Papers by Christiana Ruhrberg
Angiogenesis, Apr 13, 2022
Blood vessels form vast networks in all vertebrate organs to sustain tissue growth, repair and ho... more Blood vessels form vast networks in all vertebrate organs to sustain tissue growth, repair and homeostatic metabolism, but they also contribute to a range of diseases with neovascularisation. It is, therefore, important to define the molecular mechanisms that underpin blood vessel growth. The receptor tyrosine kinase KIT is required for the normal expansion of hematopoietic progenitors that arise during embryogenesis from hemogenic endothelium in the yolk sac and dorsal aorta. Additionally, KIT has been reported to be expressed in endothelial cells during embryonic brain vascularisation and has been implicated in pathological angiogenesis. However, it is neither known whether KIT expression is widespread in normal organ endothelium nor whether it promotes blood vessel growth in developing organs. Here, we have used single-cell analyses to show that KIT is expressed in endothelial cell subsets of several organs, both in the adult and in the developing embryo. Knockout mouse analyses revealed that KIT is dispensable for vascularisation of growing organs in the midgestation embryo, including the lung, liver and brain. By contrast, vascular changes emerged during late-stage embryogenesis in these organs from KIT-deficient embryos, concurrent with severe erythrocyte deficiency and growth retardation. These findings suggest that KIT is not required for developmental tissue vascularisation in physiological conditions, but that KIT deficiency causes foetal anaemia at late gestation and thereby pathological vascular remodelling.
Erratum: Neurophilin 1 and 2 control cranial gangliogenesis and axon guidance through neural crest cells (Development (2009) vol. 135 (1605-1613))
Development, Jan 15, 2009
Angiogenesis, Apr 6, 2021
Lymphatic vessels have critical roles in both health and disease and their study is a rapidly evo... more Lymphatic vessels have critical roles in both health and disease and their study is a rapidly evolving area of vascular biology. The consensus on how the first lymphatic vessels arise in the developing embryo has recently shifted. Originally, they were thought to solely derive by sprouting from veins. Since then, several studies have uncovered novel cellular mechanisms and a diversity of contributing cell lineages in the formation of organ lymphatic vasculature. Here, we review the key mechanisms and cell lineages contributing to lymphatic development, discuss the advantages and limitations of experimental techniques used for their study and highlight remaining knowledge gaps that require urgent attention. Emerging technologies should accelerate our understanding of how lymphatic vessels develop normally and how they contribute to disease.
Nature, Sep 26, 2018
The earliest blood vessels in the mammalian embryo are formed when endothelial cells (ECs) differ... more The earliest blood vessels in the mammalian embryo are formed when endothelial cells (ECs) differentiate from angioblasts and coalesce into tubular networks. Thereafter, the endothelium is thought to expand solely by proliferation of pre-existing ECs. Here we show that the earliest precursors of erythrocytes, megakaryocytes and macrophages, the yolk sac-derived erythromyeloid progenitors (EMPs), provide a complementary source of ECs that are recruited into preexisting vasculature. Whereas a first wave of yolk sac-resident EMPs contributes ECs to the yolk sac endothelium, a second wave of EMPs colonises the embryo and contributes ECs to intraembryonic endothelium in multiple organs, where they persist into adulthood. By demonstrating that EMPs constitute a hitherto unrecognised source of ECs, we reveal that embryonic blood vascular endothelium expands in a dual mechanism that involves both the proliferation of pre-existing ECs and the incorporation of ECs derived from hematopoietic precursors. Blood vessels distribute oxygen, nutrients, hormones and immune cells through the vertebrate body and help remove waste molecules. Accordingly, functional blood vessel formation during embryogenesis is a prerequisite for vertebrate life. Endothelial cells (ECs) form the inner lining of blood vessels; they first arise from mesenchymal precursors termed Users may view, print, copy, and download text and data-mine the content in such documents, for the purposes of academic research, subject always to the full Conditions of use:
Journal of Clinical Investigation, Jun 8, 2015
Springer eBooks, 2022
Blood vessel growth is a fundamental process for organ development and wound healing but is also ... more Blood vessel growth is a fundamental process for organ development and wound healing but is also associated with ischemic diseases and cancer. The growth of new blood vessels from preexisting vasculature, termed sprouting angiogenesis, is the predominant mode of blood vessel growth in central nervous system vascularisation and pathological vessel growth. Accordingly, studying the molecular and cellular mechanisms of angiogenesis holds the promise to find novel therapeutic targets to stimulate new vessel formation in ischemic tissues or inhibit pathological vessel growth in disease. The embryonic mouse hindbrain provides an excellent model to study sprouting angiogenesis in vivo by histochemical or fluorescent wholemount immunolabelling, thus allowing high-resolution image capture of nascent vasculature and subsequent quantification of relevant angiogenic parameters. This chapter describes how to use the mouse embryonic hindbrain as a model to study physiological angiogenesis, including detailed protocols for hindbrain dissection, wholemount staining, and angiogenic parameters analysis.
Development (Cambridge, England), 2017
Visual information is relayed from the eye to the brain via retinal ganglion cell (RGC) axons. Mi... more Visual information is relayed from the eye to the brain via retinal ganglion cell (RGC) axons. Mice lacking NRP1 or NRP1-binding VEGF-A isoforms have defective RGC axon organisation alongside brain vascular defects. It is not known whether axonal defects are caused exclusively by defective VEGF-A signalling in RGCs or are exacerbated by abnormal vascular morphology. Targeted NRP1 ablation in RGCs with a Brn3b(Cre) knock-in allele reduced axonal midline crossing at the optic chiasm and optic tract fasciculation. In contrast, Tie2-Cre-mediated endothelial NRP1 ablation induced axon exclusion zones in the optic tracts without impairing axon crossing. Similar defects were observed in Vegfa(120/120) and Vegfa(188/188) mice, which have vascular defects as a result of their expression of single VEGF-A isoforms. Ectopic midline vascularisation in endothelial Nrp1 and Vegfa(188/188) mutants caused additional axonal exclusion zones within the chiasm. As in vitro and in vivo assays demonstrate...
Acta Neuropathologica, Nov 6, 2019
The vertebrate CNS is surrounded by the meninges, a protective barrier comprised of the outer dur... more The vertebrate CNS is surrounded by the meninges, a protective barrier comprised of the outer dura mater and the inner leptomeninges, which includes the arachnoid and pial layers. While the dura mater contains lymphatic vessels, no conventional lymphatics have been found within the brain or leptomeninges. However, non-lumenized cells called Brain/Mural Lymphatic Endothelial Cells or Fluorescent Granule Perithelial cells (muLECs/BLECs/FGPs) that share a developmental program and gene expression with peripheral lymphatic vessels have been described in the meninges of zebrafish. Here we identify a structurally and functionally similar cell type in the mammalian leptomeninges that we name Leptomeningeal Lymphatic Endothelial Cells (LLEC). As in zebrafish, LLECs express multiple lymphatic markers, containing very large, spherical inclusions, and develop independently from the meningeal macrophage lineage. Mouse LLECs also internalize macromolecules from the cerebrospinal fluid, including Amyloid-β, the toxic driver of Alzheimer's disease progression. Finally, we identify morphologically similar cells co-expressing LLEC markers in human post-mortem leptomeninges. Given that LLECs share molecular, morphological, and functional characteristics with both lymphatics and macrophages, we propose they represent a novel, evolutionary conserved cell type with potential roles in homeostasis and immune organization of the meninges.
Authors
d Hypoxia within the nerve bridge is selectively sensed by macrophages d Macrophage-derived VEGF-... more d Hypoxia within the nerve bridge is selectively sensed by macrophages d Macrophage-derived VEGF-A induces a polarized vasculature within the bridge d Blood vessels are used as tracks to direct Schwann cell migration across the wound d Macrophage-induced blood vessels are essential for nerve
Regulation and Function of Cardiac Neural Crest Cells ☆
Reference Module in Biomedical Sciences, 2018
The cardiac neural crest cells (NCCs), also known as circumpharyngeal NCCs, make an essential con... more The cardiac neural crest cells (NCCs), also known as circumpharyngeal NCCs, make an essential contribution to cardiovascular development in vertebrates. These cells delaminate from the developing neural tube to migrate into the pharyngeal arches (PAs) of the embryo, where they induce the remodeling of the pharyngeal arch arteries (PAAs) into the great vessels that distribute blood from the heart into the lung and systemic vasculature. A subset of cardiac NCCs continues to migrate into the cardiac outflow tract (OFT) to induce its septation into the arterial and pulmonary trunks that connect to the remodeled PAAs. Owing to their essential role in cardiovascular development, cardiac NCC defects cause congenital heart disease. In this article, we describe current knowledge of the molecular and cellular mechanisms that underlie cardiac NCC function.
F1000 - Post-publication peer review of the biomedical literature, 2018
Excess dietary lipid uptake causes obesity, a major global health problem. Enterocyte-absorbed li... more Excess dietary lipid uptake causes obesity, a major global health problem. Enterocyte-absorbed lipids are packaged into chylomicrons, which enter the bloodstream through intestinal lymphatic vessels called lacteals. Here, we show that preventing lacteal chylomicron uptake by inducible endothelial genetic deletion of Neuropilin1 (Nrp1) and Vascular endothelial growth factor receptor
axons. (A) Coronal section of an E14.5 wild type retina, stained by double immunofluorescence wit... more axons. (A) Coronal section of an E14.5 wild type retina, stained by double immunofluorescence with antibodies specific for NRP1 (red) and the RGC marker BRN3A (green); the section was counterstained with the nuclear marker DAPI (blue). (B) Higher magnification of the boxed region in (A); red and green channels are shown in (B’), the red channel only is shown in (B”). NRP1-positive RGC axons are indicated with feathered arrows, choroidal vessels with clear arrowheads. White bracket indicates the RGC layer. Scale bar: 100 µm (A). 1 Supplemental Figure 2, related to Figure 2. Anterograde labelling technique and midline architecture in Nrp1-null mutants. (A) Illustration of the anterograde DiI labelling technique, which was used to visualise the projection of RGC axons. A crystal of DiI was placed on the optic disc of one retina. After the dye had diffused along the axons, the brain was dissected and imaged, ventral side up, with a fluorescent stereomicroscope to reveal RGC axons in the...
Video Article Mouse Hindbrain Ex Vivo Culture to Study Facial Branchiomotor Neuron Migration
e51397, doi:10.3791/51397 (2014). Embryonic neurons are born in the ventricular zone of the brain... more e51397, doi:10.3791/51397 (2014). Embryonic neurons are born in the ventricular zone of the brain, but subsequently migrate to new destinations to reach appropriate targets. Deciphering the molecular signals that cooperatively guide neuronal migration in the embryonic brain is therefore important to understand how the complex neural networks form which later support postnatal life. Facial branchiomotor (FBM) neurons in the mouse embryo hindbrain migrate from rhombomere (r) 4 caudally to form the paired facial nuclei in the r6-derived region of the hindbrain. Here we provide a detailed protocol for wholemount ex vivo culture of mouse embryo hindbrains suitable to investigate the signaling pathways that regulate FBM migration. In this method, hindbrains of E11.5 mouse embryos are dissected and cultured in an open book preparation on cell culture inserts for 24 hr. During this time, FBM neurons migrate caudally towards r6 and can be exposed to function-blocking antibodies and small mol...
VEGF guides angiogenic sprouting utilizing endothelial tip cell filopodia
Cerebral Cortex, 2018
Vascular endothelial growth factor (Vegfa) is essential for promoting the vascularization of the ... more Vascular endothelial growth factor (Vegfa) is essential for promoting the vascularization of the embryonic murine forebrain. In addition, it directly influences neural development, although its role in the forming forebrain is less well elucidated. It was recently suggested that Vegfa may influence the development of GABAergic interneurons, inhibitory cells with crucial signaling roles in cortical neuronal circuits. However, the mechanism by which it affects interneuron development remains unknown. Here we investigated the developmental processes by which Vegfa may influence cortical interneuron development by analyzing transgenic mice that ubiquitously express the Vegfa120 isoform to perturb its signaling gradient. We found that interneurons reach the dorsal cortex at mid phases of corticogenesis despite an aberrant vascular network. Instead, endothelial ablation of Vegfa alters cortical interneuron numbers, their intracortical distribution and spatial proximity to blood vessels. We show for the first time that vascular-secreted guidance factors promote early-migrating interneurons in the intact forebrain in vivo and identify a novel role for vascular-Vegfa in this process.
Faculty of 1000 evaluation for Vessel maturation schedule determines vulnerability to neuronal injuries of prematurity
F1000 - Post-publication peer review of the biomedical literature, 2015
F1000 - Post-publication peer review of the biomedical literature, 2016
Author contribution. FG, EM designed the study and wrote the manuscript. EM, IB performed cell so... more Author contribution. FG, EM designed the study and wrote the manuscript. EM, IB performed cell sorting, flow cytometry, fatemapping, immunostaining experiments and RNA-seq analysis on Id3-deficicient and control Kupffer cells. LC and CEJG helped with analysis of Tnfrsf11a Cre+ ; Rosa26 LSL-YFP mice. EGP assisted with the design of cell sorting experiments. MF designed and prepared bulk RNA-seq libraries. FH, JK, CB performed primary and differential analysis of the bulk RNA-seq data. KH and MB generated single-cell RNA-seq libraries and performed single-cell RNA-seq, PG, MB and JLS analyzed single cell RNA-seq data. All authors contributed to the manuscript.
Proceedings of the National Academy of Sciences of the United States of America, Jan 22, 2016
In the adult rodent brain, new neurons are born in two germinal regions that are associated with ... more In the adult rodent brain, new neurons are born in two germinal regions that are associated with blood vessels, and blood vessels and vessel-derived factors are thought to regulate the activity of adult neural stem cells. Recently, it has been proposed that a vascular niche also regulates prenatal neurogenesis. Here we identify the mouse embryo hindbrain as a powerful model to study embryonic neurogenesis and define the relationship between neural progenitor cell (NPC) behavior and vessel growth. Using this model, we show that a subventricular vascular plexus (SVP) extends through a hindbrain germinal zone populated by NPCs whose peak mitotic activity follows a surge in SVP growth. Hindbrains genetically defective in SVP formation owing to constitutive NRP1 loss showed a premature decline in both NPC activity and hindbrain growth downstream of precocious cell cycle exit, premature neuronal differentiation, and abnormal mitosis patterns. Defective regulation of NPC activity was not o...
Video 2 Tie2-Cre Nrp1 hindbrain dissection.mpg
Legs at odd angles-a mutation in dynein that impairs the navigation of motor neurons
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Papers by Christiana Ruhrberg