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Majdi JA, Qian H, Li Y, Langsner RJ, Shea KI, Agrawal A, Hammer DX, Hanig JP, Cohen ED. The use of time-lapse optical coherence tomography to image the effects of microapplied toxins on the retina. Invest Ophthalmol Vis Sci 2014; 56:587-97. [PMID: 25525175 DOI: 10.1167/iovs.14-15594] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE We developed a novel technique for accelerated drug screening and retinotoxin characterization using time-lapse optical coherence tomography (OCT) and a drug microapplication device. METHODS Using an ex vivo rabbit eyecup preparation, we studied retinotoxin effects in real-time by microperfusing small retinal areas under a transparent fluoropolymer tube. Known retinotoxic agents were applied to the retina for 5-minute periods, while changes in retinal structure, thickness, and reflectance were monitored with OCT. The OCT images of two agents with dissimilar mechanisms, cyanide and kainic acid, were compared to their structural changes seen histologically. RESULTS We found the actions of retinotoxic agents tested could be classified broadly into two distinct types: (1) agents that induce neuronal depolarization, such as kainic acid, causing increases in OCT reflectivity or thickness of the inner plexiform and nuclear layers, and decreased reflectivity of the outer retina; and (2) agents that disrupt mitochondrial function, such as cyanide, causing outer retinal structural changes as evidenced by a reduction in the OCT reflectivity of the photoreceptor outer segment and pigment epithelium layers. CONCLUSIONS Retinotoxin-induced changes in retinal layer reflectivity and thickness under the microperfusion tube in OCT images closely matched the histological evidence of retinal injury. Time-lapse OCT imaging of the microperfused local retina has the potential to accelerate drug retinotoxicological screening and expand the use of OCT as an evaluation tool for preclinical animal testing.
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Affiliation(s)
- Joseph A Majdi
- Division of Biomedical Physics, Office of Science and Engineering Labs, Center for Devices and Radiological Health, Food and Drug Administration, White Oak Federal Research Labs, Silver Spring, Maryland, United States
| | - Haohua Qian
- National Eye Institute, Visual Function Core, National Institutes of Health, Bethesda, Maryland, United States
| | - Yichao Li
- National Eye Institute, Visual Function Core, National Institutes of Health, Bethesda, Maryland, United States
| | - Robert J Langsner
- Division of Biomedical Physics, Office of Science and Engineering Labs, Center for Devices and Radiological Health, Food and Drug Administration, White Oak Federal Research Labs, Silver Spring, Maryland, United States
| | - Katherine I Shea
- Office of Testing and Research, Center for Drug Evaluation and Research, Food and Drug Administration, White Oak Federal Research Labs, Silver Spring, Maryland, United States
| | - Anant Agrawal
- Division of Biomedical Physics, Office of Science and Engineering Labs, Center for Devices and Radiological Health, Food and Drug Administration, White Oak Federal Research Labs, Silver Spring, Maryland, United States
| | - Daniel X Hammer
- Division of Biomedical Physics, Office of Science and Engineering Labs, Center for Devices and Radiological Health, Food and Drug Administration, White Oak Federal Research Labs, Silver Spring, Maryland, United States
| | - Joseph P Hanig
- Office of Testing and Research, Center for Drug Evaluation and Research, Food and Drug Administration, White Oak Federal Research Labs, Silver Spring, Maryland, United States
| | - Ethan D Cohen
- Division of Biomedical Physics, Office of Science and Engineering Labs, Center for Devices and Radiological Health, Food and Drug Administration, White Oak Federal Research Labs, Silver Spring, Maryland, United States
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Slattery EL, Oshima K, Heller S, Warchol ME. Cisplatin exposure damages resident stem cells of the mammalian inner ear. Dev Dyn 2014; 243:1328-37. [PMID: 24888499 DOI: 10.1002/dvdy.24150] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2014] [Revised: 04/29/2014] [Accepted: 05/10/2014] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Cisplatin is a widely used chemotherapeutic agent that can also cause ototoxic injury. One potential treatment for cisplatin-induced hearing loss involves the activation of endogenous inner ear stem cells, which may then produce replacement hair cells. In this series of experiments, we examined the effects of cisplatin exposure on both hair cells and resident stem cells of the mouse inner ear. RESULTS Treatment for 24 hr with 10 µM cisplatin caused significant loss of hair cells in the mouse utricle, but such damage was not evident until 4 days after the cisplatin exposure. In addition to killing hair cells, cisplatin treatment also disrupted the actin cytoskeleton in remaining supporting cells, and led to increased histone H2AX phosphorylation within the sensory epithelia. Finally, treatment with 10 µM cisplatin appeared to have direct toxic effects on resident stem cells in the mouse utricle. Exposure to cisplatin blocked the proliferation of isolated stem cells and prevented sphere formation when those cells were maintained in suspension culture. CONCLUSION The results suggest that inner ear stem cells may be injured during cisplatin ototoxicity, thus limiting their ability to mediate sensory repair.
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Affiliation(s)
- Eric L Slattery
- Department of Otolaryngology, Washington University School of Medicine, Saint Louis, Missouri
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Barrett D, Yang J, Sujirakul T, Tsang SH. Vigabatrin Retinal Toxicity First Detected with Electroretinographic Changes: A Case Report. ACTA ACUST UNITED AC 2014; 5. [PMID: 26295007 DOI: 10.4172/2155-9570.1000363] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Vigabatrin is an effective antiepileptic drug (AED) typically used in the treatment of refractory partial seizures and infantile spasms. Its use, however, is limited due to the concern of retinal toxicity and subsequent visual field defects. Herewith in we describe a case of vigabatrin toxicity that illustrates electroretinographic (ERG) changes occur before imaging and visual field deterioration. Decrease in maximal ERG b: a ratio was observed before thinning of the retinal nerve fiber layer (RNFL) on optical coherence tomography (OCT).
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Affiliation(s)
- Dianne Barrett
- College of Physicians & Surgeons, Columbia University, New York, NY 10032, USA
| | - Jin Yang
- Edward S. Harkness Eye Institute, Columbia University, New York, NY 10032, USA
| | - Tharikarn Sujirakul
- Edward S. Harkness Eye Institute, Columbia University, New York, NY 10032, USA
| | - Stephen H Tsang
- Edward S. Harkness Eye Institute, Columbia University, New York, NY 10032, USA ; Bernard & Shirlee Brown Glaucoma Laboratory, Departments of Ophthalmology, Pathology & Cell Biology, Columbia University, New York, NY 10032, USA ; New York-Presbyterian Hospital/Columbia University Medical Center, New York, NY 10032, USA
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Disruption of intracellular calcium regulation is integral to aminoglycoside-induced hair cell death. J Neurosci 2013; 33:7513-25. [PMID: 23616556 DOI: 10.1523/jneurosci.4559-12.2013] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Intracellular Ca(2+) is a key regulator of life or death decisions in cultured neurons and sensory cells. The role of Ca(2+) in these processes is less clear in vivo, as the location of these cells often impedes visualization of intracellular Ca(2+) dynamics. We generated transgenic zebrafish lines that express the genetically encoded Ca(2+) indicator GCaMP in mechanosensory hair cells of the lateral line. These lines allow us to monitor intracellular Ca(2+) dynamics in real time during aminoglycoside-induced hair cell death. After exposure of live larvae to aminoglycosides, dying hair cells undergo a transient increase in intracellular Ca(2+) that occurs shortly after mitochondrial membrane potential collapse. Inhibition of intracellular Ca(2+) elevation through either caged chelators or pharmacological inhibitors of Ca(2+) effectors mitigates toxic effects of aminoglycoside exposure. Conversely, artificial elevation of intracellular Ca(2+) by caged Ca(2+) release agents sensitizes hair cells to the toxic effects of aminoglycosides. These data suggest that alterations in intracellular Ca(2+) homeostasis play an essential role in aminoglycoside-induced hair cell death, and indicate several potential therapeutic targets to stem ototoxicity.
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