Vestibular and Auditory Hair Cell Regeneration Following Targeted Ablation of Hair Cells With Diphtheria Toxin in Zebrafish
13
Citation
33
Reference
10
Related Paper
Citation Trend
Abstract:
Millions of Americans experience hearing or balance disorders due to loss of hair cells in the inner ear. The hair cells are mechanosensory receptors used in the auditory and vestibular organs of all vertebrates as well as the lateral line systems of aquatic vertebrates. In zebrafish and other non-mammalian vertebrates, hair cells turnover during homeostasis and regenerate completely after being destroyed or damaged by acoustic or chemical exposure. However, in mammals, destroying or damaging hair cells results in permanent impairments to hearing or balance. We sought an improved method for studying hair cell damage and regeneration in adult aquatic vertebrates by generating a transgenic zebrafish with the capacity for targeted and inducible hair cell ablation in vivo . This model expresses the human diphtheria toxin receptor (hDTR) gene under the control of the myo6b promoter, resulting in hDTR expressed only in hair cells. Cell ablation is achieved by an intraperitoneal injection of diphtheria toxin (DT) in adult zebrafish or DT dissolved in the water for larvae. In the lateral line of 5 days post fertilization (dpf) zebrafish, ablation of hair cells by DT treatment occurred within 2 days in a dose-dependent manner. Similarly, in adult utricles and saccules, a single intraperitoneal injection of 0.05 ng DT caused complete loss of hair cells in the utricle and saccule by 5 days post-injection. Full hair cell regeneration was observed for the lateral line and the inner ear tissues. This study introduces a new method for efficient conditional hair cell ablation in adult zebrafish inner ear sensory epithelia (utricles and saccules) and demonstrates that zebrafish hair cells will regenerate in vivo after this treatment.Keywords:
Utricle
Ototoxicity
Otic vesicle
Diphtheria Toxin
Utricle
Cell type
Cite
Citations (25)
Ototoxicity
Cite
Citations (188)
Ototoxicity
Neomycin
Stereocilia (inner ear)
Cite
Citations (3)
Utricle
Ototoxicity
Saccule
Cite
Citations (149)
Cisplatin is a chemotherapeutic agent that is widely used in the treatment of solid tumors. Ototoxicity is a common side effect of cisplatin therapy and often leads to permanent hearing loss. The sensory organs of the avian ear are able to regenerate hair cells after aminoglycoside ototoxicity. This regenerative response is mediated by supporting cells, which serve as precursors to replacement hair cells. Given the antimitotic properties of cisplatin, we examined whether the avian ear was also capable of regeneration after cisplatin ototoxicity. Using cell and organ cultures of the chick cochlea and utricle, we found that cisplatin treatment caused apoptosis of both auditory and vestibular hair cells. Hair cell death in the cochlea occurred in a unique pattern, progressing from the low-frequency (distal) region toward the high-frequency (proximal) region. We also found that cisplatin caused a dose-dependent reduction in the proliferation of cultured supporting cells as well as increased apoptosis in those cells. As a result, we observed no recovery of hair cells after ototoxic injury caused by cisplatin. Finally, we explored the potential for nonmitotic hair cell recovery via activation of Notch pathway signaling. Treatment with the γ-secretase inhibitor N -[ N -(3,5-difluorophenacetyl)- l -alanyl]- S -phenylglycine t -butyl ester failed to promote the direct transdifferentiation of supporting cells into hair cells in cisplatin-treated utricles. Taken together, our data show that cisplatin treatment causes maintained changes to inner ear supporting cells and severely impairs the ability of the avian ear to regenerate either via proliferation or by direct transdifferentiation.
Ototoxicity
Transdifferentiation
Cite
Citations (43)
Cisplatin is a chemotherapeutic agent that is widely used in the treatment of solid tumors. Ototoxicity is a common side effect of cisplatin therapy and often leads to permanent hearing loss. The sensory organs of the avian ear are able to regenerate hair cells after aminoglycoside ototoxicity. This regenerative response is mediated by supporting cells, which serve as precursors to replacement hair cells. Given the antimitotic properties of cisplatin, we examined whether the avian ear was also capable of regeneration after cisplatin ototoxicity. Using cell and organ cultures of the chick cochlea and utricle, we found that cisplatin treatment caused apoptosis of both auditory and vestibular hair cells. Hair cell death in the cochlea occurred in a unique pattern, progressing from the low-frequency (distal) region toward the high-frequency (proximal) region. We also found that cisplatin caused a dose-dependent reduction in the proliferation of cultured supporting cells as well as increased apoptosis in those cells. As a result, we observed no recovery of hair cells after ototoxic injury caused by cisplatin. Finally, we explored the potential for nonmitotic hair cell recovery via activation of Notch pathway signaling. Treatment with the γ-secretase inhibitor N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butyl ester failed to promote the direct transdifferentiation of supporting cells into hair cells in cisplatin-treated utricles. Taken together, our data show that cisplatin treatment causes maintained changes to inner ear supporting cells and severely impairs the ability of the avian ear to regenerate either via proliferation or by direct transdifferentiation.
Ototoxicity
Transdifferentiation
Cite
Citations (9)
Ototoxicity
Auditory brainstem response
Otoacoustic emission
Cite
Citations (64)
The Mongolian gerbil, Meriones unguiculatus, has been widely employed as a model for studies of the inner ear. In spite of its established use for auditory research, no robust protocols to induce ototoxic hair cell damage have been developed for this species. In this paper, we demonstrate the development of an aminoglycoside-induced model of hair cell loss, using kanamycin potentiated by the loop diuretic furosemide. Interestingly, we show that the gerbil is relatively insensitive to gentamicin compared to kanamycin, and that bumetanide is ineffective in potentiating the ototoxicity of the drug. We also examine the pathology of the spiral ganglion after chronic, long-term hair cell damage. Remarkably, there is little or no neuronal loss following the ototoxic insult, even at 8 months post-damage. This is similar to the situation often seen in the human, where functioning neurons can persist even decades after hair cell loss, contrasting with the rapid, secondary degeneration found in rats, mice and other small mammals. We propose that the combination of these factors makes the gerbil a good model for ototoxic damage by induced hair cell loss.
Gerbil
Ototoxicity
Spiral ganglion
Kanamycin
Cite
Citations (38)
Influence of 24-diamino-5-phenylthiazole on neomycin ototoxicity in cultured organ of Corti explants
Hair cells do not undergo spontaneous regeneration when they are damaged in the mammalian organ of Corti, leading to irreversible hearing loss. Previous studies have shown that 24-diamino-5-phenylthiazole (DAPT), an inhibitor of Notch signaling, plays a major role in inner ear development. However, whether DAPT influences antibiotic-induced hair cell damage remains uncertain. The present study aimed to investigate whether DAPT exerts protective or regenerative effects on neomycin-damaged hair cells. A histological analysis was carried out to assess the number and morphological changes of hair cells in cultured organ of Corti explants. Our results showed that in-vitro treatment with DAPT induced extra hair cells, whereas no newly generated supporting cells were found. We also found that DAPT was effective for preventing hair cell loss when cotreatment with neomycin was performed, suggesting that DAPT exerted protective effects on neomycin ototoxicity. In addition, DAPT treatment for 2–4 days following neomycin damage induced supernumerary hair cells. These findings indicate that inhibition of Notch signaling is a possible strategy for the treatment of hair cell loss caused by aminoglycoside antibiotics.
Neomycin
Ototoxicity
Cite
Citations (1)
Aminoglycosides are highly effective antibiotics; however, their clinical utility is severely limited by their nephrotoxic and ototoxic side-effects. The selective destruction of hair cells in the inner ear by aminoglycoside antibiotics is thought to arise from a carefully orchestrated programme of cell death involving caspases and calcium activated proteases or calpains. To more fully evaluate the role of calpains in aminoglycoside ototoxicity, we applied the cell permeant, selective calpain inhibitor MDL 28170, to gentamicin (GM) treated cochlear organotypic cultures and evaluated the degree of hair cell damage at various drug concentrations. Mean hair cell losses in cochlear cultures treated for 24hours with 250, 500 and 1000 μM of GM were 17, 64 and 81%, respectively. Cochlear cultures treated with 200 μM of MDL 28170 alone for 24hours had no adverse effects on hair cell survival. However, the two highest doses of MDL 28170 (500 and 1000 μM) resulted in disorganization of hair cell rows, stereocilia damage and 30–35% hair cell loss. Addition of MDL 28170 to cochlear cultures treated with 500 and 1000 μM GM enhanced hair cell survival in a dose-dependent manner. Two hundred μM of MDL 28170, which by itself had no adverse effects on hair cells survival, significantly enhanced hair cell survival (30–35%), but failed to provide complete protection against GM ototoxicity. Since MDL 28170 can cross the blood-brain barrier and prevent neurodegeneration, it could conceivably be used in vivo to attenuate aminoglycoside ototoxicity.
Ototoxicity
Stereocilia (inner ear)
Cite
Citations (9)