectin/GIPC1/NIP. Previous studies in zebrafish embryos and tissue culture models raised the possibility that the SEA motif of NRP1 is essential for angiogenesis. Here, we describe the generation of mice that express a form of NRP1 that lacks the cytoplasmic domain and, therefore, the SEA motif (Nrp1cytoΔ/Δ mice). Our analysis of pre- and perinatal vascular development revealed that vasculogenesis and angiogenesis proceed normally in these mutants, demonstrating that the membrane-anchored extracellular domain is sufficient for vessel growth. By contrast, the NRP1 cytoplasmic domain is required for normal arteriovenous patterning, because arteries and veins crossed each other at an abnormally high frequency in the Nrp1cytoΔ/Δ retina, as previously reported for mice with haploinsufficient expression of VEGF in neural progenitors. At crossing sites, the artery was positioned anteriorly to the vein, and both vessels were embedded in a shared collagen sleeve. In human eyes, similar arteriovenous crossings are risk factors for branch retinal vein occlusion (BRVO), an eye disease in which compression of the vein by the artery disrupts retinal blood flow, causing local tissue hypoxia and impairing vision. Nrp1cytoΔ/Δ mice may therefore provide a suitable genetic model to study the aetiology of BRVO.
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Affiliation(s)
- Alessandro Fantin
- UCL Institute of Ophthalmology, University College London, London EC1V 9EL, UK
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765
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Vascularity of nongynecological leiomyosarcoma depends on colony-stimulating factor 1 but not on vascular endothelial growth factor. THE AMERICAN JOURNAL OF PATHOLOGY 2011; 179:1591-3. [PMID: 21839060 DOI: 10.1016/j.ajpath.2011.07.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Accepted: 07/06/2011] [Indexed: 11/22/2022]
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766
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Engineered blood vessel networks connect to host vasculature via wrapping-and-tapping anastomosis. Blood 2011; 118:4740-9. [PMID: 21835951 DOI: 10.1182/blood-2011-02-338426] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Rapid blood perfusion is critical for postimplantation survival of thick, prevascularized bioartificial tissues. Yet the mechanism by which implanted vascular networks inosculate, or anastomose, with the host vasculature has been unknown, making it difficult to develop optimized strategies for facilitating perfusion. Here we show that implanted vascular networks anastomose with host vessels through a previously unidentified process of "wrapping and tapping" between the engrafted endothelial cells (ECs) and the host vasculature. At the host-implant interface, implanted ECs first wrap around nearby host vessels and then cause basement membrane and pericyte reorganization and localized displacement of the underlying host endothelium. In this way, the implanted ECs replace segments of host vessels to divert blood flow to the developing implanted vascular network. The process is facilitated by high levels of matrix metalloproteinase-14 and matrix metalloproteinase-9 expressed by the wrapping ECs. These findings open the door to new strategies for improving perfusion of tissue grafts and may have implications for other physiologic and pathologic processes involving postnatal vasculogenesis.
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767
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Notch1 controls macrophage recruitment and Notch signaling is activated at sites of endothelial cell anastomosis during retinal angiogenesis in mice. Blood 2011; 118:3436-9. [PMID: 21795743 DOI: 10.1182/blood-2010-12-327015] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Notch is a critical regulator of angiogenesis, vascular differentiation, and vascular integrity. We investigated whether Notch signaling affects macrophage function during retinal angiogenesis in mice. Retinal macrophage recruitment and localization in mice with myeloid-specific loss of Notch1 was altered, as these macrophages failed to localize at the leading edge of the vascular plexus and at vascular branchpoints. Furthermore, these retinas were characterized by elongated endothelial cell sprouts that failed to anastomose with neighboring sprouts. Using Notch reporter mice, we demonstrate that retinal macrophages localize between Dll4-positive tip cells and at vascular branchpoints, and that these macrophages had activated Notch signaling. Taken together, these data demonstrate that Notch signaling in macrophages is important for their localization and interaction with endothelial cells during sprouting angiogenesis.
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768
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Ulrich F, Ma LH, Baker RG, Torres-Vázquez J. Neurovascular development in the embryonic zebrafish hindbrain. Dev Biol 2011; 357:134-51. [PMID: 21745463 DOI: 10.1016/j.ydbio.2011.06.037] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Revised: 06/10/2011] [Accepted: 06/13/2011] [Indexed: 01/05/2023]
Abstract
The brain is made of billions of highly metabolically active neurons whose activities provide the seat for cognitive, affective, sensory and motor functions. The cerebral vasculature meets the brain's unusually high demand for oxygen and glucose by providing it with the largest blood supply of any organ. Accordingly, disorders of the cerebral vasculature, such as congenital vascular malformations, stroke and tumors, compromise neuronal function and survival and often have crippling or fatal consequences. Yet, the assembly of the cerebral vasculature is a process that remains poorly understood. Here we exploit the physical and optical accessibility of the zebrafish embryo to characterize cerebral vascular development within the embryonic hindbrain. We find that this process is primarily driven by endothelial cell migration and follows a two-step sequence. First, perineural vessels with stereotypical anatomies are formed along the ventro-lateral surface of the neuroectoderm. Second, angiogenic sprouts derived from a subset of perineural vessels migrate into the hindbrain to form the intraneural vasculature. We find that these angiogenic sprouts reproducibly penetrate into the hindbrain via the rhombomere centers, where differentiated neurons reside, and that specific rhombomeres are invariably vascularized first. While the anatomy of intraneural vessels is variable from animal to animal, some aspects of the connectivity of perineural and intraneural vessels occur reproducibly within particular hindbrain locales. Using a chemical inhibitor of VEGF signaling we determine stage-specific requirements for this pathway in the formation of the hindbrain vasculature. Finally, we show that a subset of hindbrain vessels is aligned and/or in very close proximity to stereotypical neuron clusters and axon tracts. Using endothelium-deficient cloche mutants we show that the endothelium is dispensable for the organization and maintenance of these stereotypical neuron clusters and axon tracts in the early hindbrain. However, the cerebellum's upper rhombic lip and the optic tectum are abnormal in clo. Overall, this study provides a detailed, multi-stage characterization of early zebrafish hindbrain neurovascular development with cellular resolution up to the third day of age. This work thus serves as a useful reference for the neurovascular characterization of mutants, morphants and drug-treated embryos.
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Affiliation(s)
- Florian Ulrich
- Department of Developmental Genetics, Skirball Institute of Molecular Medicine, New York City, New York 10016, USA.
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769
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Krueger J, Liu D, Scholz K, Zimmer A, Shi Y, Klein C, Siekmann A, Schulte-Merker S, Cudmore M, Ahmed A, le Noble F. Flt1 acts as a negative regulator of tip cell formation and branching morphogenesis in the zebrafish embryo. Development 2011; 138:2111-20. [PMID: 21521739 DOI: 10.1242/dev.063933] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Endothelial tip cells guide angiogenic sprouts by exploring the local environment for guidance cues such as vascular endothelial growth factor (VegfA). Here we present Flt1 (Vegf receptor 1) loss- and gain-of-function data in zebrafish showing that Flt1 regulates tip cell formation and arterial branching morphogenesis. Zebrafish embryos expressed soluble Flt1 (sFlt1) and membrane-bound Flt1 (mFlt1). In Tg(flt1(BAC):yfp) × Tg(kdrl:ras-cherry)(s916) embryos, flt1:yfp was expressed in tip, stalk and base cells of segmental artery sprouts and overlapped with kdrl:cherry expression in these domains. flt1 morphants showed increased tip cell numbers, enhanced angiogenic behavior and hyperbranching of segmental artery sprouts. The additional arterial branches developed into functional vessels carrying blood flow. In support of a functional role for the extracellular VEGF-binding domain of Flt1, overexpression of sflt1 or mflt1 rescued aberrant branching in flt1 morphants, and overexpression of sflt1 or mflt1 in controls resulted in short arterial sprouts with reduced numbers of filopodia. flt1 morphants showed reduced expression of Notch receptors and of the Notch downstream target efnb2a, and ectopic expression of flt4 in arteries, consistent with loss of Notch signaling. Conditional overexpression of the notch1a intracellular cleaved domain in flt1 morphants restored segmental artery patterning. The developing nervous system of the trunk contributed to the distribution of Flt1, and the loss of flt1 affected neurons. Thus, Flt1 acts in a Notch-dependent manner as a negative regulator of tip cell differentiation and branching. Flt1 distribution may be fine-tuned, involving interactions with the developing nervous system.
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Affiliation(s)
- Janna Krueger
- Department of Angiogenesis and Cardiovascular Pathology, Max-Delbrueck Center for Molecular Medicine, D13125 Berlin, Germany
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770
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Eming SA, Hubbell JA. Extracellular matrix in angiogenesis: dynamic structures with translational potential. Exp Dermatol 2011; 20:605-13. [DOI: 10.1111/j.1600-0625.2011.01309.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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771
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Stefater JA, Lewkowich I, Rao S, Mariggi G, Carpenter AC, Burr AR, Fan J, Ajima R, Molkentin JD, Williams BO, Wills-Karp M, Pollard JW, Yamaguchi T, Ferrara N, Gerhardt H, Lang RA. Regulation of angiogenesis by a non-canonical Wnt-Flt1 pathway in myeloid cells. Nature 2011; 474:511-5. [PMID: 21623369 PMCID: PMC3214992 DOI: 10.1038/nature10085] [Citation(s) in RCA: 221] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2010] [Accepted: 03/30/2011] [Indexed: 01/01/2023]
Abstract
Myeloid cells are a feature of most tissues. Here we show that during development, retinal myeloid cells (RMCs) produce Wnt ligands to regulate blood vessel branching. In the mouse retina, where angiogenesis occurs postnatally1, somatic deletion in RMCs of the Wnt ligand transporter Wntless2,3 results in increased angiogenesis in the deeper layers. We also show that mutation of Wnt5a and Wnt11 results in increased angiogenesis and that these ligands elicit RMC responses via a non-canonical Wnt pathway. Using cultured myeloid-like cells and RMC somatic deletion of Flt1, we show that an effector of Wnt-dependent suppression of angiogenesis by RMCs is Flt1, a naturally occurring inhibitor of vascular endothelial growth factor (VEGF)4-6. These findings indicate that resident myeloid cells can use a non-canonical, Wnt-Flt1 pathway to suppress angiogenic branching.
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Affiliation(s)
- James A Stefater
- The Visual Systems Group, Division of Pediatric Ophthalmology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229, USA
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772
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Abstract
Angiopoietin-2 (ANG2), a ligand of the TIE2 receptor, modulates endothelial cell biology and destabilizes blood vessels to facilitate angiogenesis. Recent reports have shown that ANG2 inhibition, for example, by monoclonal antibodies, peptibodies, or CovX-Bodies, may achieve substantial antiangiogenic and antitumor responses in a variety of mouse tumor models, including spontaneous MMTV-PyMT mammary and RIP1-Tag2 pancreatic islet adenocarcinomas. There is also evidence that targeting the ANG2/TIE2 signaling pathway may inhibit the functions of TIE2-expressing macrophages (TEM), a tumor-associated macrophage subset endowed with proangiogenic activity in mouse tumor models. The clinical opportunities afforded by simultaneously targeting the effects of ANG2 on tumor angiogenesis and the proangiogenic activity of TEMs are discussed.
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Affiliation(s)
- Michele De Palma
- Angiogenesis and Tumor Targeting Unit, San Raffaele Scientific Institute, Milan, Italy.
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773
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Mazzieri R, Pucci F, Moi D, Zonari E, Ranghetti A, Berti A, Politi LS, Gentner B, Brown JL, Naldini L, De Palma M. Targeting the ANG2/TIE2 axis inhibits tumor growth and metastasis by impairing angiogenesis and disabling rebounds of proangiogenic myeloid cells. Cancer Cell 2011; 19:512-26. [PMID: 21481792 DOI: 10.1016/j.ccr.2011.02.005] [Citation(s) in RCA: 475] [Impact Index Per Article: 36.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2010] [Revised: 12/01/2010] [Accepted: 02/14/2011] [Indexed: 12/13/2022]
Abstract
Tumor-infiltrating myeloid cells convey proangiogenic programs that counteract the efficacy of antiangiogenic therapy. Here, we show that blocking angiopoietin-2 (ANG2), a TIE2 ligand and angiogenic factor expressed by activated endothelial cells (ECs), regresses the tumor vasculature and inhibits progression of late-stage, metastatic MMTV-PyMT mammary carcinomas and RIP1-Tag2 pancreatic insulinomas. ANG2 blockade did not inhibit recruitment of MRC1(+) TIE2-expressing macrophages (TEMs) but impeded their upregulation of Tie2, association with blood vessels, and ability to restore angiogenesis in tumors. Conditional Tie2 gene knockdown in TEMs was sufficient to decrease tumor angiogenesis. Our findings support a model wherein the ANG2-TIE2 axis mediates cell-to-cell interactions between TEMs and ECs that are important for tumor angiogenesis and can be targeted to induce effective antitumor responses.
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MESH Headings
- Adenoma, Islet Cell
- Angiopoietin-2/antagonists & inhibitors
- Angiopoietin-2/physiology
- Animals
- Cell Communication
- Endothelial Cells/physiology
- Gene Expression Regulation, Neoplastic
- Humans
- Macrophages/physiology
- Mammary Neoplasms, Experimental/blood supply
- Mammary Neoplasms, Experimental/pathology
- Mammary Neoplasms, Experimental/prevention & control
- Mice
- Mice, Inbred C57BL
- Myeloid Cells/physiology
- Neoplasm Metastasis/prevention & control
- Neoplasms, Experimental/blood supply
- Neoplasms, Experimental/prevention & control
- Neovascularization, Pathologic/prevention & control
- Neuroendocrine Tumors/prevention & control
- Receptor Protein-Tyrosine Kinases/antagonists & inhibitors
- Receptor Protein-Tyrosine Kinases/physiology
- Receptor, TIE-2
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Affiliation(s)
- Roberta Mazzieri
- Angiogenesis and Tumor Targeting Research Unit, San Raffaele Scientific Institute, Milan, Italy
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774
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Welford AF, Biziato D, Coffelt SB, Nucera S, Fisher M, Pucci F, Di Serio C, Naldini L, De Palma M, Tozer GM, Lewis CE. TIE2-expressing macrophages limit the therapeutic efficacy of the vascular-disrupting agent combretastatin A4 phosphate in mice. J Clin Invest 2011; 121:1969-73. [PMID: 21490397 DOI: 10.1172/jci44562] [Citation(s) in RCA: 171] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2010] [Accepted: 01/26/2011] [Indexed: 11/17/2022] Open
Abstract
Vascular-disrupting agents (VDAs) such as combretastatin A4 phosphate (CA4P) selectively disrupt blood vessels in tumors and induce tumor necrosis. However, tumors rapidly repopulate after treatment with such compounds. Here, we show that CA4P-induced vessel narrowing, hypoxia, and hemorrhagic necrosis in murine mammary tumors were accompanied by elevated tumor levels of the chemokine CXCL12 and infiltration by proangiogenic TIE2-expressing macrophages (TEMs). Inhibiting TEM recruitment to CA4P-treated tumors either by interfering pharmacologically with the CXCL12/CXCR4 axis or by genetically depleting TEMs in tumor-bearing mice markedly increased the efficacy of CA4P treatment. These data suggest that TEMs limit VDA-induced tumor injury and represent a potential target for improving the clinical efficacy of VDA-based therapies.
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Affiliation(s)
- Abigail F Welford
- Tumour Microcirculation Group, The University of Sheffield Medical School, Sheffield, UK
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775
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Affiliation(s)
- Gian Paolo Fadini
- Department of Clinical and Experimental Medicine, Metabolic Division, University of Padova, Medical School-Padova, Italy.
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776
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Squadrito ML, De Palma M. Macrophage regulation of tumor angiogenesis: Implications for cancer therapy. Mol Aspects Med 2011; 32:123-45. [DOI: 10.1016/j.mam.2011.04.005] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2011] [Accepted: 04/27/2011] [Indexed: 12/24/2022]
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777
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Bone marrow-derived cells serve as proangiogenic macrophages but not endothelial cells in wound healing. Blood 2011; 117:5264-72. [PMID: 21411758 DOI: 10.1182/blood-2011-01-330720] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Bone marrow-derived cells (BMDCs) contribute to postnatal vascular growth by differentiating into endothelial cells or secreting angiogenic factors. However, the extent of their endothelial differentiation highly varies according to the angiogenic models used. Wound healing is an intricate process in which the skin repairs itself after injury. As a process also observed in cancer progression, neoangiogenesis into wound tissues is profoundly involved in this healing process, suggesting the contribution of BMDCs. However, the extent of the differentiation of BMDCs to endothelial cells in wound healing is unclear. In this study, using the green fluorescent protein-bone marrow chim-eric experiment and high resolution confocal microscopy at a single cell level, we observed no endothelial differentiation of BMDCs in 2 acute wound healing models (dorsal excisional wound and ear punch) and a chronic wound healing model (decubitus ulcer). Instead, a major proportion of BMDCs were macrophages. Indeed, colony-stimulating factor 1 (CSF-1) inhibition depleted approximately 80% of the BMDCs at the wound healing site. CSF-1-mutant (CSF-1(op/op)) mice showed significantly reduced neoangiogenesis into the wound site, supporting the substantial role of BMDCs as macrophages. Our data show that the proangiogenic effects of macrophages, but not the endothelial differentiation, are the major contribution of BMDCs in wound healing.
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778
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Saha P, Humphries J, Modarai B, Mattock K, Waltham M, Evans CE, Ahmad A, Patel AS, Premaratne S, Lyons OTA, Smith A. Leukocytes and the natural history of deep vein thrombosis: current concepts and future directions. Arterioscler Thromb Vasc Biol 2011; 31:506-12. [PMID: 21325673 PMCID: PMC3079895 DOI: 10.1161/atvbaha.110.213405] [Citation(s) in RCA: 131] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2010] [Accepted: 12/21/2010] [Indexed: 12/24/2022]
Abstract
Observational studies have shown that inflammatory cells accumulate within the thrombus and surrounding vein wall during the natural history of venous thrombosis. More recent studies have begun to unravel the mechanisms that regulate this interaction and have confirmed that thrombosis and inflammation are intimately linked. This review outlines our current knowledge of the complex relationship between inflammatory cell activity and venous thrombosis and highlights new areas of research in this field. A better understanding of this relationship could lead to the development of novel therapeutic targets that inhibit thrombus formation or promote its resolution.
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Affiliation(s)
- Prakash Saha
- Kings College London, British Heart Foundation Centre of Research Excellence and National Institute for Health Research Biomedical Research Centre at Kings Health Partners, Academic Department of Surgery, St Thomas' Hospital, London, United Kingdom
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779
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Gray C, Loynes CA, Whyte MKB, Crossman DC, Renshaw SA, Chico TJA. Simultaneous intravital imaging of macrophage and neutrophil behaviour during inflammation using a novel transgenic zebrafish. Thromb Haemost 2011; 105:811-9. [PMID: 21225092 DOI: 10.1160/th10-08-0525] [Citation(s) in RCA: 150] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Accepted: 09/08/2010] [Indexed: 11/05/2022]
Abstract
The zebrafish is an outstanding model for intravital imaging of inflammation due to its optical clarity and the ability to express fluorescently labelled specific cell types by transgenesis. However, although several transgenic labelling myeloid cells exist, none allow distinction of macrophages from neutrophils. This prevents simultaneous imaging and examination of the individual contributions of these important leukocyte subtypes during inflammation. We therefore used Bacterial Artificial Chromosome (BAC) recombineering to generate a transgenic Tg(fms:GAL4.VP16)i186 , in which expression of the hybrid transcription factor Gal4-VP16 is driven by the fms (CSF1R) promoter. This was then crossed to a second transgenic expressing a mCherry-nitroreductase fusion protein under the control of the Gal4 binding site (the UAS promoter), allowing intravital imaging of mCherry-labelled macrophages. Further crossing this compound transgenic with the neutrophil transgenic Tg(mpx:GFP)i114 allowed clear distinction between macrophages and neutrophils and simultaneous imaging of their recruitment and behaviour during inflammation. Compared with neutrophils, macrophages migrate significantly more slowly to an inflammatory stimulus. Neutrophil number at a site of tissue injury peaked around 6 hours post injury before resolving, while macrophage recruitment increased until at least 48 hours. We show that macrophages were effectively ablated by addition of the prodrug metronidazole, with no effect on neutrophil number. Crossing with Tg(Fli1:GFP)y1 transgenic fish enabled intravital imaging of macrophage interaction with endothelium for the first time, revealing that endothelial contact is associated with faster macrophage migration. Tg(fms:GAL4.VP16)i186 thus provides a powerful tool for intravital imaging and functional manipulation of macrophage behaviour during inflammation.
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Affiliation(s)
- C Gray
- MRC Centre for Developmental and Biomedical Genetics, University of Sheffield, Sheffield, UK
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780
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Rymo SF, Gerhardt H, Wolfhagen Sand F, Lang R, Uv A, Betsholtz C. A two-way communication between microglial cells and angiogenic sprouts regulates angiogenesis in aortic ring cultures. PLoS One 2011; 6:e15846. [PMID: 21264342 PMCID: PMC3018482 DOI: 10.1371/journal.pone.0015846] [Citation(s) in RCA: 167] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Accepted: 11/25/2010] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND Myeloid cells have been associated with physiological and pathological angiogenesis, but their exact functions in these processes remain poorly defined. Monocyte-derived tissue macrophages of the CNS, or microglial cells, invade the mammalian retina before it becomes vascularized. Recent studies correlate the presence of microglia in the developing CNS with vascular network formation, but it is not clear whether the effect is directly caused by microglia and their contact with the endothelium. METHODOLOGY/PRINCIPAL FINDINGS We combined in vivo studies of the developing mouse retina with in vitro studies using the aortic ring model to address the role of microglia in developmental angiogenesis. Our in vivo analyses are consistent with previous findings that microglia are present at sites of endothelial tip-cell anastomosis, and genetic ablation of microglia caused a sparser vascular network associated with reduced number of filopodia-bearing sprouts. Addition of microglia in the aortic ring model was sufficient to stimulate vessel sprouting. The effect was independent of physical contact between microglia and endothelial cells, and could be partly mimicked using microglial cell-conditioned medium. Addition of VEGF-A promoted angiogenic sprouts of different morphology in comparison with the microglial cells, and inhibition of VEGF-A did not affect the microglia-induced angiogenic response, arguing that the proangiogenic factor(s) released by microglia is distinct from VEGF-A. Finally, microglia exhibited oriented migration towards the vessels in the aortic ring cultures. CONCLUSIONS/SIGNIFICANCE Microglia stimulate vessel sprouting in the aortic ring cultures via a soluble microglial-derived product(s), rather than direct contact with endothelial cells. The observed migration of microglia towards the growing sprouts suggests that their position near endothelial tip-cells could result from attractive cues secreted by the vessels. Our data reveals a two-way communication between microglia and vessels that depends on soluble factors and should extend the understanding of how microglia promote vascular network formation.
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Affiliation(s)
- Simin F Rymo
- Institute of Biomedicine, University of Gothenburg, Gothenburg, Sweden
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781
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Abstract
After recruitment to the wound bed, monocytes differentiate into macrophages. Macrophages play a central role in all stages of wound healing and orchestrate the wound healing process. Their functional phenotype is dependent on the wound microenvironment, which changes during healing, hereby altering macrophage phenotype. During the early and short inflammatory phase macrophages exert pro-inflammatory functions like antigen-presenting, phagocytosis and the production of inflammatory cytokines and growth factors that facilitate the wound healing process. As such, the phenotype of wound macrophages in this phase is probably the classically activated or the so-called M1 phenotype. During the proliferative phase, macrophages stimulate proliferation of connective, endothelial and epithelial tissue directly and indirectly. Especially fibroblasts, keratinocytes and endothelial cells are stimulated by macrophages during this phase to induce and complete ECM formation, reepithelialization and neovascularization. Subsequently, macrophages can change the composition of the ECM both during angiogenesis and in the remodelling phase by release of degrading enzymes and by synthesizing ECM molecules. This suggests an important role for alternatively activated macrophages in this phase of wound healing. Pathological functioning of macrophages in the wound healing process can result in derailed wound healing, like the formation of ulcers, chronic wounds, hypertrophic scars and keloids. However, the exact role of macrophages in these processes is still incompletely understood. For treating wound repair disorders more should be elucidated on the role of macrophages in these conditions, especially their functional phenotype, to find more therapeutic opportunities. This review summarizes macrophage function in skin injury repair, thereby providing more insight in macrophage function in wound healing and possible interventions in this process.
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782
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Abstract
The mammalian lymphatic vasculature has an important function in the maintenance of tissue fluid homeostasis, absorption of dietary lipids, and immune surveillance. The lymphatic vessels are also recruited by many tumors as primary routes for metastasis and mediate immune responses in inflammatory diseases, whereas dysfunction of the lymphatic drainage leads to lymphedema. The characterization of a lymphatic vasculature in zebrafish has made the advantages of this small model organism, the suitability for intravital time-lapse imaging of developmental processes and the amenability for chemical and forward genetic screens, available to lymphatic vascular research. Here we review our current understanding of embryonic lymphangiogenesis in zebrafish, its molecular and anatomical similarities to mammalian lymphatic vascular development, and the possibilities zebrafish offers to complement mouse models and cell culture assays in the lymphangiogenesis field.
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783
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Gordon EJ, Rao S, Pollard JW, Nutt SL, Lang RA, Harvey NL. Macrophages define dermal lymphatic vessel calibre during development by regulating lymphatic endothelial cell proliferation. Development 2010; 137:3899-910. [PMID: 20978081 DOI: 10.1242/dev.050021] [Citation(s) in RCA: 115] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Macrophages have been suggested to stimulate neo-lymphangiogenesis in settings of inflammation via two potential mechanisms: (1) acting as a source of lymphatic endothelial progenitor cells via the ability to transdifferentiate into lymphatic endothelial cells and be incorporated into growing lymphatic vessels; and (2) providing a crucial source of pro-lymphangiogenic growth factors and proteases. We set out to establish whether cells of the myeloid lineage are important for development of the lymphatic vasculature through either of these mechanisms. Here, we provide lineage tracing evidence to demonstrate that lymphatic endothelial cells arise independently of the myeloid lineage during both embryogenesis and tumour-stimulated lymphangiogenesis in the mouse, thus excluding macrophages as a source of lymphatic endothelial progenitor cells in these settings. In addition, we demonstrate that the dermal lymphatic vasculature of PU.1(-/-) and Csf1r(-/-) macrophage-deficient mouse embryos is hyperplastic owing to elevated lymphatic endothelial cell proliferation, suggesting that cells of the myeloid lineage provide signals that act to restrain lymphatic vessel calibre in the skin during development. In contrast to what has been demonstrated in settings of inflammation, macrophages do not comprise the principal source of pro-lymphangiogenic growth factors, including VEGFC and VEGFD, in the embryonic dermal microenvironment, illustrating that the sources of patterning and proliferative signals driving embryonic and disease-stimulated lymphangiogenesis are likely to be distinct.
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Affiliation(s)
- Emma J Gordon
- Division of Haematology, Centre for Cancer Biology, SA Pathology, Adelaide, 5000, Australia
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784
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Caposio P, Orloff SL, Streblow DN. The role of cytomegalovirus in angiogenesis. Virus Res 2010; 157:204-11. [PMID: 20869406 DOI: 10.1016/j.virusres.2010.09.011] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2010] [Revised: 09/17/2010] [Accepted: 09/17/2010] [Indexed: 01/02/2023]
Abstract
Human cytomegalovirus (HCMV) infection has been associated with the acceleration of vascular disease including atherosclerosis and transplant associated vasculopathy in solid organ transplants. HCMV promotes vascular disease at many of the different stages of the disease development. These include the initial injury phase, enhancing the response to injury and inflammation, as well as by increasing SMC hyperplasia and foamy macrophage cell formation. Angiogenesis is a critical process involved in the development of vascular diseases. Recently, HCMV has been shown to induce angiogenesis and this process is thought to contribute to HCMV-accelerated vascular disease and may also be important for HCMV-enhanced tumor formation. This review will highlight the role of HCMV in promoting angiogenesis.
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Affiliation(s)
- Patrizia Caposio
- Department of Molecular Microbiology & Immunology and The Vaccine & Gene Therapy Institute, Oregon Health & Science University, Portland, OR 97239, USA
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785
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Biswas SK, Mantovani A. Macrophage plasticity and interaction with lymphocyte subsets: cancer as a paradigm. Nat Immunol 2010; 11:889-96. [PMID: 20856220 DOI: 10.1038/ni.1937] [Citation(s) in RCA: 2736] [Impact Index Per Article: 195.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Plasticity is a hallmark of cells of the myelomonocytic lineage. In response to innate recognition or signals from lymphocyte subsets, mononuclear phagocytes undergo adaptive responses. Shaping of monocyte-macrophage function is an essential component of resistance to pathogens, tissue damage and repair. The orchestration of myelomonocytic cell function is a key element that links inflammation and cancer and provides a paradigm for macrophage plasticity and function. A better understanding of the molecular basis of myelomonocytic cell plasticity will open new vistas in immunopathology and therapeutic intervention.
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Affiliation(s)
- Subhra K Biswas
- Singapore Immunology Network, Agency for Science, Technology & Research, Singapore.
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786
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Watt SM, Athanassopoulos A, Harris AL, Tsaknakis G. Human endothelial stem/progenitor cells, angiogenic factors and vascular repair. J R Soc Interface 2010; 7 Suppl 6:S731-51. [PMID: 20843839 DOI: 10.1098/rsif.2010.0377.focus] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Neovascularization or new blood vessel formation is of utmost importance not only for tissue and organ development and for tissue repair and regeneration, but also for pathological processes, such as tumour development. Despite this, the endothelial lineage, its origin, and the regulation of endothelial development and function either intrinsically from stem cells or extrinsically by proangiogenic supporting cells and other elements within local and specific microenvironmental niches are still not fully understood. There can be no doubt that for most tissues and organs, revascularization represents the holy grail for tissue repair, with autologous endothelial stem/progenitor cells, their proangiogenic counterparts and the products of these cells all being attractive targets for therapeutic intervention. Historically, a great deal of controversy has surrounded the identification and origin of cells and factors that contribute to revascularization, the use of such cells or their products as biomarkers to predict and monitor tissue damage and repair or tumour progression and therapeutic responses, and indeed their efficacy in revascularizing and repairing damaged tissues. Here, we will review the role of endothelial progenitor cells and of supporting proangiogenic cells and their products, principally in humans, as diagnostic and therapeutic agents for wound repair and tissue regeneration.
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Affiliation(s)
- Suzanne M Watt
- Stem Cell Laboratory and Stem Cells and Immunotherapies, NHS Blood and Transplant, John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK.
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787
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Ruhrberg C, De Palma M. A double agent in cancer: Deciphering macrophage roles in human tumors. Nat Med 2010; 16:861-2. [DOI: 10.1038/nm0810-861] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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788
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Qualls JE, Murray PJ. A double agent in cancer: Stopping macrophages wounds tumors. Nat Med 2010; 16:863-4. [DOI: 10.1038/nm0810-863] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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789
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Endothelial progenitor cells: quo vadis? J Mol Cell Cardiol 2010; 50:266-72. [PMID: 20673769 DOI: 10.1016/j.yjmcc.2010.07.009] [Citation(s) in RCA: 172] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2010] [Revised: 07/13/2010] [Accepted: 07/14/2010] [Indexed: 01/13/2023]
Abstract
The term endothelial progenitor cell (EPC) was coined to refer to circulating cells that displayed the ability to display cell surface antigens similar to endothelial cells in vitro, to circulate and lodge in areas of ischemia or vascular injury, and to facilitate the repair of damaged blood vessels or augment development of new vessels as needed by a tissue. More than 10 years after the first report, the term EPC is used to refer to a host of circulating cells that display some or all of the qualities indicated above, however, essentially all of the cells are now known to be members of the hematopoietic lineage. The exception is a rare viable circulating endothelial cell with clonal proliferative potential that displays the ability to spontaneously form inosculating human blood vessels upon implantation into immunodeficient murine host tissues. This paper will review the current lineage relationships among all the cells called EPC and will propose that the term EPC be retired and that each of the circulating cell subsets be referred to according to the terms already existent for each subset. This article is part of a special issue entitled, "Cardiovascular Stem Cells Revisited".
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790
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