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Lue PY, Oliver MH, Neeff M, Thorne PR, Suzuki-Kerr H. Sheep as a large animal model for hearing research: comparison to common laboratory animals and humans. Lab Anim Res 2023; 39:31. [PMID: 38012676 PMCID: PMC10680324 DOI: 10.1186/s42826-023-00182-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 11/10/2023] [Accepted: 11/15/2023] [Indexed: 11/29/2023] Open
Abstract
Sensorineural hearing loss (SNHL), caused by pathology in the cochlea, is the most common type of hearing loss in humans. It is generally irreversible with very few effective pharmacological treatments available to prevent the degenerative changes or minimise the impact. Part of this has been attributed to difficulty of translating "proof-of-concept" for novel treatments established in small animal models to human therapies. There is an increasing interest in the use of sheep as a large animal model. In this article, we review the small and large animal models used in pre-clinical hearing research such as mice, rats, chinchilla, guinea pig, rabbit, cat, monkey, dog, pig, and sheep to humans, and compare the physiology, inner ear anatomy, and some of their use as model systems for SNHL, including cochlear implantation surgeries. Sheep have similar cochlear anatomy, auditory threshold, neonatal auditory system development, adult and infant body size, and number of birth as humans. Based on these comparisons, we suggest that sheep are well-suited as a potential translational animal model that bridges the gap between rodent model research to the clinical use in humans. This is especially in areas looking at changes across the life-course or in specific areas of experimental investigation such as cochlear implantation and other surgical procedures, biomedical device development and age-related sensorineural hearing loss research. Combined use of small animals for research that require higher throughput and genetic modification and large animals for medical translation could greatly accelerate the overall translation of basic research in the field of auditory neuroscience from bench to clinic.
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Affiliation(s)
- Po-Yi Lue
- Department of Physiology, The University of Auckland, Auckland, New Zealand
- Eisdell Moore Centre, The University of Auckland, Auckland, New Zealand
| | - Mark H Oliver
- Liggins Institute, The University of Auckland, Auckland, New Zealand
- Ngapouri Research Farm Laboratory, University of Auckland, Waiotapu, New Zealand
| | - Michel Neeff
- Department of Physiology, The University of Auckland, Auckland, New Zealand
- Department of Surgery, Auckland District Health Board, Auckland, New Zealand
| | - Peter R Thorne
- Department of Physiology, The University of Auckland, Auckland, New Zealand
- Eisdell Moore Centre, The University of Auckland, Auckland, New Zealand
- Section of Audiology, The University of Auckland, Auckland, New Zealand
| | - Haruna Suzuki-Kerr
- Department of Physiology, The University of Auckland, Auckland, New Zealand.
- Eisdell Moore Centre, The University of Auckland, Auckland, New Zealand.
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2
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Dual Drug Delivery in Cochlear Implants: In Vivo Study of Dexamethasone Combined with Diclofenac or Immunophilin Inhibitor MM284 in Guinea Pigs. Pharmaceutics 2023; 15:pharmaceutics15030726. [PMID: 36986587 PMCID: PMC10058822 DOI: 10.3390/pharmaceutics15030726] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Revised: 02/20/2023] [Accepted: 02/21/2023] [Indexed: 02/24/2023] Open
Abstract
Cochlear implants are well established to treat severe hearing impairments. Despite many different approaches to reduce the formation of connective tissue after electrode insertion and to keep electrical impedances low, results are not yet satisfying. Therefore, the aim of the current study was to combine the incorporation of 5% dexamethasone in the silicone body of the electrode array with an additional polymeric coating releasing diclofenac or the immunophilin inhibitor MM284, some anti-inflammatory substances not yet tested in the inner ear. Guinea pigs were implanted for four weeks and hearing thresholds were determined before implantation and after the observation time. Impedances were monitored over time and, finally, connective tissue and the survival of spiral ganglion neurons (SGNs) were quantified. Impedances increased in all groups to a similar extent but this increase was delayed in the groups with an additional release of diclofenac or MM284. Using Poly-L-lactide (PLLA)-coated electrodes, the damage caused during insertion was much higher than without the coating. Only in these groups, connective tissue could extend to the apex of the cochlea. Despite this, numbers of SGNs were only reduced in PLLA and PLLA plus diclofenac groups. Even though the polymeric coating was not flexible enough, MM284 seems to especially have potential for further evaluation in connection with cochlear implantation.
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3
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Urata S, Okabe S. Three-dimensional mouse cochlea imaging based on the modified Sca/eS using confocal microscopy. Anat Sci Int 2023:10.1007/s12565-023-00703-z. [PMID: 36773194 DOI: 10.1007/s12565-023-00703-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 01/13/2023] [Indexed: 02/12/2023]
Abstract
The three-dimensional stria vascularis (SV) and cochlear blood vessel structure is essential for inner ear function. Here, modified Sca/eS, a sorbitol-based optical-clearing method, was reported to visualize SV and vascular structure in the intact mouse cochlea. Cochlear macrophages as well as perivascular-resident macrophage-like melanocytes were detected as GFP-positive cells of the CX3CR1+/GFP mice. This study's method was effective in elucidating inner ear function under both physiological and pathological conditions.
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Affiliation(s)
- Shinji Urata
- Department of Otolaryngology, Graduate School of Medicine, University of Tokyo, Tokyo, 113-0033, Japan.
| | - Shigeo Okabe
- Department of Cellular Neurobiology, Graduate School of Medicine, the University of Tokyo, Tokyo, Japan
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4
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Toulemonde P, Risoud M, Lemesre PE, Beck C, Wattelet J, Tardivel M, Siepmann J, Vincent C. Evaluation of the Efficacy of Dexamethasone-Eluting Electrode Array on the Post-Implant Cochlear Fibrotic Reaction by Three-Dimensional Immunofluorescence Analysis in Mongolian Gerbil Cochlea. J Clin Med 2021; 10:jcm10153315. [PMID: 34362099 PMCID: PMC8347204 DOI: 10.3390/jcm10153315] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 07/22/2021] [Accepted: 07/26/2021] [Indexed: 11/16/2022] Open
Abstract
Cochlear implant is the method of choice for the rehabilitation of severe to profound sensorineural hearing loss. The study of the tissue response to cochlear implantation and the prevention of post-cochlear-implant damages are areas of interest in hearing protection research. The objective was to assess the efficacy of dexamethasone-eluting electrode array on endo canal fibrosis formation by three-dimensional immunofluorescence analysis in implanted Mongolian gerbil cochlea. Two trials were conducted after surgery using Mongolian gerbil implanted with dexamethasone-eluting or non-eluting intracochlear electrode arrays. The animals were then euthanised 10 weeks after implantation. The cochleae were prepared (electrode array in place) according to a 29-day protocol with immunofluorescent labelling and tissue clearing. The acquisition was carried out using light-sheet microscopy. Imaris software was then used for three-dimensional analysis of the cochleae and quantification of the fibrotic volume. The analysis of 12 cochleae showed a significantly different mean volume of fibrosis (2.16 × 108 μm3 ± 0.15 in the dexamethasone eluting group versus 3.17 × 108 μm3 ± 0.54 in the non-eluting group) (p = 0.004). The cochlear implant used as a corticosteroid delivery system appears to be an encouraging device for the protection of the inner ear against fibrosis induced by implantation. Three-dimensional analysis of the cochlea by light-sheet microscopy was suitable for studying post-implantation tissue damage.
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Affiliation(s)
- Philippine Toulemonde
- Department of Otology and Neurotology, CHU Lille, University of Lille 2 Henri Warembourg, F-59000 Lille, France; (M.R.); (P.E.L.); (C.B.); (J.W.); (J.S.); (C.V.)
- INSERM U1008—Controlled Drug Delivery Systems and Biomaterials, F-59000 Lille, France
- Correspondence: ; Tel.: +33-6851-91052
| | - Michaël Risoud
- Department of Otology and Neurotology, CHU Lille, University of Lille 2 Henri Warembourg, F-59000 Lille, France; (M.R.); (P.E.L.); (C.B.); (J.W.); (J.S.); (C.V.)
- INSERM U1008—Controlled Drug Delivery Systems and Biomaterials, F-59000 Lille, France
| | - Pierre Emmanuel Lemesre
- Department of Otology and Neurotology, CHU Lille, University of Lille 2 Henri Warembourg, F-59000 Lille, France; (M.R.); (P.E.L.); (C.B.); (J.W.); (J.S.); (C.V.)
- INSERM U1008—Controlled Drug Delivery Systems and Biomaterials, F-59000 Lille, France
| | - Cyril Beck
- Department of Otology and Neurotology, CHU Lille, University of Lille 2 Henri Warembourg, F-59000 Lille, France; (M.R.); (P.E.L.); (C.B.); (J.W.); (J.S.); (C.V.)
- INSERM U1008—Controlled Drug Delivery Systems and Biomaterials, F-59000 Lille, France
| | - Jean Wattelet
- Department of Otology and Neurotology, CHU Lille, University of Lille 2 Henri Warembourg, F-59000 Lille, France; (M.R.); (P.E.L.); (C.B.); (J.W.); (J.S.); (C.V.)
- INSERM U1008—Controlled Drug Delivery Systems and Biomaterials, F-59000 Lille, France
| | - Meryem Tardivel
- BioImaging Center Lille-Nord de France (BICeL), University of Lille 2 Henri Warembourg, F-59000 Lille, France;
| | - Juergen Siepmann
- Department of Otology and Neurotology, CHU Lille, University of Lille 2 Henri Warembourg, F-59000 Lille, France; (M.R.); (P.E.L.); (C.B.); (J.W.); (J.S.); (C.V.)
- INSERM U1008—Controlled Drug Delivery Systems and Biomaterials, F-59000 Lille, France
| | - Christophe Vincent
- Department of Otology and Neurotology, CHU Lille, University of Lille 2 Henri Warembourg, F-59000 Lille, France; (M.R.); (P.E.L.); (C.B.); (J.W.); (J.S.); (C.V.)
- INSERM U1008—Controlled Drug Delivery Systems and Biomaterials, F-59000 Lille, France
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5
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In Situ 3D-Imaging of the Inner Ear Synapses with a Cochlear Implant. Life (Basel) 2021; 11:life11040301. [PMID: 33915846 PMCID: PMC8066088 DOI: 10.3390/life11040301] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 03/27/2021] [Accepted: 03/28/2021] [Indexed: 11/17/2022] Open
Abstract
In recent years sensorineural hearing loss was found to affect not exclusively, nor at first, the sensory cells of the inner ear. The sensory cells' synapses and subsequent neurites are initially damaged. Auditory synaptopathies also play an important role in cochlear implant (CI) care, as they can lead to a loss of physiological hearing in patients with residual hearing. These auditory synaptopathies and in general the cascades of hearing pathologies have been in the focus of research in recent years with the aim to develop more targeted and individually tailored therapeutics. In the current study, a method to examine implanted inner ears of guinea pigs was developed to examine the synapse level. For this purpose, the cochlea is made transparent and scanned with the implant in situ using confocal laser scanning microscopy. Three different preparation methods were compared to enable both an overview image of the cochlea for assessing the CI position and images of the synapses on the same specimen. The best results were achieved by dissection of the bony capsule of the cochlea.
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Zu M, Guo WW, Cong T, Ji F, Zhang SL, Zhang Y, Song X, Sun W, He DZZ, Shi WG, Yang SM. SCN11A gene deletion causes sensorineural hearing loss by impairing the ribbon synapses and auditory nerves. BMC Neurosci 2021; 22:18. [PMID: 33752606 PMCID: PMC7986359 DOI: 10.1186/s12868-021-00613-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 01/20/2021] [Indexed: 11/10/2022] Open
Abstract
Background The SCN11A gene, encoded Nav1.9 TTX resistant sodium channels, is a main effector in peripheral inflammation related pain in nociceptive neurons. The role of SCN11A gene in the auditory system has not been well characterized. We therefore examined the expression of SCN11A in the murine cochlea, the morphological and physiological features of Nav1.9 knockout (KO) ICR mice. Results Nav1.9 expression was found in the primary afferent endings beneath the inner hair cells (IHCs). The relative quantitative expression of Nav1.9 mRNA in modiolus of wild-type (WT) mice remains unchanged from P0 to P60. The number of presynaptic CtBP2 puncta in Nav1.9 KO mice was significantly lower than WT. In addition, the number of SGNs in Nav1.9 KO mice was also less than WT in the basal turn, but not in the apical and middle turns. There was no lesion in the somas and stereocilia of hair cells in Nav1.9 KO mice. Furthermore, Nav1.9 KO mice showed higher and progressive elevated ABR threshold at 16 kHz, and a significant increase in CAP thresholds. Conclusions These data suggest a role of Nav1.9 in regulating the function of ribbon synapses and the auditory nerves. The impairment induced by Nav1.9 gene deletion mimics the characters of cochlear synaptopathy.
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Affiliation(s)
- Mian Zu
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,Key Lab of Hearing Science, Ministry of Education, Beijing, China.,Beijing Key Lab of Hearing Impairment for Prevention and Treatment, Beijing, China
| | - Wei-Wei Guo
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,Key Lab of Hearing Science, Ministry of Education, Beijing, China.,Beijing Key Lab of Hearing Impairment for Prevention and Treatment, Beijing, China
| | - Tao Cong
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,Key Lab of Hearing Science, Ministry of Education, Beijing, China.,Beijing Key Lab of Hearing Impairment for Prevention and Treatment, Beijing, China
| | - Fei Ji
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,Key Lab of Hearing Science, Ministry of Education, Beijing, China.,Beijing Key Lab of Hearing Impairment for Prevention and Treatment, Beijing, China
| | - Shi-Li Zhang
- Clinical Hearing Center of Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, China
| | - Yue Zhang
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,Key Lab of Hearing Science, Ministry of Education, Beijing, China.,Beijing Key Lab of Hearing Impairment for Prevention and Treatment, Beijing, China
| | - Xin Song
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,Key Lab of Hearing Science, Ministry of Education, Beijing, China.,Beijing Key Lab of Hearing Impairment for Prevention and Treatment, Beijing, China
| | - Wei Sun
- Department of Communicative Disorders and Sciences, Center for Hearing and Deafness, The State University of New York at Buffalo, Buffalo, NY, USA
| | - David Z Z He
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, NE, 68178, USA
| | - Wei-Guo Shi
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing, China.
| | - Shi-Ming Yang
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Beijing, China. .,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China. .,Key Lab of Hearing Science, Ministry of Education, Beijing, China. .,Beijing Key Lab of Hearing Impairment for Prevention and Treatment, Beijing, China.
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7
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Konerding W, Arenberg JG, Kral A, Baumhoff P. Late electrically-evoked compound action potentials as markers for acute micro-lesions of spiral ganglion neurons. Hear Res 2020; 413:108057. [PMID: 32883545 DOI: 10.1016/j.heares.2020.108057] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 07/13/2020] [Accepted: 08/11/2020] [Indexed: 12/20/2022]
Abstract
Cochlear implants (CIs) are the treatment of choice for profoundly hearing impaired people. It has been proposed that speech perception in CI users is influenced by the neural health (deafferentation, demyelination and degeneration) of the cochlea, which may be heterogeneous along an individual cochlea. Several options have been put forward to account for these local differences in neural health when fitting the speech processor settings, however with mixed results. The interpretation of the results is hampered by the fact that reliable markers of locally restricted changes in spiral ganglion neuron (SGN) health are lacking. The aim of the study was (i) to establish mechanical micro-lesions in the guinea pig as a model of heterogeneous SGN deafferentation and degeneration and (ii) to assess potential electrophysiological markers that can also be used in human subjects. First, we defined the extent of micro-lesions in normal hearing animals using acoustically-evoked compound action potentials (aCAPs); second, we measured electrically-evoked CAPs (eCAPs) before and after focal lesioning in neomycin-deafened and implanted animals. Therefore, we inserted guinea pig adjusted 6-contact CIs through a cochleostomy in the scala tympani. The eCAP was recorded from a ball electrode at the round window niche in response to monopolar or bipolar, 50 µs/phase biphasic pulses of alternating anodic- and cathodic-leading polarity. To exclude the large electrical artifact from the analysis, we focused on the late eCAP component. We systematically isolated the eCAP parameter that showed local pre- versus post-lesion changes and lesion-target specificity. Histological evaluation of the cleared cochleae revealed focal damage of an average size of 0.0036 mm3 with an apical-basal span of maximal 440 µm. We found that the threshold of the late N2P2 eCAP component was significantly elevated after lesioning when stimulating at basal (near the lesion), but not apical (distant to the lesion) CI contacts. To circumvent the potentially conflicting influence of the apical-basal gradient in eCAP thresholds, we used the polarity effect (PE=cathodic-anodic) as a relative measure. During monopolar stimulation, but not bipolar stimulation, the PE was sensitive to the lesion target and showed significantly better cathodic than anodic thresholds after soma lesions. We conclude that the difference in N2P2 thresholds in response to cathodic versus anodic-leading monopolar stimulation corresponds to the presence of SGN soma damage, and may therefore be a marker for SGN loss. We consider this electrophysiological estimate of local neural health a potentially relevant tool for human applications because of the temporal separation from the stimulation artifact and possible implementation into common eCAP measurements.
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Affiliation(s)
- Wiebke Konerding
- Department of Experimental Otology, Hannover Medical School, Stadtfelddamm 34, 30625 Hannover, Germany.
| | - Julie G Arenberg
- Massachusetts Eye and Ear Infirmary, Harvard Medical School, 25 Shattuck Street, Boston, MA 02115, USA.
| | - Andrej Kral
- Department of Experimental Otology, Hannover Medical School, Stadtfelddamm 34, 30625 Hannover, Germany; Cluster of Excellence "Hearing4all", Germany.
| | - Peter Baumhoff
- Department of Experimental Otology, Hannover Medical School, Stadtfelddamm 34, 30625 Hannover, Germany.
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8
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Hutson KA, Pulver SH, Ariel P, Naso C, Fitzpatrick DC. Light sheet microscopy of the gerbil cochlea. J Comp Neurol 2020; 529:757-785. [PMID: 32632959 DOI: 10.1002/cne.24977] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Revised: 05/13/2020] [Accepted: 06/21/2020] [Indexed: 01/19/2023]
Abstract
Light sheet fluorescence microscopy (LSFM) provides a rapid and complete three-dimensional image of the cochlea. The method retains anatomical relationships-on a micrometer scale-between internal structures such as hair cells, basilar membrane (BM), and modiolus with external surface structures such as the round and oval windows. Immunolabeled hair cells were used to visualize the spiraling BM in the intact cochlea without time intensive dissections or additional histological processing; yet material prepared for LSFM could be rehydrated, the BM dissected out and reimaged at higher resolution with the confocal microscope. In immersion-fixed material, details of the cochlear vasculature were seen throughout the cochlea. Hair cell counts (both inner and outer) as well as frequency maps of the BM were comparable to those obtained by other methods, but with the added dimension of depth. The material provided measures of angular, linear, and vector distance between characteristic frequency regions along the BM. Thus, LSFM provides a unique ability to rapidly image the entire cochlea in a manner applicable to model and interpret physiological results. Furthermore, the three-dimensional organization of the cochlea can be studied at the organ and cellular level with LSFM, and this same material can be taken to the confocal microscope for detailed analysis at the subcellular level.
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Affiliation(s)
- Kendall A Hutson
- Department of Otolaryngology/Head and Neck Surgery, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Stephen H Pulver
- Department of Otolaryngology/Head and Neck Surgery, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Pablo Ariel
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Caroline Naso
- Department of Otolaryngology/Head and Neck Surgery, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Douglas C Fitzpatrick
- Department of Otolaryngology/Head and Neck Surgery, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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9
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Simoni E, Gentilin E, Candito M, Borile G, Romanato F, Chicca M, Nordio S, Aspidistria M, Martini A, Cazzador D, Astolfi L. Immune Response After Cochlear Implantation. Front Neurol 2020; 11:341. [PMID: 32477241 PMCID: PMC7240074 DOI: 10.3389/fneur.2020.00341] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 04/07/2020] [Indexed: 12/20/2022] Open
Abstract
A cochlear implant (CI) is an electronic device that enables hearing recovery in patients with severe to profound hearing loss. Although CIs are a successful treatment for profound hearing impairment, their effectivity may be improved by reducing damages associated with insertion of electrodes in the cochlea, thus preserving residual hearing ability. Inner ear trauma leads to inflammatory reactions altering cochlear homeostasis and reducing post-operative audiological performances and electroacoustic stimulation. Strategies to preserve residual hearing ability led to the development of medicated devices to minimize CI-induced cochlear injury. Dexamethasone-eluting electrodes recently showed positive outcomes. In previous studies by our research group, intratympanic release of dexamethasone for 14 days was able to preserve residual hearing from CI insertion trauma in a Guinea pig model. Long-term effects of dexamethasone-eluting electrodes were therefore evaluated in the same animal model. Seven Guinea pigs were bilaterally implanted with medicated rods and four were implanted with non-eluting ones. Hearing threshold audiograms were acquired prior to implantation and up to 60 days by recording compound action potentials. For each sample, we examined the amount of bone and fibrous connective tissue grown within the scala tympani in the basal turn of the cochlea, the cochleostomy healing, the neuronal density, and the correlation between electrophysiological parameters and histological results. Detection of tumor necrosis factor alpha, interleukin-6, and foreign body giant cells showed that long-term electrode implantation was not associated with an ongoing inflammation. Growth of bone and fibrous connective tissue around rods induced by CI was reduced in the scala tympani by dexamethasone release. For cochleostomy sealing, dexamethasone-treated animals showed less bone tissue growth than negative. Dexamethasone did not affect cell density in the spiral ganglion. Overall, these results support the use of dexamethasone as anti-inflammatory additive for eluting electrodes able to protect the cochlea from CI insertion trauma.
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Affiliation(s)
- Edi Simoni
- Bioacoustics Research Laboratory, Department of Neurosciences, University of Padua, Padua, Italy.,Otorhinolaryngology Unit, Department of Neurosciences, University of Padua, Padua, Italy.,Section of Human Anatomy, Department of Neuroscience, University of Padua, Padua, Italy
| | - Erica Gentilin
- Bioacoustics Research Laboratory, Department of Neurosciences, University of Padua, Padua, Italy.,Otorhinolaryngology Unit, Department of Neurosciences, University of Padua, Padua, Italy
| | - Mariarita Candito
- Bioacoustics Research Laboratory, Department of Neurosciences, University of Padua, Padua, Italy.,Otorhinolaryngology Unit, Department of Neurosciences, University of Padua, Padua, Italy
| | - Giulia Borile
- Department of Physics and Astronomy "G. Galilei", University of Padua, Padua, Italy.,Laboratory for Nanofabrication of Nanodevices, Padua, Italy
| | - Filippo Romanato
- Department of Physics and Astronomy "G. Galilei", University of Padua, Padua, Italy.,Laboratory for Nanofabrication of Nanodevices, Padua, Italy
| | - Milvia Chicca
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - Sara Nordio
- Fondazione Ospedale San Camillo IRCCS, Venice, Italy
| | - Marta Aspidistria
- Department of Statistical Sciences, University of Padua, Padova, Italy
| | - Alessandro Martini
- Bioacoustics Research Laboratory, Department of Neurosciences, University of Padua, Padua, Italy.,Otorhinolaryngology Unit, Department of Neurosciences, University of Padua, Padua, Italy
| | - Diego Cazzador
- Bioacoustics Research Laboratory, Department of Neurosciences, University of Padua, Padua, Italy.,Otorhinolaryngology Unit, Department of Neurosciences, University of Padua, Padua, Italy.,Section of Human Anatomy, Department of Neuroscience, University of Padua, Padua, Italy
| | - Laura Astolfi
- Bioacoustics Research Laboratory, Department of Neurosciences, University of Padua, Padua, Italy.,Otorhinolaryngology Unit, Department of Neurosciences, University of Padua, Padua, Italy
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10
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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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11
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Scheper V, Hoffmann A, Gepp MM, Schulz A, Hamm A, Pannier C, Hubka P, Lenarz T, Schwieger J. Stem Cell Based Drug Delivery for Protection of Auditory Neurons in a Guinea Pig Model of Cochlear Implantation. Front Cell Neurosci 2019; 13:177. [PMID: 31139049 PMCID: PMC6527816 DOI: 10.3389/fncel.2019.00177] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 04/12/2019] [Indexed: 01/04/2023] Open
Abstract
Background: The success of a cochlear implant (CI), which is the standard therapy for patients suffering from severe to profound sensorineural hearing loss, depends on the number and excitability of spiral ganglion neurons (SGNs). Brain-derived neurotrophic factor (BDNF) has a protective effect on SGNs but should be applied chronically to guarantee their lifelong survival. Long-term administration of BDNF could be achieved using genetically modified mesenchymal stem cells (MSCs), but these cells should be protected – by ultra-high viscous (UHV-) alginate (‘alginate-MSCs’) – from the recipient immune system and from uncontrolled migration. Methods: Brain-derived neurotrophic factor-producing MSCs were encapsulated in UHV-alginate. Four experimental groups were investigated using guinea pigs as an animal model. Three of them were systemically deafened and (unilaterally) received one of the following: (I) a CI; (II) an alginate-MSC-coated CI; (III) an injection of alginate-embedded MSCs into the scala tympani followed by CI insertion and alginate polymerization. Group IV was normal hearing, with CI insertion in both ears and a unilateral injection of alginate-MSCs. Using acoustically evoked auditory brainstem response measurements, hearing thresholds were determined before implantation and before sacrificing the animals. Electrode impedance was measured weekly. Four weeks after implantation, the animals were sacrificed and the SGN density and degree of fibrosis were evaluated. Results: The MSCs survived being implanted for 4 weeks in vivo. Neither the alginate-MSC injection nor the coating affected electrode impedance or fibrosis. CI insertion with and without previous alginate injection in normal-hearing animals resulted in increased hearing thresholds within the high-frequency range. Low-frequency hearing loss was additionally observed in the alginate-injected and implanted cochleae, but not in those treated only with a CI. In deafened animals, the alginate-MSC coating of the CI significantly prevented SGN from degeneration, but the injection of alginate-MSCs did not. Conclusion: Brain-derived neurotrophic factor-producing MSCs encapsulated in UHV-alginate prevent SGNs from degeneration in the form of coating on the CI surface, but not in the form of an injection. No increase in fibrosis or impedance was detected. Further research and development aimed at verifying long-term mechanical and biological properties of coated electrodes in vitro and in vivo, in combination with chronic electrical stimulation, is needed before the current concept can be tested in clinical trials.
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Affiliation(s)
- Verena Scheper
- Department of Otolaryngology, Hannover Medical School, Hanover, Germany.,Cluster of Excellence 'Hearing4all', German Research Foundation, Bonn, Germany.,Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hanover, Germany
| | - Andrea Hoffmann
- Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hanover, Germany.,Department of Orthopaedic Surgery, Hannover Medical School, Hanover, Germany
| | - Michael M Gepp
- Fraunhofer Institute for Biomedical Engineering IBMT, Sulzbach, Germany.,Fraunhofer Project Center for Stem Cell Process Engineering, Würzburg, Germany
| | - André Schulz
- Fraunhofer Institute for Biomedical Engineering IBMT, Sulzbach, Germany
| | - Anika Hamm
- Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hanover, Germany.,Department of Orthopaedic Surgery, Hannover Medical School, Hanover, Germany
| | - Christoph Pannier
- Department of Otolaryngology, Hannover Medical School, Hanover, Germany
| | - Peter Hubka
- Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hanover, Germany.,Department of Experimental Otology, Hannover Medical School, Hanover, Germany
| | - Thomas Lenarz
- Department of Otolaryngology, Hannover Medical School, Hanover, Germany.,Cluster of Excellence 'Hearing4all', German Research Foundation, Bonn, Germany.,Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hanover, Germany
| | - Jana Schwieger
- Department of Otolaryngology, Hannover Medical School, Hanover, Germany.,Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hanover, Germany
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12
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Abstract
BACKGROUND In the field of hearing research a variety of imaging techniques are available to study molecular and cellular structures of the cochlea. Most of them are based on decalcifying, embedding, and cutting of the cochlea. By means of scanning laser optical tomography (SLOT), the complete cochlea can be visualized without cutting. The Cav1.3-/- mice have already been extensively characterized and show structural changes in the inner ear. Therefore, they were used in this study as a model to investigate whether SLOT can detect structural differences in the murine cochlea. MATERIALS AND METHODS Whole undissected cochleae from Cav1.3-/- and wild-type mice of various postnatal stages were immunostained and analyzed by SLOT. The results were compared to cochlea preparations that were immunostained and analyzed by fluorescence microscopy. In addition, cochlea preparations were stained with osmium tetraoxide. RESULTS Visualization by SLOT showed that the staining of nerve fibers at P27 in Cav1.3-/- mice was almost absent compared to wild-type mice and earlier timepoints (P9). The analysis of cochlea preparations confirmed a reduction of the radial nerve fibers. In addition, a significantly reduced number of ribbon synapses per inner hair cell (IHC) at P20 and P27 in the apical part of the cochlea of Cav1.3-/- mice was detected. CONCLUSION The visualization of whole non-dissected cochleae by SLOT is a suitable tool for the analysis of gross phenotypic changes, as demonstrated by means of the Cav1.3-/- mouse model. For the analysis of finer structures of the cochlea, however, further methods must be used.
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13
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[Scanning laser optical tomography in a neuropathic mouse model : Visualization of structural changes. German version]. HNO 2019; 67:590-599. [PMID: 30963223 DOI: 10.1007/s00106-019-0652-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
BACKGROUND In the field of hearing research a variety of imaging techniques are available to study molecular and cellular structures of the cochlea. Most of them are based on decalcifying, embedding, and cutting of the cochlea. By means of scanning laser optical tomography (SLOT), the complete cochlea can be visualized without cutting. The Cav1.3-/- mice have already been extensively characterized and show structural changes in the inner ear. Therefore, they were used in this study as a model to investigate whether SLOT can detect structural differences in the murine cochlea. MATERIALS AND METHODS Whole undissected cochleae from Cav1.3-/- and wildtype mice of various postnatal stages were immunostained and analyzed by SLOT. The results were compared to cochlea preparations that were immunostained and analyzed by fluorescence microscopy. In addition, cochlea preparations were stained with osmium tetraoxide. RESULTS Visualization by SLOT showed that the staining of nerve fibers at P27 in Cav1.3-/- mice was almost absent compared to wildtype mice and earlier timepoints (P9). The analysis of cochlea preparations confirmed a reduction of the radial nerve fibers. In addition, a significantly reduced number of ribbon synapses per inner hair cell (IHC) at P20 and P27 in the apical part of the cochlea of Cav1.3-/- mice was detected. CONCLUSION The visualization of whole non-dissected cochleae by SLOT is a suitable tool for the analysis of gross phenotypic changes, as demonstrated by means of the Cav1.3-/- mouse model. For the analysis of finer structures of the cochlea, however, further methods must be used.
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14
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Risoud M, Sircoglou J, Dedieu G, Tardivel M, Vincent C, Bonne NX. Imaging and cell count in cleared intact cochlea in the Mongolian gerbil using laser scanning confocal microscopy. Eur Ann Otorhinolaryngol Head Neck Dis 2017; 134:221-224. [DOI: 10.1016/j.anorl.2017.01.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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15
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Scheper V, Hessler R, Hütten M, Wilk M, Jolly C, Lenarz T, Paasche G. Local inner ear application of dexamethasone in cochlear implant models is safe for auditory neurons and increases the neuroprotective effect of chronic electrical stimulation. PLoS One 2017; 12:e0183820. [PMID: 28859106 PMCID: PMC5578571 DOI: 10.1371/journal.pone.0183820] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Accepted: 08/11/2017] [Indexed: 01/15/2023] Open
Abstract
Dexamethasone (DEX) can reduce fibrous tissue growth as well as loss of residual hearing which may occur after cochlear implantation. Little is known about the effect of local inner ear DEX treatment on the spiral ganglion neurons (SGN), which are the target of the electrical stimulation with a cochlear implant (CI). Three different clinically relevant strategies of DEX-delivery into the inner ear were used. DEX was either eluted from the electrode carriers' silicone, released from a reservoir by passive diffusion, or actively applied using a pump based system. The effect of the locally applied DEX on SGN density, size and function was evaluated. DEX did not affect the SGN density compared to the relevant control groups. Simultaneously applied with chronic electrical stimulation (ES), DEX increased the neuroprotective effect of ES in the basal region and the hearing threshold tended to decrease. The EABR thresholds did not correlate with the relevant SGN density. When correlating the SGN number with fibrosis, no dependency was observed. DEX concentrations as applied in these animal models are safe for inner ear delivery in terms of their effect on SGN density. Additionally, DEX tends to improve the neuroprotective effect of chronic electrical stimulation by increasing the number of surviving neurons. This is an important finding in regard to clinical applications of DEX for local treatment of the inner ear in view of cochlear implantation and other applications.
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Affiliation(s)
- Verena Scheper
- Hannover Medical School (MHH), Department of Otolaryngology, Hannover, Germany
- Cluster of Excellence Hearing4all, German Research Foundation, Hannover, Germany
- * E-mail:
| | - Roland Hessler
- MED-EL Innsbruck, Research & Development, Innsbruck, Österreich
| | - Mareike Hütten
- Hannover Medical School (MHH), Department of Otolaryngology, Hannover, Germany
| | - Maciej Wilk
- Hannover Medical School (MHH), Department of Otolaryngology, Hannover, Germany
| | - Claude Jolly
- MED-EL Innsbruck, Research & Development, Innsbruck, Österreich
| | - Thomas Lenarz
- Hannover Medical School (MHH), Department of Otolaryngology, Hannover, Germany
- Cluster of Excellence Hearing4all, German Research Foundation, Hannover, Germany
| | - Gerrit Paasche
- Hannover Medical School (MHH), Department of Otolaryngology, Hannover, Germany
- Cluster of Excellence Hearing4all, German Research Foundation, Hannover, Germany
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16
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Gutierre RC, Vannucci Campos D, Mortara RA, Coppi AA, Arida RM. Reflection imaging of China ink-perfused brain vasculature using confocal laser-scanning microscopy after clarification of brain tissue by the Spalteholz method. J Anat 2017; 230:601-606. [PMID: 28054714 DOI: 10.1111/joa.12578] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/15/2016] [Indexed: 11/28/2022] Open
Abstract
Confocal laser-scanning microscopy is a useful tool for visualizing neurons and glia in transparent preparations of brain tissue from laboratory animals. Currently, imaging capillaries and venules in transparent brain tissues requires the use of fluorescent proteins. Here, we show that vessels can be imaged by confocal laser-scanning microscopy in transparent cortical, hippocampal and cerebellar preparations after clarification of China ink-injected specimens by the Spalteholz method. This method may be suitable for global, three-dimensional, quantitative analyses of vessels, including stereological estimations of total volume and length and of surface area of vessels, which constitute indirect approaches to investigate angiogenesis.
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Affiliation(s)
- R C Gutierre
- Department of Neurology and Neurosurgery, Escola Paulista de Medicina, Universidade Federal de São Paulo (UNIFESP), São Paulo, Brazil.,Department of Physiology, Escola Paulista de Medicina, Universidade Federal de São Paulo (UNIFESP), São Paulo, Braz
| | - D Vannucci Campos
- Department of Neurology and Neurosurgery, Escola Paulista de Medicina, Universidade Federal de São Paulo (UNIFESP), São Paulo, Brazil.,Department of Physiology, Escola Paulista de Medicina, Universidade Federal de São Paulo (UNIFESP), São Paulo, Braz
| | - R A Mortara
- Department of Microbiology, Immunology and Parasitology, Escola Paulista de Medicina, Universidade Federal de São Paulo (UNIFESP), São Paulo, Brazil
| | - A A Coppi
- Faculty of Health and Medical Sciences, School of Veterinary Medicine, University of Surrey, Guildford, Surrey, UK
| | - R M Arida
- Department of Neurology and Neurosurgery, Escola Paulista de Medicina, Universidade Federal de São Paulo (UNIFESP), São Paulo, Brazil
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17
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Moutsatsos IK, Hossain I, Agarinis C, Harbinski F, Abraham Y, Dobler L, Zhang X, Wilson CJ, Jenkins JL, Holway N, Tallarico J, Parker CN. Jenkins-CI, an Open-Source Continuous Integration System, as a Scientific Data and Image-Processing Platform. SLAS DISCOVERY 2016; 22:238-249. [PMID: 27899692 PMCID: PMC5322829 DOI: 10.1177/1087057116679993] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
High-throughput screening generates large volumes of heterogeneous data that require a diverse set of computational tools for management, processing, and analysis. Building integrated, scalable, and robust computational workflows for such applications is challenging but highly valuable. Scientific data integration and pipelining facilitate standardized data processing, collaboration, and reuse of best practices. We describe how Jenkins-CI, an “off-the-shelf,” open-source, continuous integration system, is used to build pipelines for processing images and associated data from high-content screening (HCS). Jenkins-CI provides numerous plugins for standard compute tasks, and its design allows the quick integration of external scientific applications. Using Jenkins-CI, we integrated CellProfiler, an open-source image-processing platform, with various HCS utilities and a high-performance Linux cluster. The platform is web-accessible, facilitates access and sharing of high-performance compute resources, and automates previously cumbersome data and image-processing tasks. Imaging pipelines developed using the desktop CellProfiler client can be managed and shared through a centralized Jenkins-CI repository. Pipelines and managed data are annotated to facilitate collaboration and reuse. Limitations with Jenkins-CI (primarily around the user interface) were addressed through the selection of helper plugins from the Jenkins-CI community.
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Affiliation(s)
| | - Imtiaz Hossain
- 2 Centre for Proteomic Chemistry, NIBR, Postfach, Basel, Switzerland
| | - Claudia Agarinis
- 3 Developmental and Molecular Pathways, NIBR, Postfach, Basel, Switzerland
| | | | - Yann Abraham
- 5 The Janssen Pharmaceutical Companies of Johnson & Johnson, Beerse, Vlaanderen, Belgium
| | - Luc Dobler
- 6 République et Canton du Jura, Switzerland
| | - Xian Zhang
- 2 Centre for Proteomic Chemistry, NIBR, Postfach, Basel, Switzerland
| | | | - Jeremy L Jenkins
- 1 Developmental and Molecular Pathways, NIBR, Cambridge, MA, USA
| | - Nicholas Holway
- 7 Scientific Computing, NIBR Informatics, Novartis, Postfach, Basel, Switzerland
| | - John Tallarico
- 1 Developmental and Molecular Pathways, NIBR, Cambridge, MA, USA
| | - Christian N Parker
- 3 Developmental and Molecular Pathways, NIBR, Postfach, Basel, Switzerland
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18
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Landegger LD, Honeder C, Zhu C, Schöpper H, Engleder E, Gabor F, Gstoettner W, Arnoldner C. Noise trauma and systemic application of the selective glucocorticoid receptor modulator compound A. J Negat Results Biomed 2016; 15:10. [PMID: 27164957 PMCID: PMC4863352 DOI: 10.1186/s12952-016-0053-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Accepted: 04/13/2016] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Selective glucocorticoid receptor modulators (SEGRMs) comprise a novel class of drugs promising both reduced side effects and similar pharmacological potency relative to glucocorticoids, which presently serve as the only clinical treatment for many otologic disorders. In the first otologic SEGRM experiment in an animal model of noise trauma, we compare the effects of Compound A (a SEGRM) and dexamethasone (potent glucocorticoid). METHODS Forty adult guinea pigs received experimental treatment once daily for ten days. The animals were divided into four cohorts based on the treatment received: Compound A (1 mg/kg or 3 mg/kg), dexamethasone (1 mg/kg) as gold standard, or water as negative control. After five applications, animals were exposed to broadband noise (8-16 kHz) at 115 dB for three hours. Hearing thresholds were determined by recording auditory brainstem responses to clicks and noise bursts (1-32 kHz) and were assessed a week prior to and immediately after exposure, as well as on days 1, 3, 7, 14, 21, and 28. Cochleae were prepared as whole-mounts or embedded and sectioned for histological analysis. RESULTS Relative to the control treatments, Compound A failed to preserve auditory thresholds post-noise exposure with statistical significance. Histological analyses confirm the physiological result. CONCLUSION The present findings suggest that Compound A does not have substantial otoprotective capacities in a noise trauma model.
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Affiliation(s)
- Lukas D Landegger
- Department of Otorhinolaryngology, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria
| | - Clemens Honeder
- Department of Otorhinolaryngology, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria.
| | - Chengjing Zhu
- Department of Otorhinolaryngology, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria
| | - Hanna Schöpper
- Department of Pathobiology, Institute of Anatomy, Histology and Embryology, University of Veterinary Medicine, Veterinaerplatz 1, 1210, Vienna, Austria
| | - Elisabeth Engleder
- Department of Pharmaceutical Technology and Biopharmaceutics, University of Vienna, Althanstrasse 14, 1090, Vienna, Austria
| | - Franz Gabor
- Department of Pharmaceutical Technology and Biopharmaceutics, University of Vienna, Althanstrasse 14, 1090, Vienna, Austria
| | - Wolfgang Gstoettner
- Department of Otorhinolaryngology, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria
| | - Christoph Arnoldner
- Department of Otorhinolaryngology, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria
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Wrzeszcz A, Steffens M, Balster S, Warnecke A, Dittrich B, Lenarz T, Reuter G. Hydrogel coated and dexamethasone releasing cochlear implants: quantification of fibrosis in guinea pigs and evaluation of insertion forces in a human cochlea model. J Biomed Mater Res B Appl Biomater 2014; 103:169-78. [PMID: 24811046 DOI: 10.1002/jbm.b.33187] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Accepted: 04/05/2014] [Indexed: 12/18/2022]
Abstract
The insertion of cochlear implants (CIs) often causes fibrous tissue growth around the electrode, which leads to attenuation of function of CIs. Inhibition of fibrosis in vivo using dexamethasone (Dex) released from the implant base material (polydimethylsiloxane [PDMS]) coated with a protein repelling hydrogel (star-shaped polyethylene glycol prepolymer, sPEG) was, therefore, the aim of the study. PDMS filaments with Dex or sPEG were implanted into guinea pigs. The hearing status after implantation did not differ significantly in the treated groups. Using confocal laser scanning microscopy in transparent whole mount preparations, Dex, Dex/sPEG, as well as sPEG showed a tendency toward reduced formation of connective tissue around the implant. To apply such coatings for glass fibers for optical stimulation of the inner ear, insertion forces were measured into a human scala tympani model using fibers with sPEG coating. The results show that the hydrogel did not reduce insertion forces compared to the uncoated samples. However, PDMS-embedded fibers provide comparable insertion forces and depth to those measured with conventional CI electrodes, demonstrating the suitability of laser fibers for a minimal traumatic cochlear implantation.
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Affiliation(s)
- Antonina Wrzeszcz
- Department of Otolaryngology, Hannover Medical School, Hannover, 30625, Germany
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