Tension fibroblasts and the connective tissue matrix of the spiral ligament

Henson, Miriam M.; Henson, O. W.

doi:10.1016/0378-5955(88)90121-9

Cited by 60 publications

(46 citation statements)

References 21 publications

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“…cx43-dependent contraction has also been reported in dermal fibroblast-populated collagen gels (Ehrlich et al 2000), leading to speculation that cx43 may be important in the organization of extracellular collagen fibers in vivo. In the spiral ligament, type III fibrocytes are proposed to exert effects on basilar membrane tension by interacting with extracellular collagen-containing anchoring fibers that extend between the hyaline attachment zone of the basilar membrane and the otic capsule (Henson and Henson 1988;Dreiling et al 2002;Naidu and Mountain 2007). We propose that the gain of this nmII-dependent tensioning process is set via cx43-dependent GJIC between type III fibrocytes.…”

Section: Contractility In Type III Fibrocytes Is Modulated By Gap Junmentioning

confidence: 88%

“…The physical properties of the type III fibrocyte compartment should vary along the tonotopic axis of the spiral ligament. These cells are most numerous in the basal region of the cochlea (Henson and Henson 1988), and it is in this region that they are most heavily endowed with acto-myosin cytoskeletal elements. This suggests that type III fibrocyte contractility contributes mostly to high frequency sound-coding.…”

Section: Contractile Type III Fibrocytes Can Be Derived From the Cultmentioning

confidence: 99%

“…They appear not to be connected cytoplasmically to the connective tissue gap junction network (Kelly et al 2011) but may form a separately coupled compartment via cx43-containing channels . Based solely on their extensive expression of contractile cytoskeletal elements, including nmII and bundles of actin filaments, they have also been termed "tension fibrocytes" (Henson et al 1984;Henson et al 1985;Henson and Henson 1988), and have been proposed to regulate the micromechanics of the spiral ligamentbasilar membrane complex (Naidu and Mountain 2007). However, due to their inaccessibility in vivo there is little, if any, direct experimental evidence to support this hypothesis.…”

Section: Introductionmentioning

confidence: 99%

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Contractility in Type III Cochlear Fibrocytes Is Dependent on Non-muscle Myosin II and Intercellular Gap Junctional Coupling

Kelly

Forge

Jagger

2012

JARO

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The cochlear spiral ligament is a connective tissue that plays diverse roles in normal hearing. Spiral ligament fibrocytes are classified into functional subtypes that are proposed to carry out specialized roles in fluid homeostasis, the mediation of inflammatory responses to trauma, and the fine tuning of cochlear mechanics. We derived a secondary sub-culture from guinea pig spiral ligament, in which the cells expressed protein markers of type III or "tension" fibrocytes, including non-muscle myosin II (nmII), α-smooth muscle actin (αsma), vimentin, connexin43 (cx43), and aquaporin-1. The cells formed extensive stress fibers containing αsma, which were also associated intimately with nmII expression, and the cells displayed the mechanically contractile phenotype predicted by earlier modeling studies. cx43 immunofluorescence was evident within intercellular plaques, and the cells were coupled via dye-permeable gap junctions. Coupling was blocked by meclofenamic acid (MFA), an inhibitor of cx43-containing channels. The contraction of collagen lattice gels mediated by the cells could be prevented reversibly by blebbistatin, an inhibitor of nmII function. MFA also reduced the gel contraction, suggesting that intercellular coupling modulates contractility. The results demonstrate that these cells can impart nmII-dependent contractile force on a collagenous substrate, and support the hypothesis that type III fibrocytes regulate tension in the spiral ligament-basilar membrane complex, thereby determining auditory sensitivity.

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Section: Contractility In Type III Fibrocytes Is Modulated By Gap Junmentioning

confidence: 88%

Section: Contractile Type III Fibrocytes Can Be Derived From the Cultmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Contractility in Type III Cochlear Fibrocytes Is Dependent on Non-muscle Myosin II and Intercellular Gap Junctional Coupling

Kelly

Forge

Jagger

2012

JARO

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“…38,39 The spiral ligament in the normal canine ear showed a compartmentalization of type IV collagen expression with the ␣1 and ␣2 chains in the region of attachment of the basilar membrane (among root cells of the spiral ligament) and strong expression of the ␣3, ␣4, and ␣5 chains in a separate region along the lateral edge of the spiral ligament, which is populated by cells known as tension fibroblasts. 40,41 This region was notably devoid of the ␣1 and ␣2 chains. Results of other studies have varied for this region of the inner ear, with a more diffuse staining noted for the ␣1 chain 24 and no staining for the ␣3, ␣4, and ␣5 chains.…”

Section: Discussionmentioning

confidence: 99%

“…This region is populated by myofibroblastic cells termed "tension fibroblasts." 40,41 These cells connect the bony wall of the inner ear to the basilar membrane through a network of extracellular fibers and are believed to help maintain tension on the basilar membrane. Such cells contain various contractile proteins including actin, ␣-actinin, myosin, and tropomyosin.…”

Section: Discussionmentioning

confidence: 99%

The Inner Ear of Dogs with X-Linked Nephritis Provides Clues to the Pathogenesis of Hearing Loss in X-Linked Alport Syndrome

Harvey

Mount

Sado

et al. 2001

The American Journal of Pathology

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Alport syndrome is an inherited disorder of type IV collagen with progressive nephropathy, ocular abnormalities, and high-tone sensorineural deafness. In X-linked Alport syndrome, mutations in the COL4A5 gene encoding the ␣5 chain of type IV collagen lead to loss of the ␣3/␣4/␣5 network and increased susceptibility of the glomerular basement membrane to long-term damage. The molecular defects that underlie the otopathology in this disease remain poorly understood. We used a canine model of X-linked Alport syndrome to determine the expression of type IV collagen ␣-chains in the inner ear. By 1 month in normal adult dogs, the ␣3, ␣4, and ␣5 chains were co-expressed in a thin continuous line extending along the basilar membrane and the internal and external sulci, with the strongest expression along the lateral aspect of the spiral ligament in the basal turn of the cochlea. Affected dogs showed complete absence of the ␣3/␣4/␣5 network. The lateral aspect of the spiral ligament is populated by tension fibroblasts that express ␣-smooth muscle actin and nonmuscle myosin and are postulated to generate radial tension on the basilar membrane via the extracellular matrix for reception of high frequency sound. We propose that in Alport syndrome, the loss of the ␣3/␣4/␣5 network eventually weakens the interaction of these cells with their extracellular matrix, resulting in reduced tension on the basilar membrane and the inability to respond to high frequency sounds.

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Human Cochlea: Anatomical Characteristics and their Relevance for Cochlear Implantation

Rask‐Andersen

Liu

Erixon

et al. 2012

The Anatomical Record

144

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This is a review of the anatomical characteristics of human cochlea and the importance of variations in this anatomy to the process of cochlear implantation (CI). Studies of the human cochlea are essential to better comprehend the physiology and pathology of man's hearing. The human cochlea is difficult to explore due to its vulnerability and bordering capsule. Inner ear tissue undergoes quick autolytic changes making investigations of autopsy material difficult, even though excellent results have been presented over time. Important issues today are novel inner ear therapies including CI and new approaches for inner ear pharmacological treatments. Inner ear surgery is now a reality, and technical advancements in the design of electrode arrays and surgical approaches allow preservation of remaining structure/function in most cases. Surgeons should aim to conserve cochlear structures for future potential stem cell and gene therapies. Renewal interest of round window approaches necessitates further acquaintance of this complex anatomy and its variations. Rough cochleostomy drilling at the intricate ''hook'' region can generate intracochlear bone-dust-inducing fibrosis and new bone formation, which could negatively influence auditory nerve responses at a later time point. Here, we present macro-and microanatomic investigations of the human cochlea viewing the extensive anatomic variations that influence electrode insertion. In addition, electron microscopic (TEM and SEM) and immunohistochemical results, based on specimens removed at surgeries for lifethreatening petroclival meningioma and some well-preserved postmortal tissues, are displayed. These give us new information about structure as well as protein and molecular expression in man. Our aim was not to formulate a complete description of the complex human anatomy but to focus on aspects clinically relevant for electric stimulation, predominantly, the sensory targets, and how surgical atraumaticity best could be reached.

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Tension fibroblasts and the connective tissue matrix of the spiral ligament

Cited by 60 publications

References 21 publications

Contractility in Type III Cochlear Fibrocytes Is Dependent on Non-muscle Myosin II and Intercellular Gap Junctional Coupling

Contractility in Type III Cochlear Fibrocytes Is Dependent on Non-muscle Myosin II and Intercellular Gap Junctional Coupling

The Inner Ear of Dogs with X-Linked Nephritis Provides Clues to the Pathogenesis of Hearing Loss in X-Linked Alport Syndrome

Human Cochlea: Anatomical Characteristics and their Relevance for Cochlear Implantation

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