scholarly journals Hair Cell Generation in Cochlear Culture Models Mediated by Novel γ-Secretase Inhibitors

2021 ◽  
Vol 9 ◽  
Author(s):  
Silvia T. Erni ◽  
John C. Gill ◽  
Carlotta Palaferri ◽  
Gabriella Fernandes ◽  
Michelle Buri ◽  
...  
Keyword(s):  
Hair Cell ◽  
Notch Signaling ◽  
Hair Cells ◽  
Round Window ◽  
Notch Pathway ◽  
Outer Hair Cells ◽  
Round Window Membrane ◽  
Sensory Cells ◽  
Supporting Cells

Sensorineural hearing loss is prevalent within society affecting the quality of life of 460 million worldwide. In the majority of cases, this is due to insult or degeneration of mechanosensory hair cells in the cochlea. In adult mammals, hair cell loss is irreversible as sensory cells are not replaced spontaneously. Genetic inhibition of Notch signaling had been shown to induce hair cell formation by transdifferentiation of supporting cells in young postnatal rodents and provided an impetus for targeting Notch pathway with small molecule inhibitors for hearing restoration. Here, the oto-regenerative potential of different γ-secretase inhibitors (GSIs) was evaluated in complementary assay models, including cell lines, organotypic cultures of the organ of Corti and cochlear organoids to characterize two novel GSIs (CPD3 and CPD8). GSI-treatment induced hair cell gene expression in all these models and was effective in increasing hair cell numbers, in particular outer hair cells, both in baseline conditions and in response to ototoxic damage. Hair cells were generated from transdifferentiation of supporting cells. Similar findings were obtained in cochlear organoid cultures, used for the first time to probe regeneration following sisomicin-induced damage. Finally, effective absorption of a novel GSI through the round window membrane and hair cell induction was attained in a whole cochlea culture model and in vivo pharmacokinetic comparisons of transtympanic delivery of GSIs and different vehicle formulations were successfully conducted in guinea pigs. This preclinical evaluation of targeting Notch signaling with novel GSIs illustrates methods of characterization for hearing restoration molecules, enabling translation to more complex animal studies and clinical research.

scholarly journals Hear, Hear for Notch: Control of Cell Fates in the Inner Ear by Notch Signaling

Biomolecules ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 370 ◽  
Author(s):  
Rogers Brown ◽  
Andrew K. Groves
Keyword(s):  
Hair Cell ◽  
Notch Signaling ◽  
Inner Ear ◽  
Hair Cells ◽  
Notch Pathway ◽  
Notch Signaling Pathway ◽  
Cell Regeneration ◽  
Hair Cell Regeneration ◽  
Supporting Cells ◽  
Fine Grained

The vertebrate inner ear is responsible for detecting sound, gravity, and head motion. These mechanical forces are detected by mechanosensitive hair cells, arranged in a series of sensory patches in the vestibular and cochlear regions of the ear. Hair cells form synapses with neurons of the VIIIth cranial ganglion, which convey sound and balance information to the brain. They are surrounded by supporting cells, which nourish and protect the hair cells, and which can serve as a source of stem cells to regenerate hair cells after damage in non-mammalian vertebrates. The Notch signaling pathway plays many roles in the development of the inner ear, from the earliest formation of future inner ear ectoderm on the side of the embryonic head, to regulating the production of supporting cells, hair cells, and the neurons that innervate them. Notch signaling is re-deployed in non-mammalian vertebrates during hair cell regeneration, and attempts have been made to manipulate the Notch pathway to promote hair cell regeneration in mammals. In this review, we summarize the different modes of Notch signaling in inner ear development and regeneration, and describe how they interact with other signaling pathways to orchestrate the fine-grained cellular patterns of the ear.

scholarly journals Umbilical Cord Mesenchymal Stromal Cell-Derived Exosomes Rescue the Loss of Outer Hair Cells and Repair Cochlear Damage in Cisplatin-Injected Mice

2021 ◽  
Vol 22 (13) ◽  
pp. 6664
Author(s):  
Stella Chin-Shaw Tsai ◽  
Kuender D. Yang ◽  
Kuang-Hsi Chang ◽  
Frank Cheau-Feng Lin ◽  
Ruey-Hwang Chou ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Umbilical Cord ◽  
Hair Cells ◽  
Round Window ◽  
Outer Hair Cells ◽  
Protective Effects ◽  
Cochlear Hair Cells ◽  
Potential Applications ◽  
Round Window Niche

Umbilical cord-derived mesenchymal stromal cells (UCMSCs) have potential applications in regenerative medicine. UCMSCs have been demonstrated to repair tissue damage in many inflammatory and degenerative diseases. We have previously shown that UCMSC exosomes reduce nerve injury-induced pain in rats. In this study, we characterized UCMSC exosomes using RNA sequencing and proteomic analyses and investigated their protective effects on cisplatin-induced hearing loss in mice. Two independent experiments were designed to investigate the protective effects on cisplatin-induced hearing loss in mice: (i) chronic intraperitoneal cisplatin administration (4 mg/kg) once per day for 5 consecutive days and intraperitoneal UCMSC exosome (1.2 μg/μL) injection at the same time point; and (ii) UCMSC exosome (1.2 μg/μL) injection through a round window niche 3 days after chronic cisplatin administration. Our data suggest that UCMSC exosomes exert protective effects in vivo. The post-traumatic administration of UCMSC exosomes significantly improved hearing loss and rescued the loss of cochlear hair cells in mice receiving chronic cisplatin injection. Neuropathological gene panel analyses further revealed the UCMSC exosomes treatment led to beneficial changes in the expression levels of many genes in the cochlear tissues of cisplatin-injected mice. In conclusion, UCMSC exosomes exerted protective effects in treating ototoxicity-induced hearing loss by promoting tissue remodeling and repair.

scholarly journals Dual expression of Atoh1 and Ikzf2 promotes transformation of adult cochlear supporting cells into outer hair cells

2021 ◽  
Author(s):  
Suhong Sun ◽  
Shuting Li ◽  
Zhengnan Luo ◽  
Minhui Ren ◽  
Shunji He ◽  
...  
Keyword(s):  
Single Cell ◽  
Hearing Impairment ◽  
Hair Cells ◽  
Outer Hair Cells ◽  
Supporting Cells ◽  
Differentiation Status ◽  
Cochlear Supporting Cells ◽  
Simultaneous Expression ◽  
Dual Expression

ABSTRACTMammalian cochlear outer hair cells (OHCs) are essential for hearing. OHC degeneration causes severe hearing impairment. Previous attempts of regenerating new OHCs from cochlear supporting cells (SCs) had yielded cells lacking Prestin, a key motor protein for OHC function. Thus, regeneration of Prestin+ OHCs remains a challenge for repairing OHC damage in vivo. Here, we reported that successful in vivo conversion of adult cochlear SCs into Prestin+ OHC-like cells could be achieved by simultaneous expression of Atoh1 and Ikzf2, two key transcriptional factors necessary for OHC development. New OHC-like cells exhibited upregulation of hundreds of OHC genes and downregulation of SC genes. Single cell transcriptomic analysis demonstrated that the differentiation status of these OHC-like cells was much more advanced than previously achieved. Thus, we have established an efficient approach to promote regeneration of Prestin+ OHCs and paved the way for repairing damaged cochlea in vivo via transdifferentiation of SCs.

scholarly journals Dual expression of Atoh1 and Ikzf2 promotes transformation of adult cochlear supporting cells into outer hair cells

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Suhong Sun ◽  
Shuting Li ◽  
Zhengnan Luo ◽  
Minhui Ren ◽  
Shunji He ◽  
...  
Keyword(s):  
Hair Cells ◽  
Adult Mouse ◽  
Outer Hair Cells ◽  
Auditory Function ◽  
Supporting Cells ◽  
Single Cell Rna Sequencing ◽  
Differentiation Status ◽  
Cochlear Supporting Cells ◽  
Dual Expression

Mammalian cochlear outer hair cells (OHCs) are essential for hearing. Severe hearing impairment follows OHC degeneration. Previous attempts at regenerating new OHCs from cochlear supporting cells (SCs) have been unsuccessful, notably lacking expression of the key OHC motor protein, Prestin. Thus, regeneration of Prestin+ OHCs represents a barrier to restore auditory function in vivo. Here, we reported the successful in vivo conversion of adult mouse cochlear SCs into Prestin+ OHC-like cells through the concurrent induction of two key transcriptional factors known to be necessary for OHC development: Atoh1 and Ikzf2. Single-cell RNA sequencing revealed the upregulation of 729 OHC genes and downregulation of 331 SC genes in OHC-like cells. The resulting differentiation status of these OHC-like cells was much more advanced than previously achieved. This study thus established an efficient approach to induce the regeneration of Prestin+ OHCs, paving the way for in vivo cochlear repair via SC transdifferentiation.

Notch signaling regulates the pattern of auditory hair cell differentiation in mammals

Development ◽  
2000 ◽  
Vol 127 (15) ◽  
pp. 3373-3383 ◽  
Author(s):  
A. Zine ◽  
T.R. Van De Water ◽  
F. de Ribaupierre
Keyword(s):  
Cell Differentiation ◽  
Hair Cell ◽  
Notch Signaling ◽  
Cell Fate ◽  
Hair Cells ◽  
Expression Patterns ◽  
Sensory Epithelium ◽  
Supporting Cells ◽  
Hair Cell Differentiation ◽  
Notch1 Signaling Pathway

The development of the mammalian cochlea is an example of patterning in the peripheral nervous system. Sensory hair cells and supporting cells in the cochlea differentiate via regional and cell fate specification. The Notch signaling components shows both distinct and overlapping expression patterns of Notch1 receptor and its ligands Jagged1 (Jag1) and Jagged2 (Jag2) in the developing auditory epithelium of the rat. On embryonic day 16 (E16), many precursor cells within the Kolliker's organ immunostained for the presence of both Notch1 and Jag1, while the area of hair cell precursors did not express either Notch1 and Jag1. During initial events of hair cell differentiation between E18 and birth, Notch1 and Jag1 expression predominated in supporting cells and Jag2 in nascent hair cells. Early after birth, Jag2 expression decreased in hair cells while the pattern of Notch1 expression now included both supporting cells and hair cells. We show that the normal pattern of hair cell differentiation is disrupted by alteration of Notch signaling. A decrease of either Notch1 or Jag1 expression by antisense oligonucleotides in cultures of the developing sensory epithelium resulted in an increase in the number of hair cells. Our data suggest that the Notch1 signaling pathway is involved in a complex interplay between the consequences of different ligand-Notch1 combinations during cochlear morphogenesis and the phases of hair cell differentiation.

scholarly journals β-Catenin is required for radial cell patterning and identity in the developing mouse cochlea

2019 ◽  
Vol 116 (42) ◽  
pp. 21054-21060 ◽  
Author(s):  
Lina Jansson ◽  
Michael Ebeid ◽  
Jessica W. Shen ◽  
Tara E. Mokhtari ◽  
Lee A. Quiruz ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Hair Cell ◽  
Hair Cells ◽  
Organ Of Corti ◽  
Outer Hair Cells ◽  
Supporting Cells ◽  
Aberrant Expression ◽  
Cell Identity ◽  
Pillar Cell ◽  
Radial Patterning

Development of multicellular organs requires the coordination of cell differentiation and patterning. Critical for sound detection, the mammalian organ of Corti contains functional units arranged tonotopically along the cochlear turns. Each unit consists of sensory hair cells intercalated by nonsensory supporting cells, both specified and radially patterned with exquisite precision during embryonic development. However, how cell identity and radial patterning are jointly controlled is poorly understood. Here we show that β-catenin is required for specification of hair cell and supporting cell subtypes and radial patterning of the cochlea in vivo. In 2 mouse models of conditional β-catenin deletion, early specification of Myosin7-expressing hair cells and Prox1-positive supporting cells was preserved. While β-catenin-deficient cochleae expressed FGF8 and FGFR3, both of which are essential for pillar cell specification, the radial patterning of organ of Corti was disrupted, revealed by aberrant expression of cadherins and the pillar cell markers P75 and Lgr6. Moreover, β-catenin ablation caused duplication of FGF8-positive inner hair cells and reduction of outer hair cells without affecting the overall hair cell density. In contrast, in another transgenic model with suppressed transcriptional activity of β-catenin but preserved cell adhesion function, both specification and radial patterning of the organ of Corti were intact. Our study reveals specific functions of β-catenin in governing cell identity and patterning mediated through cell adhesion in the developing cochlea.

scholarly journals In vivo optogenetics reveals homeostatic control of cochlear sensitivity by supporting cells

2020 ◽  
Author(s):  
Victoria Lukashkina ◽  
Snezana Levic ◽  
Patricio Simões ◽  
Zhenhang Xu ◽  
Joseph DiGuiseppi ◽  
...  
Keyword(s):  
Hair Cells ◽  
Dynamic Range ◽  
Organ Of Corti ◽  
Feedback System ◽  
Supporting Cell ◽  
Outer Hair Cells ◽  
Supporting Cells ◽  
Cochlear Supporting Cells

Abstract We used optogenetics to investigate the control of auditory sensitivity by cochlear supporting cells that scaffold outer hair cells, which transduce and amplify cochlear responses to sound. In vivo and in vitro measurements of sound-induced cochlear mechanical and electrical responses were made from mice that conditionally expressed nonselective cationic channelrhodopsins in Deiters’ and outer pillar supporting cells in the organ of Corti. We demonstrated that cochlear light-stimulation and subsequent activation of channelrhodopsins depolarized the supporting cells, changed their extracellular electrical environment, and sensitized insensitive and desensitized sensitive cochlear responses to sound. We concluded that outer hair cells, Deiters’ cells and outer pillar cells interact through feedback which regulates their immediate ionic and electrical environment and controls energy flow in the mammalian cochlea to optimize its performance over its entire dynamic range. Activation of the supporting cell channelrhodopsins shunts this feedback system and restores cochlear sensitivity to a set level.

Promotion of in Vitro Hair Cell-like Cell Differentiation from Human Embryonic Stem Cells through the Regulation of Notch Signaling

2021 ◽  
Author(s):  
Fengjiao Chen ◽  
Ying Yang ◽  
Jianling Chen ◽  
Zihua Tang ◽  
Qian Peng ◽  
...  
Keyword(s):  
Stem Cells ◽  
Embryonic Stem Cells ◽  
Hair Cell ◽  
Notch Signaling ◽  
Hair Cells ◽  
Embryonic Stem ◽  
In Vitro Differentiation ◽  
Supporting Cells ◽  
Notch Ligands

Abstract Background Notch signaling mediates the committed induced differentiation of ear sensory cells and promotes the formation of a precise arrangement of mosaics between hair cells and supporting cells. Embryonic stem cells (ESCs) are pluripotent stem cells which have the potential to differentiate into cell lines through three germ layers. Therefore, it is necessary to study the effects of regulating Notch receptors and ligand expression on the in vitro differentiation equilibrium of hair cells and supporting cells from ESCs.Methods and Results The temporal ex-pression pattern of Notch ligands and receptors during in vitro hair cell-like cell differentia-tion from human embryonic stem cells (hESCs) was detected by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Subsequently, pAJ-U6-shRNA-CMV-Puro/GFP recombinant lentiviral vectors, encoding short hairpin RNAs, were used to silence JAG-1, JAG-2, and DLL-1, according to the temporal expression pattern of Notch ligands. Then the effect of each ligand on the in vitro differentiation of hair cells was examined by RT-PCR, immunofluorescence, and scanning electron microscopy (SEM).Conclusions Results showed that JAG-1 played an important role in regulating hESC differentiation to otic progenitors. The individual deletion of JAG-2 or DLL-1 had no significant effect on the differentiation of hair cell-like cells. Although the simultaneous inhibition of both DLL-1 and JAG-2 could increase the number of hair cell-like cells, it decreased the number of supporting cells.

scholarly journals Chicken Auditory Supporting Cells Express Interferon Response Genes during Regeneration towards Nascent Sensory Hair Cells In Vivo

2021 ◽  
Author(s):  
Amanda S Janesick ◽  
Mirko Scheibinger ◽  
Nesrine Benkafadar ◽  
Sakin Kirti ◽  
Stefan Heller
Keyword(s):  
Hair Cell ◽  
Hair Cells ◽  
Cell Loss ◽  
Basilar Papilla ◽  
Interferon Response ◽  
Hair Cell Loss ◽  
Supporting Cells ◽  
Sensory Hair ◽  
Sensory Hair Cells

The avian hearing organ is the basilar papilla that, in sharp contrast to the mammalian cochlea, can regenerate sensory hair cells and thereby recover from complete deafness within weeks. The mechanisms that trigger, sustain, and terminate the regenerative response in vivo are largely unknown. Here, we profile the changes in gene expression in the chicken basilar papilla after aminoglycoside antibiotic-induced hair cell loss using RNA-sequencing. The most prominent changes in gene expression were linked to the upregulation of interferon response genes which occurred in supporting cells, confirmed by single-cell RNA-sequencing and in situ hybridization. We determined that the JAK/STAT signaling pathway is essential for the interferon gene response in supporting cells, set in motion by hair cell loss. Four days after ototoxic damage, we identified newly regenerated, nascent auditory hair cells that express genes linked to termination of the interferon response. These cells are incipient modified neurons that represent a population of hair cells en route towards obtaining their location-specific and fully functional cell identity. The robust, transient expression of immune-related genes in supporting cells suggests a potential functional involvement of JAK/STAT signaling and interferon in sensory hair cell regeneration.

scholarly journals Watching Death in the Gerbil Cochlea Using Optical Coherence Tomography (OCT)

2021 ◽  
Author(s):  
Nam Hyun Cho ◽  
Haobing Wang ◽  
Sunil Puria
Keyword(s):  
Optical Coherence Tomography ◽  
Hair Cell ◽  
Outer Hair Cell ◽  
Round Window ◽  
Fluid Pressure ◽  
Organ Of Corti ◽  
Round Window Membrane ◽  
Tectorial Membrane ◽  
Optical Coherence

Because it is difficult to directly observe the morphology of the living cochlea, our ability to infer the mechanical functioning of the living ear has been limited. Nearly all of our knowledge about cochlear morphology comes from postmortem tissue that was fixed and processed using procedures that possibly distort the structures and fluid spaces of the organ of Corti. In this study, optical coherence tomography was employed to obtain in vivo and postmortem micron-scale volumetric images of the high-frequency hook region of the gerbil cochlea through the round-window membrane. The anatomical structures and fluid spaces of the organ of Corti were segmented and quantified in vivo and over a 90-minute postmortem period. The results show that some aspects of the organ of Corti are significantly altered over the course of death, such as the volumes of the fluid spaces, whereas the dimensions of other features change very little. We postulate that the fluid space of the outer tunnel and its surrounding tectal cells form a resonant structure that can affect the motion of the reticular lamina and thereby have a profound effect on outer-hair-cell transduction and thus cochlear amplification. In addition, the in vivo fluid pressure of the inner spiral sulcus is postulated to effectively inflate the connected sub-tectorial gap between the tectorial membrane and the reticular lamina. This gap height decreases after death, which is hypothesized to reduce and disrupt hair-cell transduction.

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