1
|
Wen L, Yan W, Zhu L, Tang C, Wang G. The role of blood flow in vessel remodeling and its regulatory mechanism during developmental angiogenesis. Cell Mol Life Sci 2023; 80:162. [PMID: 37221410 PMCID: PMC11072276 DOI: 10.1007/s00018-023-04801-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 04/06/2023] [Accepted: 05/06/2023] [Indexed: 05/25/2023]
Abstract
Vessel remodeling is essential for a functional and mature vascular network. According to the difference in endothelial cell (EC) behavior, we classified vessel remodeling into vessel pruning, vessel regression and vessel fusion. Vessel remodeling has been proven in various organs and species, such as the brain vasculature, subintestinal veins (SIVs), and caudal vein (CV) in zebrafish and yolk sac vessels, retina, and hyaloid vessels in mice. ECs and periendothelial cells (such as pericytes and astrocytes) contribute to vessel remodeling. EC junction remodeling and actin cytoskeleton dynamic rearrangement are indispensable for vessel pruning. More importantly, blood flow has a vital role in vessel remodeling. In recent studies, several mechanosensors, such as integrins, platelet endothelial cell adhesion molecule-1 (PECAM-1)/vascular endothelial cell (VE-cadherin)/vascular endothelial growth factor receptor 2 (VEGFR2) complex, and notch1, have been shown to contribute to mechanotransduction and vessel remodeling. In this review, we highlight the current knowledge of vessel remodeling in mouse and zebrafish models. We further underline the contribution of cellular behavior and periendothelial cells to vessel remodeling. Finally, we discuss the mechanosensory complex in ECs and the molecular mechanisms responsible for vessel remodeling.
Collapse
Affiliation(s)
- Lin Wen
- Key Laboratory for Biorheological Science and Technology of Ministry of Education, State and Local Joint Engineering Laboratory for Vascular Implants, Bioengineering College of Chongqing University, Chongqing, 400030, China
| | - Wenhua Yan
- Key Laboratory for Biorheological Science and Technology of Ministry of Education, State and Local Joint Engineering Laboratory for Vascular Implants, Bioengineering College of Chongqing University, Chongqing, 400030, China
| | - Li Zhu
- Cyrus Tang Hematology Center, Cyrus Tang Medical Institute, Collaborative Innovation Center of Hematology of Jiangsu Province, Soochow University, Suzhou, 215123, China
| | - Chaojun Tang
- Cyrus Tang Hematology Center, Cyrus Tang Medical Institute, Collaborative Innovation Center of Hematology of Jiangsu Province, Soochow University, Suzhou, 215123, China.
| | - Guixue Wang
- Key Laboratory for Biorheological Science and Technology of Ministry of Education, State and Local Joint Engineering Laboratory for Vascular Implants, Bioengineering College of Chongqing University, Chongqing, 400030, China.
- JinFeng Laboratory, Chongqing, 401329, China.
| |
Collapse
|
2
|
Díaz-Flores L, Gutiérrez R, García MP, González-Gómez M, Díaz-Flores L, Carrasco JL, Madrid JF, Rodríguez Bello A. Comparison of the Behavior of Perivascular Cells (Pericytes and CD34+ Stromal Cell/Telocytes) in Sprouting and Intussusceptive Angiogenesis. Int J Mol Sci 2022; 23:ijms23169010. [PMID: 36012273 PMCID: PMC9409369 DOI: 10.3390/ijms23169010] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 08/09/2022] [Accepted: 08/10/2022] [Indexed: 11/16/2022] Open
Abstract
Perivascular cells in the pericytic microvasculature, pericytes and CD34+ stromal cells/telocytes (CD34+SCs/TCs), have an important role in angiogenesis. We compare the behavior of these cells depending on whether the growth of endothelial cells (ECs) from the pre-existing microvasculature is toward the interstitium with vascular bud and neovessel formation (sprouting angiogenesis) or toward the vascular lumen with intravascular pillar development and vessel division (intussusceptive angiogenesis). Detachment from the vascular wall, mobilization, proliferation, recruitment, and differentiation of pericytes and CD34+SCs/TCs, as well as associated changes in vessel permeability and functionality, and modifications of the extracellular matrix are more intense, longer lasting over time, and with a greater energy cost in sprouting angiogenesis than in intussusceptive angiogenesis, in which some of the aforementioned events do not occur or are compensated for by others (e.g., sparse EC and pericyte proliferation by cell elongation and thinning). The governing mechanisms involve cell-cell contacts (e.g., peg-and-socket junctions between pericytes and ECs), multiple autocrine and paracrine signaling molecules and pathways (e.g., vascular endothelial growth factor, platelet-derived growth factor, angiopoietins, transforming growth factor B, ephrins, semaphorins, and metalloproteinases), and other factors (e.g., hypoxia, vascular patency, and blood flow). Pericytes participate in vessel development, stabilization, maturation and regression in sprouting angiogenesis, and in interstitial tissue structure formation of the pillar core in intussusceptive angiogenesis. In sprouting angiogenesis, proliferating perivascular CD34+SCs/TCs are an important source of stromal cells during repair through granulation tissue formation and of cancer-associated fibroblasts (CAFs) in tumors. Conversely, CD34+SCs/TCs have less participation as precursor cells in intussusceptive angiogenesis. The dysfunction of these mechanisms is involved in several diseases, including neoplasms, with therapeutic implications.
Collapse
Affiliation(s)
- Lucio Díaz-Flores
- Department of Basic Medical Sciences, Faculty of Medicine, University of La Laguna, 38071 Tenerife, Spain
- Correspondence: ; Tel.: +34-922-319317; Fax: +34-922-319279
| | - Ricardo Gutiérrez
- Department of Basic Medical Sciences, Faculty of Medicine, University of La Laguna, 38071 Tenerife, Spain
| | - Maria Pino García
- Department of Pathology, Eurofins Megalab–Hospiten Hospitals, 38100 Tenerife, Spain
| | - Miriam González-Gómez
- Department of Basic Medical Sciences, Faculty of Medicine, University of La Laguna, 38071 Tenerife, Spain
- Instituto de Tecnologías Biomédicas de Canarias, University of La Laguna, 38071 Tenerife, Spain
| | - Lucio Díaz-Flores
- Department of Basic Medical Sciences, Faculty of Medicine, University of La Laguna, 38071 Tenerife, Spain
| | - Jose Luis Carrasco
- Department of Basic Medical Sciences, Faculty of Medicine, University of La Laguna, 38071 Tenerife, Spain
| | - Juan Francisco Madrid
- Department of Cell Biology and Histology, School of Medicine, Campus of International Excellence “Campus Mare Nostrum”, IMIB-Arrixaca, University of Murcia, 30120 Murcia, Spain
| | - Aixa Rodríguez Bello
- Department of Bioquímica, Microbiología, Biología Celular y Genética, University of La Laguna, 38071 Tenerife, Spain
| |
Collapse
|
3
|
Ke FS, Holloway S, Uren RT, Wong AW, Little MH, Kluck RM, Voss AK, Strasser A. The BCL-2 family member BID plays a role during embryonic development in addition to its BH3-only protein function by acting in parallel to BAX, BAK and BOK. EMBO J 2022; 41:e110300. [PMID: 35758142 PMCID: PMC9340487 DOI: 10.15252/embj.2021110300] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 05/27/2022] [Accepted: 05/30/2022] [Indexed: 12/31/2022] Open
Abstract
The intrinsic apoptosis pathway, regulated by the BCL-2 protein family, is essential for embryonic development. Using mice lacking all known apoptosis effectors, BAX, BAK and BOK, we have previously defined the processes during development that require apoptosis. Rare Bok-/- Bax-/- Bak-/- triple knockout (TKO) mice developed to adulthood and several tissues that were thought to require apoptosis during development appeared normal. This raises the question if all apoptosis had been abolished in the TKO mice or if other BCL-2 family members could act as effectors of apoptosis. Here, we investigated the role of BID, generally considered to link the extrinsic and intrinsic apoptosis pathways, acting as a BH3-only protein initiating apoptosis upstream of BAX and BAK. We found that Bok-/- Bax-/- Bak-/- Bid-/- quadruple knockout (QKO) mice have additional developmental anomalies compared to TKO mice, consistent with a role of BID, not only upstream but also in parallel to BAX, BAK and BOK. Mitochondrial experiments identified a small cytochrome c-releasing activity of full-length BID. Collectively, these findings suggest a new effector role for BID in the intrinsic apoptosis pathway.
Collapse
Affiliation(s)
- Francine S Ke
- The Walter and Eliza Hall Institute of Medical Research (WEHI)MelbourneVicAustralia,Department of Medical BiologyUniversity of MelbourneMelbourneVicAustralia
| | - Steven Holloway
- The Walter and Eliza Hall Institute of Medical Research (WEHI)MelbourneVicAustralia
| | - Rachel T Uren
- The Walter and Eliza Hall Institute of Medical Research (WEHI)MelbourneVicAustralia,Department of Medical BiologyUniversity of MelbourneMelbourneVicAustralia
| | - Agnes W Wong
- The Walter and Eliza Hall Institute of Medical Research (WEHI)MelbourneVicAustralia
| | - Melissa H Little
- Department of PaediatricsUniversity of MelbourneMelbourneVicAustralia,Murdoch Children's Medical Research InstituteMelbourneVicAustralia
| | - Ruth M Kluck
- The Walter and Eliza Hall Institute of Medical Research (WEHI)MelbourneVicAustralia,Department of Medical BiologyUniversity of MelbourneMelbourneVicAustralia
| | - Anne K Voss
- The Walter and Eliza Hall Institute of Medical Research (WEHI)MelbourneVicAustralia,Department of Medical BiologyUniversity of MelbourneMelbourneVicAustralia
| | - Andreas Strasser
- The Walter and Eliza Hall Institute of Medical Research (WEHI)MelbourneVicAustralia,Department of Medical BiologyUniversity of MelbourneMelbourneVicAustralia
| |
Collapse
|
4
|
Tisch N, Ruiz de Almodóvar C. Contribution of cell death signaling to blood vessel formation. Cell Mol Life Sci 2021; 78:3247-3264. [PMID: 33783563 PMCID: PMC8038986 DOI: 10.1007/s00018-020-03738-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 12/06/2020] [Accepted: 12/08/2020] [Indexed: 02/07/2023]
Abstract
The formation of new blood vessels is driven by proliferation of endothelial cells (ECs), elongation of maturing vessel sprouts and ultimately vessel remodeling to create a hierarchically structured vascular system. Vessel regression is an essential process to remove redundant vessel branches in order to adapt the final vessel density to the demands of the surrounding tissue. How exactly vessel regression occurs and whether and to which extent cell death contributes to this process has been in the focus of several studies within the last decade. On top, recent findings challenge our simplistic view of the cell death signaling machinery as a sole executer of cellular demise, as emerging evidences suggest that some of the classic cell death regulators even promote blood vessel formation. This review summarizes our current knowledge on the role of the cell death signaling machinery with a focus on the apoptosis and necroptosis signaling pathways during blood vessel formation in development and pathology.
Collapse
Affiliation(s)
- Nathalie Tisch
- Department of Vascular Dysfunction, European Center for Angioscience (ECAS), Faculty of Medicine Mannheim, University of Heidelberg, Mannheim, Germany
| | - Carmen Ruiz de Almodóvar
- Department of Vascular Dysfunction, European Center for Angioscience (ECAS), Faculty of Medicine Mannheim, University of Heidelberg, Mannheim, Germany.
| |
Collapse
|
5
|
Egbu E. The Outcome of Manual Small Incision Cataract Surgery and Anterior Vitrectomy for Persistent Fetal Vasculature in an 18-Year-Old Woman: A One-Year Follow-Up. Cureus 2020; 12:e10605. [PMID: 33123424 PMCID: PMC7584328 DOI: 10.7759/cureus.10605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
The surgical management of persistent fetal vasculature (PFV) is challenging and the visual outcome can be compromised by coexisting ocular pathologies and amblyopia. It can be considered for relief of retinal traction and improved cosmetic appeal when a squint or a posterior capsular cataract is present. In the case presented in this report, the intermittent exotropia improved from 45 to 30 degrees in one year, which suggests an improvement in binocular single vision. There was also a resolution of the leukocoria and retinal traction. The patient underwent the following examinations: visual activity, slit-lamp biomicroscopy, intraocular pressure (Goldmann), fundus photography (OCT TOPCON, 3D OCT-1 Maestro, Topcon, Tokyo, Japan), B-scan Doppler ultrasonography (Mindray DC-N3, Mindray, Shenzhen, China), Keratometry (Topcon KR 800, Topcon, Tokyo, Japan), and axial length (Sonomed 300AP+A Scan/Pachymeter, Sonomed Escalon, Lake Success, NY). Intraocular lens (IOL) power was calculated with the Sanders-Retzlaff-Kraff (SRK) II formula. During surgery, a rigid polymethyl methacrylate (PMMA) IOL was inserted into the sulcus after excision of the lesion and anterior vitrectomy. The first day's postoperative evaluation included visual acuity, corneal transparency, depth of anterior chamber, pupil size, shape, pupillary reaction to light, and position of the IOL. Intraocular pressure was normal within the follow-up period. Fundus photography and B-scan examinations were performed at one month and one year.
Collapse
Affiliation(s)
- Ejike Egbu
- Ophthalmology, Lily Hospitals Limited, Warri, NGA
| |
Collapse
|
6
|
Iwanaga T, Nio-Kobayashi J, Takahashi-Iwanaga H. Bush-like integrin filament networks associated with hyaloid vasculature in murine neonate eyes. Biomed Res 2019; 40:79-85. [PMID: 30982803 DOI: 10.2220/biomedres.40.79] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The vitreous of perinatal mice temporarily develops a unique vascular system, called the vasa hyaloidea propria (VHP). Observations showed the vessels possessed an extracellular matrix including the basement membrane in their entire length. Immunostaining of whole mount preparations of VHP with integrin β1 antibody displayed a bush-like network consisting of long and straight fibers which were associated with the VHP but extended apart from the blood vessels. Electron microscopically, each fiber was composed of a bundle of thin filaments different from collagen fibrils. Macrophages associated with the VHP appeared to be arrested by the integrin bushes. The integrin bushes fragmented and disappeared by postnatal day 10, just before the regression of the VHP. Macrophages were involved in the digestion and clearance of integrin bushes. The vitreous integrin bushes appear to provide a scaffold for architectural maintenance of the hyaloid vessels and macrophages.
Collapse
Affiliation(s)
- Toshihiko Iwanaga
- Laboratory of Histology and Cytology, Department of Anatomy, Hokkaido University Graduate School of Medicine
| | - Junko Nio-Kobayashi
- Laboratory of Histology and Cytology, Department of Anatomy, Hokkaido University Graduate School of Medicine
| | - Hiromi Takahashi-Iwanaga
- Laboratory of Histology and Cytology, Department of Anatomy, Hokkaido University Graduate School of Medicine
| |
Collapse
|
7
|
Kishimoto A, Kimura S, Nio-Kobayashi J, Takahashi-Iwanaga H, Park AM, Iwanaga T. Histochemical characteristics of regressing vessels in the hyaloid vascular system of neonatal mice: Novel implication for vascular atrophy. Exp Eye Res 2018; 172:1-9. [PMID: 29596849 DOI: 10.1016/j.exer.2018.03.024] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Revised: 03/07/2018] [Accepted: 03/23/2018] [Indexed: 12/29/2022]
Abstract
The hyaloid vasculature constitutes a transitory system nourishing the internal structures of the developing eye, but the mechanism of vascular regression and its cell biological characteristics are not fully understood. The present study aimed to reveal the specificity of the hyaloid vessels by a systematic immunohistochemical approach for marker substances of myeloid cells and the extracellular matrix (ECM) in neonatal mice. Macrophages immunoreactive for F4/80, cathepsin D, and LYVE-1 gathered around the vasa hyaloidea propria (VHP), while small round cells in vascular lumen of VHP were selectively immunoreactive for galectin-3; their segmented nuclei and immunoreactivities for Ly-6G, CD11b, and myeloperoxidase indicated their neutrophilic origin. VHP possessed thick ECM and a dense pericyte envelope as demonstrated by immunostaining for laminin, type IV collagen, integrin β1, and NG2. The galectin-3+ cells loosely aggregated with numerous erythrocytes in the lumen of hyaloid vessels in a manner reminiscent of vascular congestion. Galectin-3 is known to polymerize and form a complex with ECM and NG2 as well as recruit leukocytes on the endothelium. Observation of galectin-3 KO mice implicated the involvement of galectin-3 in the regression of hyaloid vasculature. Since macrophages may play central roles including blocking of the blood flow and the induction of apoptosis in the regression, galectin-3+ neutrophils may play a supportive role in the macrophage-mediated involution of the hyaloid vascular system.
Collapse
Affiliation(s)
- Ayuko Kishimoto
- Laboratory of Histology and Cytology, Department of Anatomy, Hokkaido University Graduate School of Medicine, Sapporo 060-8638, Japan
| | - Shunsuke Kimura
- Laboratory of Histology and Cytology, Department of Anatomy, Hokkaido University Graduate School of Medicine, Sapporo 060-8638, Japan
| | - Junko Nio-Kobayashi
- Laboratory of Histology and Cytology, Department of Anatomy, Hokkaido University Graduate School of Medicine, Sapporo 060-8638, Japan
| | - Hiromi Takahashi-Iwanaga
- Laboratory of Histology and Cytology, Department of Anatomy, Hokkaido University Graduate School of Medicine, Sapporo 060-8638, Japan
| | - Ah-Mee Park
- Department of Microbiology, Kindai University Faculty of Medicine, Osaka 589-8511, Japan
| | - Toshihiko Iwanaga
- Laboratory of Histology and Cytology, Department of Anatomy, Hokkaido University Graduate School of Medicine, Sapporo 060-8638, Japan.
| |
Collapse
|
8
|
Abstract
The eye is susceptible to adverse toxic effects by direct application, inadvertent ocular contact, or systemic exposure to chemicals or their metabolites. Although the albino rat is a less than ideal model for ocular toxicity studies, it has gained popularity for specific applications and may be the first species in which the ocular toxicity of a systemically administered xenobiotic becomes evident. This chapter reviews the embryology, anatomy, and physiology of the eye and associated glands and describes common nonneoplastic and neoplastic lesions encountered in laboratory rats.
Collapse
|
9
|
Wang S, Zaitoun IS, Johnson RP, Jamali N, Gurel Z, Wintheiser CM, Strasser A, Lindner V, Sheibani N, Sorenson CM. Bim expression in endothelial cells and pericytes is essential for regression of the fetal ocular vasculature. PLoS One 2017; 12:e0178198. [PMID: 28552963 PMCID: PMC5446173 DOI: 10.1371/journal.pone.0178198] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Accepted: 05/08/2017] [Indexed: 12/03/2022] Open
Abstract
Apoptosis plays a central role in developmental and pathological angiogenesis and vessel regression. Bim is a pro-apoptotic Bcl-2 family member that plays a prominent role in both developmental and pathological ocular vessel regression, and neovascularization. Endothelial cells (EC) and pericytes (PC) each play unique roles during vascular development, maintenance and regression. We recently showed that germline deletion of Bim results in persistent hyaloid vasculature, increased retinal vascular density and prevents retinal vessel regression in response to hyperoxia. To determine whether retinal vascular regression is attributable to Bim expression in EC or PC we generated mice carrying a conditional Bim allele (BimFlox/Flox) and VE-cadherin-cre (BimEC mice) or Pdgfrb-cre (BimPC mice). BimEC and BimPC mice demonstrated attenuated hyaloid vessel regression and postnatal retinal vascular remodeling. We also observed decreased retinal vascular apoptosis and proliferation. Unlike global Bim -/- mice, mice conditionally lacking Bim in EC or PC underwent hyperoxia-mediated vessel obliteration and subsequent retinal neovascularization during oxygen-induced ischemic retinopathy similar to control littermates. Thus, understanding the cell autonomous role Bim plays in the retinal vascular homeostasis will give us new insight into how to modulate pathological retinal neovascularization and vessel regression to preserve vision.
Collapse
Affiliation(s)
- Shoujian Wang
- Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
| | - Ismail S. Zaitoun
- Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
| | - Ryan P. Johnson
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
| | - Nasim Jamali
- Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
- McPherson Eye Research Institute, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
| | - Zafer Gurel
- Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
| | - Catherine M. Wintheiser
- Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
| | - Andreas Strasser
- The Walter and Eliza Hall Institute of Medical Research, University of Melbourne, Melbourne, Victoria, Australia
- Department of Medical Biology, University of Melbourne, Melbourne, Victoria, Australia
| | - Volkhard Lindner
- Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, Maine, United States of America
| | - Nader Sheibani
- Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
- McPherson Eye Research Institute, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
| | - Christine M. Sorenson
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
- McPherson Eye Research Institute, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
- * E-mail:
| |
Collapse
|
10
|
Kishimoto A, Takahashi-Iwanaga H, Watanabe M M, Iwanaga T. Differential expression of endothelial nutrient transporters (MCT1 and GLUT1) in the developing eyes of mice. Exp Eye Res 2016; 153:170-177. [PMID: 27793618 DOI: 10.1016/j.exer.2016.10.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 10/05/2016] [Accepted: 10/24/2016] [Indexed: 12/31/2022]
Abstract
The blood-brain barrier in the neonatal brain expresses the monocarboxylate transporter (MCT)-1 rather than the glucose transporter (GLUT)-1, due to the special energy supply during the suckling period. The hyaloid vascular system, consisting of the vasa hyaloidea propria and tunica vasculosa lentis, is a temporary vasculature present only during the early development of mammalian eyes and later regresses. Although the ocular vasculature manifests such a unique developmental process, no information is available concerning the expression of endothelial nutrient transporters in the developing eye. The present immunohistochemical study using whole mount preparations of murine eyes found that the hyaloid vascular system predominantly expressed GLUT1 in the endothelium, in contrast to the brain endothelium. Characteristically, the endothelium in peripheral regions of the neonatal hyaloid vessels displayed a mosaic pattern of MCT1-immunoreactive cells scattered within the GLUT1-expressing endothelium. The proper retinal vessels first developed by sprouting angiogenesis endowed with filopodia, which were absolutely free from the immunoreactivities of GLUT1 and MCT1. The remodeling retinal capillary networks and veins in the surface layer of the retina mainly expressed MCT1 until the weaning period. Immunostaining of MCT1 in the retina revealed fine radicular processes projecting from the endothelium, differing from the MCT1-immunonegative filopodia. These findings suggest that the expression of nutrient transporters in the ocular blood vessels is differentially regulated at a cellular level and that the neonatal eyes provide an interesting model for research on nutrient transporters in the endothelium.
Collapse
Affiliation(s)
- Ayuko Kishimoto
- Laboratory of Histology and Cytology, Department of Anatomy, Hokkaido University, Graduate School of Medicine, Sapporo 060-8638, Japan
| | - Hiromi Takahashi-Iwanaga
- Laboratory of Histology and Cytology, Department of Anatomy, Hokkaido University, Graduate School of Medicine, Sapporo 060-8638, Japan
| | - Masahiko Watanabe M
- Laboratory of Histology and Cytology, Department of Anatomy, Hokkaido University, Graduate School of Medicine, Sapporo 060-8638, Japan
| | - Toshihiko Iwanaga
- Laboratory of Histology and Cytology, Department of Anatomy, Hokkaido University, Graduate School of Medicine, Sapporo 060-8638, Japan.
| |
Collapse
|
11
|
Mechanisms of Vessel Pruning and Regression. Dev Cell 2015; 34:5-17. [PMID: 26151903 DOI: 10.1016/j.devcel.2015.06.004] [Citation(s) in RCA: 188] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Revised: 05/26/2015] [Accepted: 06/03/2015] [Indexed: 01/27/2023]
Abstract
The field of angiogenesis research has primarily focused on the mechanisms of sprouting angiogenesis. Yet vascular networks formed by vessel sprouting subsequently undergo extensive vascular remodeling to form a functional and mature vasculature. This "trimming" includes distinct processes of vascular pruning, the regression of selected vascular branches. In some situations complete vascular networks may undergo physiological regression. Vessel regression is an understudied yet emerging field of research. This review summarizes the state-of-the-art of vessel pruning and regression with a focus on the cellular processes and the molecular regulators of vessel maintenance and regression.
Collapse
|
12
|
Schäker K, Bartsch S, Patry C, Stoll SJ, Hillebrands JL, Wieland T, Kroll J. The bipartite rac1 Guanine nucleotide exchange factor engulfment and cell motility 1/dedicator of cytokinesis 180 (elmo1/dock180) protects endothelial cells from apoptosis in blood vessel development. J Biol Chem 2015; 290:6408-18. [PMID: 25586182 DOI: 10.1074/jbc.m114.633701] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Engulfment and cell motility 1/dedicator of cytokinesis 180 (Elmo1/Dock180) is a bipartite guanine nucleotide exchange factor for the monomeric GTPase Ras-related C3 botulinum toxin substrate 1 (Rac1). Elmo1/Dock180 regulates Rac1 activity in a specific spatiotemporal manner in endothelial cells (ECs) during zebrafish development and acts downstream of the Netrin-1/Unc5-homolog B (Unc5B) signaling cascade. However, mechanistic details on the pathways by which Elmo1/Dock180 regulates endothelial function and vascular development remained elusive. In this study, we aimed to analyze the vascular function of Elmo1 and Dock180 in human ECs and during vascular development in zebrafish embryos. In vitro overexpression of Elmo1 and Dock180 in ECs reduced caspase-3/7 activity and annexin V-positive cell number upon induction of apoptosis. This protective effect of Elmo1 and Dock180 is mediated by activation of Rac1, p21-activated kinase (PAK) and AKT/protein kinase B (AKT) signaling. In zebrafish, Elmo1 and Dock180 overexpression reduced the total apoptotic cell and apoptotic EC number and promoted the formation of blood vessels during embryogenesis. In conclusion, Elmo1 and Dock180 protect ECs from apoptosis by the activation of the Rac1/PAK/AKT signaling cascade in vitro and in vivo. Thus, Elmo1 and Dock180 facilitate blood vessel formation by stabilization of the endothelium during angiogenesis.
Collapse
Affiliation(s)
- Kathrin Schäker
- From the Department of Vascular Biology and Tumor Angiogenesis, Center for Biomedicine and Medical Technology Mannheim (CBTM) and Division of Vascular Oncology and Metastasis, German Cancer Research Center (DKFZ-ZMBH Alliance), 69120 Heidelberg, Germany, and
| | - Susanne Bartsch
- From the Department of Vascular Biology and Tumor Angiogenesis, Center for Biomedicine and Medical Technology Mannheim (CBTM) and
| | - Christian Patry
- From the Department of Vascular Biology and Tumor Angiogenesis, Center for Biomedicine and Medical Technology Mannheim (CBTM) and
| | - Sandra J Stoll
- From the Department of Vascular Biology and Tumor Angiogenesis, Center for Biomedicine and Medical Technology Mannheim (CBTM) and
| | - Jan-Luuk Hillebrands
- Department of Pathology and Medical Biology, Division of Pathology, University Medical Center Groningen, 9700 RB Groningen, The Netherlands
| | - Thomas Wieland
- Institute of Experimental and Clinical Pharmacology and Toxicology, Medical Faculty Mannheim of Heidelberg University, 68167 Mannheim, Germany
| | - Jens Kroll
- From the Department of Vascular Biology and Tumor Angiogenesis, Center for Biomedicine and Medical Technology Mannheim (CBTM) and Division of Vascular Oncology and Metastasis, German Cancer Research Center (DKFZ-ZMBH Alliance), 69120 Heidelberg, Germany, and
| |
Collapse
|
13
|
Sarnat HB, Resch L, Flores-Sarnat L, Yu W. Precocious synapses in 13.5-week fetal holoprosencephalic cortex and cyclopean retina. Brain Dev 2014; 36:463-71. [PMID: 24529974 DOI: 10.1016/j.braindev.2014.01.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Revised: 01/10/2014] [Accepted: 01/11/2014] [Indexed: 11/29/2022]
Abstract
BACKGROUND Genetic programming of cerebral development involves tissue morphogenesis and also timing of developmental processes. Precocious synaptogenesis in the neocortical plate was previously demonstrated in 5 of 6 fetuses of 20-31 weeks gestation. MATERIALS AND METHODS Neuropathological examination was performed of a 13-week-5-day fetus with trisomy-13, a lobar holoprosencephaly, hydrocephalus, cyclopia and absence of ears. Immunocytochemical demonstration of the synaptic vesicle protein synaptophysin was performed in the brain and retina, along with other neuronal markers. RESULTS Synaptophysin reactivity in the cortical plate was patchy and precocious. Radial glial fibres, demonstrated by vimentin, were oriented parallel to the cortical plate rather than perpendicular, probably because of hydrocephalus. A corpus striatum was not identified, but the poorly formed thalamus exhibited synaptophysin reactivity around many neurones. The cyclopean eye had ocular features of maturational delay including persistent hyaloid artery; ganglion cells were reduced in number, but retinal synaptophysin reactivity was paradoxically precocious. CONCLUSIONS Holoprosencephaly exhibits abnormal patchy synapse distribution in the neocortex and retina; synaptogenesis was precocious, as we previously described in older fetuses. Too soon an onset of synapse formation may promote early epileptic circuitry, leading to severe infantile epilepsies postnatally. The visual system is the last of the special sensory systems to mature, yet in this case showed too early synapse formation. In HPE, cyclopia and in trisomy 13, total absence of external ears has not been reported; it results from faulty craniofacial induction by neural crest.
Collapse
Affiliation(s)
- Harvey B Sarnat
- Department of Paediatrics, University of Calgary Faculty of Medicine and Alberta Children's Hospital Research Institute, Calgary, Alberta, Canada; Department of Pathology (Neuropathology), University of Calgary Faculty of Medicine and Alberta Children's Hospital Research Institute, Calgary, Alberta, Canada; Department of Clinical Neurosciences, University of Calgary Faculty of Medicine and Alberta Children's Hospital Research Institute, Calgary, Alberta, Canada.
| | - Lothar Resch
- Department of Pathology (Neuropathology), University of Calgary Faculty of Medicine and Alberta Children's Hospital Research Institute, Calgary, Alberta, Canada
| | - Laura Flores-Sarnat
- Department of Paediatrics, University of Calgary Faculty of Medicine and Alberta Children's Hospital Research Institute, Calgary, Alberta, Canada; Department of Clinical Neurosciences, University of Calgary Faculty of Medicine and Alberta Children's Hospital Research Institute, Calgary, Alberta, Canada
| | - Weiming Yu
- Department of Pathology (Paediatric), University of Calgary Faculty of Medicine and Alberta Children's Hospital Research Institute, Calgary, Alberta, Canada
| |
Collapse
|
14
|
Kochhan E, Lenard A, Ellertsdottir E, Herwig L, Affolter M, Belting HG, Siekmann AF. Blood flow changes coincide with cellular rearrangements during blood vessel pruning in zebrafish embryos. PLoS One 2013; 8:e75060. [PMID: 24146748 PMCID: PMC3795766 DOI: 10.1371/journal.pone.0075060] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Accepted: 08/08/2013] [Indexed: 12/26/2022] Open
Abstract
After the initial formation of a highly branched vascular plexus, blood vessel pruning generates a hierarchically structured network with improved flow characteristics. We report here on the cellular events that occur during the pruning of a defined blood vessel in the eye of developing zebrafish embryos. Time-lapse imaging reveals that the connection of a new blood vessel sprout with a previously perfused multicellular endothelial tube leads to the formation of a branched, Y-shaped structure. Subsequently, endothelial cells in parts of the previously perfused branch rearrange from a multicellular into a unicellular tube, followed by blood vessel detachment. This process is accompanied by endothelial cell death. Finally, we show that differences in blood flow between neighboring vessels are important for the completion of the pruning process. Our data suggest that flow induced changes in tubular architecture ensure proper blood vessel pruning.
Collapse
Affiliation(s)
- Eva Kochhan
- Max Planck Institute for Molecular Biomedicine, Laboratory for Cardiovascular Patterning, Muenster, Germany
| | - Anna Lenard
- Biozentrum der Universität Basel, Abteilung Zellbiologie, Basel, Switzerland
| | - Elin Ellertsdottir
- Biozentrum der Universität Basel, Abteilung Zellbiologie, Basel, Switzerland
| | - Lukas Herwig
- Biozentrum der Universität Basel, Abteilung Zellbiologie, Basel, Switzerland
| | - Markus Affolter
- Biozentrum der Universität Basel, Abteilung Zellbiologie, Basel, Switzerland
| | - Heinz-Georg Belting
- Biozentrum der Universität Basel, Abteilung Zellbiologie, Basel, Switzerland
| | - Arndt F. Siekmann
- Max Planck Institute for Molecular Biomedicine, Laboratory for Cardiovascular Patterning, Muenster, Germany
- * E-mail:
| |
Collapse
|
15
|
A developmental defect in astrocytes inhibits programmed regression of the hyaloid vasculature in the mammalian eye. Eur J Cell Biol 2011; 90:440-8. [PMID: 21354650 DOI: 10.1016/j.ejcb.2011.01.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2010] [Revised: 01/07/2011] [Accepted: 01/09/2011] [Indexed: 11/21/2022] Open
Abstract
Previously we reported the novel observation that astrocytes ensheath the persistent hyaloid artery, both in the Nuc1 spontaneous mutant rat, and in human PFV (persistent fetal vasculature) disease (Developmental Dynamics 234:36-47, 2005). We now show that astrocytes isolated from both the optic nerve and retina of Nuc1 rats migrate faster than wild type astrocytes. Aquaporin 4 (AQP4), the major water channel in astrocytes, has been shown to be important in astrocyte migration. We demonstrate that AQP4 expression is elevated in the astrocytes in PFV conditions, and we hypothesize that this causes the cells to migrate abnormally into the vitreous where they ensheath the hyaloid artery. This abnormal association of astrocytes with the hyaloid artery may impede the normal macrophage-mediated remodeling and regression of the hyaloid system.
Collapse
|
16
|
Floyd KA, Stella DR, Wang CC, Laurentz S, McCabe GP, Srivastava OP, Barnes S. Genistein and genistein-containing dietary supplements accelerate the early stages of cataractogenesis in the male ICR/f rat. Exp Eye Res 2010; 92:120-7. [PMID: 21147102 DOI: 10.1016/j.exer.2010.12.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2010] [Revised: 11/19/2010] [Accepted: 12/02/2010] [Indexed: 11/25/2022]
Abstract
Cataract-related loss of vision affects large numbers of people in today's aging populations and presents a healthcare burden to many nations. The role of dietary supplements within the lens is largely unknown, although benefits from dietary anti-oxidants are expected. In this study, the effects of genistein as its aglycone, a genistein-containing dietary supplement (Novasoy(®)200), and a genistein-containing food (soy protein isolate, PRO-FAM 932) on the development of lens opacity were examined in the hereditary cataractous ICR/f rat. These studies were carried out in a background diet of semi-purified, isoflavone-free AIN-76A with casein as its protein source. The amount of genistein for the experimental diets was standardized to its concentration (as genistein aglycone as well as simple and complex β-glucoside conjugates) in the soy protein isolate supplement. Also tested was a high-dose genistein diet containing an 11-fold higher amount of genistein aglycone. The composition of each diet was verified by reverse-phase HPLC and blood plasma isoflavone concentrations were determined by LC-tandem mass spectrometry. The development of opacity in each lens was monitored and digitally recorded using slit-lamp examination over the course of the study. Each of the genistein-containing diets caused a significantly more rapid development of fibrous opacification in the anterior cortical region and development of apparent water clefts or vacuoles in the posterior subcapsular region than the AIN-76A control diet; however, the establishment of dense lens opacification was not significantly different between each of the diets. There was also no significant difference observed between the low-dose and high-dose genistein aglycone groups. These data suggest that genistein-containing dietary supplements accelerate the early stages of cataractogenesis in the male ICR/f rat, with no dose-dependent effects.
Collapse
Affiliation(s)
- Kyle A Floyd
- Department of Pharmacology and Toxicology, University of Alabama at Birmingham, L108 Volker Hall, 1670 University Blvd., Birmingham, AL 35294, USA
| | | | | | | | | | | | | |
Collapse
|
17
|
Arroyo AG, Iruela-Arispe ML. Extracellular matrix, inflammation, and the angiogenic response. Cardiovasc Res 2010; 86:226-35. [PMID: 20154066 DOI: 10.1093/cvr/cvq049] [Citation(s) in RCA: 215] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Inflammation and angiogenesis are frequently coupled in pathological situations such as atherosclerosis, diabetes, and arthritis. The inflammatory response increases capillary permeability and induces endothelial activation, which, when persistent, results in capillary sprouting. This inflammation-induced angiogenesis and the subsequent remodelling steps are in large part mediated by extracellular matrix (ECM) proteins and proteases. The focal increase in capillary permeability is an early consequence of inflammation, and results in the deposition of a provisional fibrin matrix. Subsequently, ECM turnover by proteases permits an invasive program by specialized endothelial cells whose phenotype can be regulated by inflammatory stimuli. ECM activity also provides specific mechanical forces, exposes cryptic adhesion sites, and releases biologically active fragments (matrikines) and matrix-sequestered growth factors, all of which are critical for vascular morphogenesis. Further matrix remodelling and vascular regression contribute to the resolution of the inflammatory response and facilitate tissue repair.
Collapse
Affiliation(s)
- Alicia G Arroyo
- Department of Vascular Biology and Inflammation, Centro Nacional de Investigaciones Cardiovasculares, Melchor Fernández Almagro 3, Madrid 28029, Spain.
| | | |
Collapse
|
18
|
Nishitani K, Sasaki K. Macrophage localization in the developing lens primordium of the mouse embryo – An immunohistochemical study. Exp Eye Res 2006; 83:223-8. [PMID: 16549063 DOI: 10.1016/j.exer.2005.12.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2005] [Revised: 11/09/2005] [Accepted: 12/07/2005] [Indexed: 11/20/2022]
Abstract
In mammals, macrophages are known to play an important role in lens development. Macrophages in the embryonic lens are positive for F4/80 monoclonal antibody, and, from 10.5 days to 12 days of gestation, numerous macrophages were observed in the ectoderm, lens vesicle, lens cavity and surrounding mesenchymal tissue, phagocytosing and removing degenerating epithelial cells. During primary lens fiber differentiation, the narrowing lens cavity contained numerous macrophages. Most of the macrophages in the cavity attached to the anterior epithelial wall of the lens vesicle, but a few macrophages were found within the lens epithelial cell layer. Conversely, the thickening posterior wall of the vesicle did not contain any positive cells. After the lens cavity was filled, intralental positive cells disappeared. These characteristic localizations of macrophages in the developing lens to remove apoptotic dead cells may indicate that cell death took place mainly in the anterior wall of the lens vesicle, that is, in the lens epithelium.
Collapse
Affiliation(s)
- Koji Nishitani
- Department of Anatomy, Kawasaki Medical School, 577 Matsushima, Kurashiki 701-0192, Japan.
| | | |
Collapse
|
19
|
Baffert F, Le T, Sennino B, Thurston G, Kuo CJ, Hu-Lowe D, McDonald DM. Cellular changes in normal blood capillaries undergoing regression after inhibition of VEGF signaling. Am J Physiol Heart Circ Physiol 2005; 290:H547-59. [PMID: 16172161 DOI: 10.1152/ajpheart.00616.2005] [Citation(s) in RCA: 292] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The vasculature of the embryo requires vascular endothelial growth factor (VEGF) during development, but most adult blood vessels lose VEGF dependence. However, some capillaries in the respiratory tract and selected other organs of adult mice regress after VEGF inhibition. The present study sought to identify the sequence of events and the fate of endothelial cells, pericytes, and vascular basement membrane during capillary regression in mouse tracheas after VEGF signaling was blocked with a VEGF-receptor tyrosine kinase inhibitor AG-013736 or soluble receptor construct (VEGF Trap or soluble adenoviral VEGFR-1). Within 1 day, patency was lost and fibrin accumulated in some tracheal capillaries. Apoptotic endothelial cells marked by activated caspase-3 were present in capillaries without blood flow. VEGF inhibition was accompanied by a 19% decrease in tracheal capillaries over 7 days and 30% over 21 days. During this period, desmin/NG2-immunoreactive pericytes moved away from regressing capillaries onto surviving vessels. Empty sleeves of basement membrane, left behind by regressing endothelial cells, persisted for about 2 wk and served as a scaffold for vascular regrowth after treatment ended. The amount of regrowth was limited by the number of surviving basement membrane sleeves. These findings demonstrate that, after inhibition of VEGF signaling, some normal capillaries regress in a systematic sequence of events initiated by a cessation of blood flow and followed by apoptosis of endothelial cells, migration of pericytes away from regressing vessels, and formation of empty basement membrane sleeves that can facilitate capillary regrowth.
Collapse
Affiliation(s)
- Fabienne Baffert
- Cardiovascular Research Institute, and Dept. of Anatomy, Univ. of California, 513 Parnassus Ave., San Francisco, CA 94143-0452, USA
| | | | | | | | | | | | | |
Collapse
|
20
|
McKeller RN, Fowler JL, Cunningham JJ, Warner N, Smeyne RJ, Zindy F, Skapek SX. The Arf tumor suppressor gene promotes hyaloid vascular regression during mouse eye development. Proc Natl Acad Sci U S A 2002; 99:3848-53. [PMID: 11891301 PMCID: PMC122612 DOI: 10.1073/pnas.052484199] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
A key tumor suppressor mechanism that is disrupted frequently in human cancer involves the ARF and p53 genes. In mouse fibroblasts, the Arf gene product responds to abnormal mitogenic signals to activate p53 and trigger either cell cycle arrest or apoptosis. Recent evidence indicates that Arf also has p53-independent functions that may contribute to its tumor suppressor activity. Using Arf(-/-) and p53(-/-) mice, we have discovered a p53-independent requirement for Arf in the developmental regression of the hyaloid vascular system (HVS) in the mouse eye. Arf is expressed in the vitreous of the eye and is induced before HVS regression in the first postnatal week. In the absence of Arf, failed HVS regression causes a pathological process that resembles persistent hyperplastic primary vitreous, a developmental human eye disease thought to have a genetic basis. These findings demonstrate an essential and unexpected role for Arf during mouse eye development, provide insights into the potential genetic basis for persistent hyperplastic primary vitreous, and indicate that Arf regulates vascular regression in a p53-independent manner. The latter finding raises the possibility that Arf may function as a tumor suppressor at least in part by regulating tumor angiogenesis.
Collapse
Affiliation(s)
- Robyn N McKeller
- Department of Hematology/Oncology, Developmental Neurobiology, St. Jude Children's Research Hospital, 332 North Lauderdale Street, Memphis, TN 38105, USA
| | | | | | | | | | | | | |
Collapse
|
21
|
Morikawa S, Baluk P, Kaidoh T, Haskell A, Jain RK, McDonald DM. Abnormalities in pericytes on blood vessels and endothelial sprouts in tumors. THE AMERICAN JOURNAL OF PATHOLOGY 2002; 160:985-1000. [PMID: 11891196 PMCID: PMC1867175 DOI: 10.1016/s0002-9440(10)64920-6] [Citation(s) in RCA: 711] [Impact Index Per Article: 32.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 12/07/2001] [Indexed: 12/22/2022]
Abstract
Endothelial cells of tumor vessels have well-documented alterations, but it is less clear whether pericytes on these vessels are abnormal or even absent. Here we report that alpha-smooth muscle actin (alpha-SMA) and desmin-immunoreactive pericytes were present on >97% of blood vessels viewed by confocal microscopy in 100-microm-thick sections of three different spontaneous or implanted tumors in mice. However, the cells had multiple abnormalities. Unlike pericytes on capillaries in normal pancreatic islets, which had desmin but not alpha-SMA immunoreactivity, pericytes on capillary-size vessels in insulinomas in RIP-Tag2 transgenic mice expressed both desmin and alpha-SMA. Furthermore, pericytes in RIP-Tag2 tumors, as well as those in MCa-IV breast carcinomas and Lewis lung carcinomas, had an abnormally loose association with endothelial cells and extended cytoplasmic processes deep into the tumor tissue. alpha-SMA-positive pericytes also covered 73% of endothelial sprouts in RIP-Tag2 tumors and 92% of sprouts in the other tumors. Indeed, pericyte sleeves were significantly longer than the CD31-immunoreactive endothelial cell sprouts themselves in all three types of tumors. All three tumors also contained alpha-SMA-positive myofibroblasts that resembled pericytes but were not associated with blood vessels. We conclude that pericytes are present on most tumor vessels but have multiple abnormalities, including altered expression of marker proteins. In contrast to some previous studies, the almost ubiquitous presence of pericytes on tumor vessels found in the present study may be attributed to our use of both desmin and alpha-SMA as markers and 100-microm-thick tissue sections. The association of pericytes with endothelial sprouts raises the possibility of an involvement in sprout growth or retraction in tumors.
Collapse
Affiliation(s)
- Shunichi Morikawa
- Department of Anatomy and Cardiovascular Research Institute and Comprehensive Cancer Center, University of California, San Francisco, California 94143-0130, USA
| | | | | | | | | | | |
Collapse
|