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Seo YJ, Shim DB, Sharif A, Samson Z, Takechi R, Brown D. Circulatory disturbance of the cochlear spiral modiolar artery in a type 2 diabetic mouse model. Laryngoscope Investig Otolaryngol 2022; 7:1568-1574. [PMID: 36258860 PMCID: PMC9575088 DOI: 10.1002/lio2.917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 07/26/2022] [Accepted: 08/24/2022] [Indexed: 11/18/2022] Open
Abstract
Objective This study aimed to identify significant differences in cochlea microvessel size between a diabetic mouse model (db/db) and normal mice using three‐dimensional (3D) quantitative analysis. Methods Six control heterozygote db/+ as well as 18 male B6/BKS(D)‐Leprdb/J (db/db) mice aged 14 (n = 9) and 28 (n = 9) weeks were examined. After clearing the cochlea, we reconstructed the 3D volumes of the spiral modiolar artery (SMA) in the cochlea using light‐sheet microscopy and analyzed vessel wall thickness, cross‐sectional area, short and long diameter, and vessel height. Results The average SMA‐wall thickness in the db/db‐mouse group (3.418 ± 0.328 μm) was greater than that in the control group (2.388 ± 0.411 μm). The average cross‐sectional outer area, short diameter, and long diameter of the SMA in db/db mice were significantly larger than those in control mice (all p < 0.001). The cross‐sectional areas increased with age (control: 221.782 ± 121.230 μm, 14 weeks; 294.378 ± 151.008 μm, and 28 weeks; 312.925 ± 147.943 μm). Conclusion The db/db mice had thicker and larger proximal‐SMA vessel walls and diameters than control mice, respectively, thus potentially inducing increased blood viscosity or vascular insufficiency and aggravating hearing loss in type 2 diabetes mellitus. Level of Evidence IIb
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Affiliation(s)
- Young Joon Seo
- Department of Otorhinolaryngology Yonsei University Wonju College of Medicine Wonju South Korea
- Research Institute of Hearing Enhancement, Yonsei University Wonju College of Medicine Wonju South Korea
- Faculty of Health sciences Curtin University Bentley WA Australia
| | - Dae Bo Shim
- Department of Otorhinolaryngology Myongji Hospital, Hanyang University College of Medicine
| | - Arazu Sharif
- Curtin Health Innovation Research Institute, Curtin University Bentley WA Australia
| | - Zeke Samson
- Faculty of Health sciences Curtin University Bentley WA Australia
| | - Ryu Takechi
- Curtin Health Innovation Research Institute, Curtin University Bentley WA Australia
| | - Daniel Brown
- Faculty of Health sciences Curtin University Bentley WA Australia
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2
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Zhang J, Hou Z, Wang X, Jiang H, Neng L, Zhang Y, Yu Q, Burwood G, Song J, Auer M, Fridberger A, Hoa M, Shi X. VEGFA165 gene therapy ameliorates blood-labyrinth barrier breakdown and hearing loss. JCI Insight 2021; 6:143285. [PMID: 33690221 PMCID: PMC8119217 DOI: 10.1172/jci.insight.143285] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 03/05/2021] [Indexed: 12/20/2022] Open
Abstract
Millions of people are affected by hearing loss. Hearing loss is frequently caused by noise or aging and often associated with loss of pericytes. Pericytes populate the small vessels in the adult cochlea. However, their role in different types of hearing loss is largely unknown. Using an inducible and conditional pericyte depletion mouse model and noise-exposed mouse model, we show that loss of pericytes leads to marked changes in vascular structure, in turn leading to vascular degeneration and hearing loss. In vitro, using advanced tissue explants from pericyte fluorescence reporter models combined with exogenous donor pericytes, we show that pericytes, signaled by VEGF isoform A165 (VEGFA165), vigorously drive new vessel growth in both adult and neonatal mouse inner ear tissue. In vivo, the delivery of an adeno-associated virus serotype 1-mediated (AAV1-mediated) VEGFA165 viral vector to pericyte-depleted or noise-exposed animals prevented and regenerated lost pericytes, improved blood supply, and attenuated hearing loss. These studies provide the first clear-cut evidence that pericytes are critical for vascular regeneration, vascular stability, and hearing in adults. The restoration of vascular function in the damaged cochlea, including in noise-exposed animals, suggests that VEGFA165 gene therapy could be a new strategy for ameliorating vascular associated hearing disorders.
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Affiliation(s)
- Jinhui Zhang
- Oregon Hearing Research Center, Department of Otolaryngology-Head & Neck Surgery, Oregon Health & Science University, Portland, Oregon, USA
| | - Zhiqiang Hou
- Oregon Hearing Research Center, Department of Otolaryngology-Head & Neck Surgery, Oregon Health & Science University, Portland, Oregon, USA
| | - Xiaohan Wang
- Oregon Hearing Research Center, Department of Otolaryngology-Head & Neck Surgery, Oregon Health & Science University, Portland, Oregon, USA.,Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Han Jiang
- Oregon Hearing Research Center, Department of Otolaryngology-Head & Neck Surgery, Oregon Health & Science University, Portland, Oregon, USA
| | - Lingling Neng
- Oregon Hearing Research Center, Department of Otolaryngology-Head & Neck Surgery, Oregon Health & Science University, Portland, Oregon, USA
| | - Yunpei Zhang
- Oregon Hearing Research Center, Department of Otolaryngology-Head & Neck Surgery, Oregon Health & Science University, Portland, Oregon, USA
| | - Qing Yu
- Oregon Hearing Research Center, Department of Otolaryngology-Head & Neck Surgery, Oregon Health & Science University, Portland, Oregon, USA
| | - George Burwood
- Oregon Hearing Research Center, Department of Otolaryngology-Head & Neck Surgery, Oregon Health & Science University, Portland, Oregon, USA
| | - Junha Song
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Manfred Auer
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Anders Fridberger
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Michael Hoa
- Auditory Development and Restoration Program, National Institute on Deafness and Other Communication Disorders (NIDCD), NIH, Bethesda, Maryland, USA
| | - Xiaorui Shi
- Oregon Hearing Research Center, Department of Otolaryngology-Head & Neck Surgery, Oregon Health & Science University, Portland, Oregon, USA
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Hou Z, Neng L, Zhang J, Cai J, Wang X, Zhang Y, Lopez IA, Shi X. Acoustic Trauma Causes Cochlear Pericyte-to-Myofibroblast-Like Cell Transformation and Vascular Degeneration, and Transplantation of New Pericytes Prevents Vascular Atrophy. THE AMERICAN JOURNAL OF PATHOLOGY 2020; 190:1943-1959. [PMID: 32562655 DOI: 10.1016/j.ajpath.2020.05.019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 05/19/2020] [Accepted: 05/26/2020] [Indexed: 12/20/2022]
Abstract
Acoustic trauma disrupts cochlear blood flow and damages sensory hair cells. Damage and regression of capillaries after acoustic trauma have long been observed, but the underlying mechanism of pathology has not been understood. We show herein that loud sound causes change of phenotype from neural/glial antigen 2 positive/α-smooth muscle actin negative to neural/glial antigen 2 positive/α-smooth muscle actin positive in some pericytes (PCs) on strial capillaries that is strongly associated with up-regulation of transforming growth factor-β1. The acoustic trauma also reduced capillary density and increased deposition of matrix proteins, particularly in the vicinity of transformed PCs. In a newly established in vitro three-dimensional endothelial cell (EC) and PC co-culture model, transformed PCs induced thicker capillary-like branches in ECs and increased collagen IV and laminin expression. Transplantation of exogenous PCs derived from neonatal day 10 mouse cochleae to acoustic traumatized cochleae, however, significantly attenuated the decreased vascular density in the stria. Transplantation of PCs pretransfected with adeno-associated virus 1-vascular endothelial growth factor-A165 under control of a hypoxia-response element markedly promotes vascular volume and blood flow, increased proliferation of PCs and ECs, and attenuated loud sound-caused loss in endocochlear potential and hearing. Our results indicate that loud sound-triggered PC transformation contributes to capillary wall thickening and regression, and young PC transplantation effectively rehabilitates the vascular regression and improves hearing.
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Affiliation(s)
- Zhiqiang Hou
- Department of Otolaryngology/Head & Neck Surgery, Oregon Hearing Research Center, Oregon Health & Science University, Portland, Oregon
| | - Lingling Neng
- Department of Otolaryngology/Head & Neck Surgery, Oregon Hearing Research Center, Oregon Health & Science University, Portland, Oregon
| | - Jinhui Zhang
- Department of Otolaryngology/Head & Neck Surgery, Oregon Hearing Research Center, Oregon Health & Science University, Portland, Oregon
| | - Jing Cai
- Department of Otolaryngology/Head & Neck Surgery, Oregon Hearing Research Center, Oregon Health & Science University, Portland, Oregon
| | - Xiaohan Wang
- Department of Otolaryngology/Head & Neck Surgery, Oregon Hearing Research Center, Oregon Health & Science University, Portland, Oregon; Center for Life Sciences, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Yunpei Zhang
- Department of Otolaryngology/Head & Neck Surgery, Oregon Hearing Research Center, Oregon Health & Science University, Portland, Oregon
| | - Ivan A Lopez
- Cellular and Molecular Biology of the Inner Ear Laboratory, Department of Head and Neck Surgery, David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Xiaorui Shi
- Department of Otolaryngology/Head & Neck Surgery, Oregon Hearing Research Center, Oregon Health & Science University, Portland, Oregon.
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4
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Schomann T, Mezzanotte L, de Groot JCMJ, Löwik CWGM, Frijns JHM, Huisman MA. Imaging Bioluminescent Exogenous Stem Cells in the Intact Guinea Pig Cochlea. Anat Rec (Hoboken) 2020; 303:427-440. [PMID: 30635981 PMCID: PMC7065152 DOI: 10.1002/ar.24068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Revised: 06/25/2018] [Accepted: 08/27/2018] [Indexed: 11/07/2022]
Abstract
Stem-cell-based therapy may be used to replace damaged or lost neurons in the cochlear nerve of patients suffering from severe-to-profound sensorineural hearing loss. In order to achieve functional recovery in future clinical trials, knowledge about survival of grafted cells and their differentiation into functional neurons is a prerequisite. This calls for non-invasive in vivo visualization of cells and long-term monitoring of their survival and fate after cochlear transplantation. We have investigated if molecular optical imaging enables visualization of exogenous cells in the intact cochlea of guinea pig cadaver heads. Transduced (stem) cells, stably co-expressing fluorescent (copGFP) and bioluminescent (Luc2) reporter molecules, were injected into the internal auditory meatus or directly into the cochlea through the round window. After injection of the cells into the internal auditory meatus, a bright bioluminescent signal was observed in the cavum conchae of the auricle, indicating that light generated by Luc2 is passing through the tympanic membrane and the external auditory meatus. Similar results were obtained after injection of the cells through the round window membrane, either directly into the scala tympani or in Rosenthal's canal within the modiolus of the basal cochlear turn. Imaging of the auditory bulla demonstrated that the bioluminescent signal passes through the tympanic membrane and crevices in the bony wall of the bulla. After opening the auditory bulla, the bioluminescent signal was emanating from the round window. This is the first study demonstrating that bioluminescence imaging enables visualization of luciferase-expressing cells injected into the intact guinea pig cochlea. Anat Rec, 303:427-440, 2020. © 2019 The Authors. The Anatomical Record published by Wiley Periodicals, Inc. on behalf of American Association of Anatomists.
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Affiliation(s)
- Timo Schomann
- Auditory Neurobiology Laboratory, Department of Otorhinolaryngology and Head and Neck SurgeryLeiden University Medical CenterLeidenThe Netherlands
| | - Laura Mezzanotte
- Optical Molecular Imaging, Department of RadiologyErasmus Medical Center RotterdamRotterdamThe Netherlands
| | - John C. M. J. de Groot
- Auditory Neurobiology Laboratory, Department of Otorhinolaryngology and Head and Neck SurgeryLeiden University Medical CenterLeidenThe Netherlands
| | - Clemens W. G. M. Löwik
- Optical Molecular Imaging, Department of RadiologyErasmus Medical Center RotterdamRotterdamThe Netherlands
| | - Johan H. M. Frijns
- Auditory Neurobiology Laboratory, Department of Otorhinolaryngology and Head and Neck SurgeryLeiden University Medical CenterLeidenThe Netherlands
| | - Margriet A. Huisman
- Auditory Neurobiology Laboratory, Department of Otorhinolaryngology and Head and Neck SurgeryLeiden University Medical CenterLeidenThe Netherlands
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5
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Nyberg S, Abbott NJ, Shi X, Steyger PS, Dabdoub A. Delivery of therapeutics to the inner ear: The challenge of the blood-labyrinth barrier. Sci Transl Med 2020; 11:11/482/eaao0935. [PMID: 30842313 DOI: 10.1126/scitranslmed.aao0935] [Citation(s) in RCA: 157] [Impact Index Per Article: 39.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 12/01/2017] [Accepted: 03/22/2018] [Indexed: 12/20/2022]
Abstract
Permanent hearing loss affects more than 5% of the world's population, yet there are no nondevice therapies that can protect or restore hearing. Delivery of therapeutics to the cochlea and vestibular system of the inner ear is complicated by their inaccessible location. Drug delivery to the inner ear via the vasculature is an attractive noninvasive strategy, yet the blood-labyrinth barrier at the luminal surface of inner ear capillaries restricts entry of most blood-borne compounds into inner ear tissues. Here, we compare the blood-labyrinth barrier to the blood-brain barrier, discuss invasive intratympanic and intracochlear drug delivery methods, and evaluate noninvasive strategies for drug delivery to the inner ear.
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Affiliation(s)
- Sophie Nyberg
- Biological Sciences, Sunnybrook Research Institute, Toronto, ON M4N 3M5, Canada
| | - N Joan Abbott
- Institute of Pharmaceutical Science, King's College London, London SE1 9NH, UK
| | - Xiaorui Shi
- Oregon Hearing Research Center, Department of Otolaryngology, Head & Neck Surgery, Oregon Health & Science University, Portland, OR 97239, USA
| | - Peter S Steyger
- Oregon Hearing Research Center, Department of Otolaryngology, Head & Neck Surgery, Oregon Health & Science University, Portland, OR 97239, USA
| | - Alain Dabdoub
- Biological Sciences, Sunnybrook Research Institute, Toronto, ON M4N 3M5, Canada. .,Department of Otolaryngology-Head & Neck Surgery, University of Toronto, Toronto, ON M5G 2C4, Canada.,Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON M5G 2C4, Canada
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6
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Kim YY, Chao JR, Kim C, Kang TC, Park HS, Chang J, Suh JG, Lee JH. Applicability of vital staining and tissue clearing to vascular anatomy and melanocytes' evaluation of temporal bone in six laboratory species. Anat Histol Embryol 2019; 48:296-305. [PMID: 30916435 DOI: 10.1111/ahe.12440] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Revised: 02/11/2019] [Accepted: 02/26/2019] [Indexed: 12/14/2022]
Abstract
The purpose of the present study was to define the applicability of tissue clearing to the field of otology. We combined tissue clearing with vital staining perfusion via a pumping system to examine the vascular anatomy of temporal bones in laboratory animals. We used six different types of species including Korean wild mouse, mouse, Mongolian gerbil, hamsters and Guinea pigs. A mixture of Alcian blue reagent and 4% paraformaldehyde was circulated throughout the entire circulatory system of the animal via a perfusion pump system. Transparency images were obtained from the temporal bones according to the protocol of the SunHyun 3D Imaging Kit. In examining the inner surface of the tympanic membrane, flaccid part (pars flaccida) was positioned along the entire marginal area in Guinea pig. In the Guinea pig, unlike the other species, the cortical bone of the mastoid (bullae) was easily removed using cold instruments, allowing a direct approach to the enclosed structures. The distribution and pattern of cochlea melanocytes were compared among the species. "Mobius strip"-like accumulated melanocytes in vestibules were shown in both the Korean wild mouse and mouse. The collateral blood supply to the cochlea in six different species was checked in various pattern. Combining dye infusion with tissue-clearing techniques, we documented the middle ear and transparent inner ear structures in six different species. The information and associated images will help other researchers to develop hypotheses and design experimental investigations.
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Affiliation(s)
- Yoo Yeon Kim
- Department of Medical Genetics, College of Medicine, Hallym University, Chuncheon, Korea
| | - Janet Ren Chao
- Division of Otolaryngology, Department of Surgery, Yale School of Medicine, New Haven, Connecticut
| | - Chulho Kim
- Department of Neurology, Chuncheon Sacred Heart Hospital, Hallym University, Chuncheon, Korea
| | - Tae-Cheon Kang
- Department of Anatomy and Neurobiology, College of Medicine, Hallym University, Chuncheon, Korea
| | - Hae Sang Park
- Institute of New Frontier Research, Hallym University College of Medicine, Chuncheon, Korea.,Department of Otorhinolaryngology-Head and Neck Surgery, College of Medicine, Hallym University, Chuncheon, Korea
| | - Jiwon Chang
- Department of Otorhinolaryngology-Head and Neck Surgery, College of Medicine, Hallym University, Chuncheon, Korea
| | - Jun-Gyo Suh
- Department of Medical Genetics, College of Medicine, Hallym University, Chuncheon, Korea
| | - Jun Ho Lee
- Institute of New Frontier Research, Hallym University College of Medicine, Chuncheon, Korea.,Department of Otorhinolaryngology-Head and Neck Surgery, College of Medicine, Hallym University, Chuncheon, Korea
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7
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Hou Z, Wang X, Cai J, Zhang J, Hassan A, Auer M, Shi X. Platelet-Derived Growth Factor Subunit B Signaling Promotes Pericyte Migration in Response to Loud Sound in the Cochlear Stria Vascularis. J Assoc Res Otolaryngol 2018; 19:363-379. [PMID: 29869048 PMCID: PMC6081892 DOI: 10.1007/s10162-018-0670-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 04/19/2018] [Indexed: 12/20/2022] Open
Abstract
Normal blood supply to the cochlea is critical for hearing. Noise damages auditory sensory cells and has a marked effect on the microvasculature in the cochlear lateral wall. Pericytes in the stria vascularis (strial pericytes) are particularly vulnerable and sensitive to acoustic trauma. Exposure of NG2DsRedBAC transgenic mice (6-8 weeks old) to wide-band noise at a level of 120 dB for 3 h per day for 2 consecutive days produced a significant hearing threshold shift and caused pericytes to protrude and migrate from their normal endothelial attachment sites. The pericyte migration was associated with increased expression of platelet-derived growth factor beta (PDGF-BB). Blockade of PDGF-BB signaling with either imatinib, a potent PDGF-BB receptor (PDGFR) inhibitor, or APB5, a specific PDGFRβ blocker, significantly attenuated the pericyte migration from strial vessel walls. The PDGF-BB-mediated strial pericyte migration was further confirmed in an in vitro cell migration assay, as well as in an in vivo live animal model used in conjunction with confocal fluorescence microscopy. Pericyte migration took one of two different forms, here denoted protrusion and detachment. The protrusion is characterized by pericytes with a prominent triangular shape, or pericytes extending fine strands to neighboring capillaries. The detachment is characterized by pericyte detachment and movement away from vessels. We also found the sites of pericyte migration highly associated with regions of vascular leakage. In particular, under transmission electron microscopy (TEM), multiple vesicles at the sites of endothelial cells with loosely attached pericytes were observed. These data show that cochlear pericytes are markedly affected by acoustic trauma, causing them to display abnormal morphology. The effect of loud sound on pericytes is mediated by upregulation of PDGF-BB. Normal functioning pericytes are required for vascular stability.
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Affiliation(s)
- Zhiqiang Hou
- Oregon Hearing Research Center, Department of Otolaryngology/Head & Neck Surgery, Oregon Health & Science University, Portland, OR, 97239, USA
| | - Xiaohan Wang
- Oregon Hearing Research Center, Department of Otolaryngology/Head & Neck Surgery, Oregon Health & Science University, Portland, OR, 97239, USA
| | - Jing Cai
- Oregon Hearing Research Center, Department of Otolaryngology/Head & Neck Surgery, Oregon Health & Science University, Portland, OR, 97239, USA
| | - Jinhui Zhang
- Oregon Hearing Research Center, Department of Otolaryngology/Head & Neck Surgery, Oregon Health & Science University, Portland, OR, 97239, USA
| | - Ahmed Hassan
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Manfred Auer
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Xiaorui Shi
- Oregon Hearing Research Center, Department of Otolaryngology/Head & Neck Surgery, Oregon Health & Science University, Portland, OR, 97239, USA.
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8
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Wang X. The Structure and the Function of the Cochlear Intra-Strial Fluid-Blood Barrier. OTOLARYNGOLOGY (SUNNYVALE, CALIF.) 2017; 7. [PMID: 33282527 PMCID: PMC7713702 DOI: 10.4172/2161-119x.1000308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- Xiaohan Wang
- Department of Otolaryngology/Head and Neck Surgery, Oregon Hearing Research Center, Oregon Health and Science University, USA
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9
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Brown DJ, Pastras CJ, Curthoys IS, Southwell CS, Van Roon L. Endolymph movement visualized with light sheet fluorescence microscopy in an acute hydrops model. Hear Res 2016; 339:112-24. [PMID: 27377233 DOI: 10.1016/j.heares.2016.06.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Revised: 05/30/2016] [Accepted: 06/13/2016] [Indexed: 10/21/2022]
Abstract
There are a variety of techniques available to investigate endolymph dynamics, primarily seeking to understand the cause of endolymphatic hydrops. Here we have taken the novel approach of injecting, via a glass micropipette, fluorescein isothiocyanate-dextran (FITC-dex) and artificial endolymph into scala media of anaesthetized guinea pigs, with subsequent imaging of the inner ear using Light Sheet Fluorescence Microscopy (LSFM) as a means to obtain highly resolved 3D visualization of fluid movements. Our results demonstrate endolymph movement into the utricle, semicircular canals and endolymphatic duct and sac when more than 2.5 μl of fluid had been injected into scala media, with no apparent movement of fluid into the perilymphatic compartments. There was no movement of endolymph into these compartments when less than 2.5 μl was injected. The remarkable uptake of the FITC-dex into the endolymphatic duct, including an absorption into the periductal channels surrounding the endolymphatic duct, highlights the functional role this structure plays in endolymph volume regulation.
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Affiliation(s)
- Daniel J Brown
- Sydney Medical School, The University of Sydney, Sydney, NSW, 2050, Australia.
| | | | - Ian S Curthoys
- Vestibular Research Laboratory, The University of Sydney, School of Psychology, Sydney, NSW, 2050, Australia
| | | | - Lieke Van Roon
- University of Utrecht, Faculty Nature and Technique, Inst. for Life Sciences and Chemistry, Utrecht, 3508 AD, The Netherlands
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10
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Pathophysiology of the cochlear intrastrial fluid-blood barrier (review). Hear Res 2016; 338:52-63. [PMID: 26802581 DOI: 10.1016/j.heares.2016.01.010] [Citation(s) in RCA: 138] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Revised: 01/11/2016] [Accepted: 01/14/2016] [Indexed: 12/20/2022]
Abstract
The blood-labyrinth barrier (BLB) in the stria vascularis is a highly specialized capillary network that controls exchanges between blood and the intrastitial space in the cochlea. The barrier shields the inner ear from blood-born toxic substances and selectively passes ions, fluids, and nutrients to the cochlea, playing an essential role in the maintenance of cochlear homeostasis. Anatomically, the BLB is comprised of endothelial cells (ECs) in the strial microvasculature, elaborated tight and adherens junctions, pericytes (PCs), basement membrane (BM), and perivascular resident macrophage-like melanocytes (PVM/Ms), which together form a complex "cochlear-vascular unit" in the stria vascularis. Physical interactions between the ECs, PCs, and PVM/Ms, as well as signaling between the cells, is critical for controlling vascular permeability and providing a proper environment for hearing function. Breakdown of normal interactions between components of the BLB is seen in a wide range of pathological conditions, including genetic defects and conditions engendered by inflammation, loud sound trauma, and ageing. In this review, we will discuss prevailing views of the structure and function of the strial cochlear-vascular unit (also referred to as the "intrastrial fluid-blood barrier"). We will also discuss the disrupted homeostasis seen in a variety of hearing disorders. Therapeutic targeting of the strial barrier may offer opportunities for improvement of hearing health and amelioration of auditory disorders. This article is part of a Special Issue entitled <Annual Reviews 2016>.
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11
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Zhang J, Chen S, Hou Z, Cai J, Dong M, Shi X. Lipopolysaccharide-induced middle ear inflammation disrupts the cochlear intra-strial fluid-blood barrier through down-regulation of tight junction proteins. PLoS One 2015; 10:e0122572. [PMID: 25815897 PMCID: PMC4376743 DOI: 10.1371/journal.pone.0122572] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 02/16/2015] [Indexed: 12/20/2022] Open
Abstract
Middle ear infection (or inflammation) is the most common pathological condition that causes fluid to accumulate in the middle ear, disrupting cochlear homeostasis. Lipopolysaccharide, a product of bacteriolysis, activates macrophages and causes release of inflammatory cytokines. Many studies have shown that lipopolysaccharides cause functional and structural changes in the inner ear similar to that of inflammation. However, it is specifically not known how lipopolysaccharides affect the blood-labyrinth barrier in the stria vascularis (intra-strial fluid–blood barrier), nor what the underlying mechanisms are. In this study, we used a cell culture-based in vitro model and animal-based in vivo model, combined with immunohistochemistry and a vascular leakage assay, to investigate lipopolysaccharide effects on the integrity of the mouse intra-strial fluid–blood barrier. Our results show lipopolysaccharide-induced local infection significantly affects intra-strial fluid–blood barrier component cells. Pericytes and perivascular-resident macrophage-like melanocytes are particularly affected, and the morphological and functional changes in these cells are accompanied by substantial changes in barrier integrity. Significant vascular leakage is found in the lipopolysaccharide treated-animals. Consistent with the findings from the in vivo animal model, the permeability of the endothelial cell monolayer to FITC-albumin was significantly higher in the lipopolysaccharide-treated monolayer than in an untreated endothelial cell monolayer. Further study has shown the lipopolysaccharide-induced inflammation to have a major effect on the expression of tight junctions in the blood barrier. Lipopolysaccharide was also shown to cause high frequency hearing loss, corroborated by previous reports from other laboratories. Our findings show lipopolysaccharide-evoked middle ear infection disrupts inner ear fluid balance, and its particular effects on the intra-strial fluid–blood barrier, essential for cochlear homeostasis. The barrier is degraded as the expression of tight junction-associated proteins such as zona occludens 1, occludin, and vascular endothelial cadherin are down-regulated.
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Affiliation(s)
- Jinhui Zhang
- Department of Otolaryngology/Head and Neck Surgery, First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
- Oregon Hearing Research Center, Department of Otolaryngology/Head and Neck Surgery, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Songlin Chen
- Oregon Hearing Research Center, Department of Otolaryngology/Head and Neck Surgery, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Zhiqiang Hou
- Oregon Hearing Research Center, Department of Otolaryngology/Head and Neck Surgery, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Jing Cai
- Oregon Hearing Research Center, Department of Otolaryngology/Head and Neck Surgery, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Mingmin Dong
- Department of Otolaryngology/Head and Neck Surgery, First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
| | - Xiaorui Shi
- Oregon Hearing Research Center, Department of Otolaryngology/Head and Neck Surgery, Oregon Health & Science University, Portland, Oregon, United States of America
- * E-mail:
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