Dr. Landegger is a clinician-scientist (otolaryngologist-head and neck surgeon) and Instructor at Stanford University School of Medicine. After gaining clinical as well as research experience in various countries (US, UK, France, Spain, Germany, Singapore, Australia), he specialized in otology with translational hearing research in Vienna, Austria and for five years in Boston (Mass Eye and Ear, Harvard Medical School), leading to a PhD in Neuroscience. Apart from clinical projects, current basic research foci are funded by a grant obtained from the American Society of Gene & Cell Therapy and include inner ear gene therapy, vestibular schwannoma, noise-induced hearing loss, and others.

Academic Appointments

  • Instructor, Otolaryngology (Head and Neck Surgery)

Honors & Awards

  • Research Prize Tinnitus and Hearing 2022, Foundation Tinnitus and Hearing Charité (Berlin, Germany) (December 2022)
  • Science Award of the Society, Austrian Society of Oto-Rhino-Laryngology – Head and Neck Surgery (September 2020)
  • Wilhelm Auerswald Prize, College of Physicians in Vienna (June 2018)
  • Poster Session Award, Austrian Marshall Plan Foundation (October 2017)
  • Hansaton Science Award, Austrian Society of Oto-Rhino-Laryngology – Head and Neck Surgery (September 2016)
  • Meritorious Abstract Travel Award, American Society of Gene and Cell Therapy (May 2016)
  • Heinz Kurz Poster Prize (3x), Austrian Society of Oto-Rhino-Laryngology – Head and Neck Surgery (September 2015, September 2016, October 2018)
  • Travel grant, Association for Research in Otolaryngology (February 2015)
  • Travel grant and Junior Poster Prize, European Academy of Allergy and Clinical Immunology (June 2012)

Boards, Advisory Committees, Professional Organizations

  • Editorial Board Member, Molecular Therapy - Methods and Clinical Development (2023 - Present)
  • Member Resident, American Academy of Otolaryngology-Head and Neck Surgery (2020 - Present)
  • International Member, German Society of Oto-Rhino-Laryngology, Head and Neck Surgery (2018 - Present)
  • Trainee Member, American Neurotology Society (2016 - Present)
  • Member, International Otopathology Society (Schuknecht Society) (2016 - Present)
  • Associate Member, American Society of Gene and Cell Therapy (2016 - Present)
  • Member, Austrian Society of Oto-Rhino-Laryngology – Head and Neck Surgery (2015 - Present)
  • ARO International Committee Chair 2021/2022, ARO Membership Committee Chair 2022-2024, Association for Research in Otolaryngology (2013 - Present)

Professional Education

  • Residency, Otolaryngology – Head and Neck Surgery, Vienna General Hospital, Medical University of Vienna, Austria (2023)
  • PhD, (Clinical) Neuroscience, Medical University of Vienna, Austria (2018)
  • Research Fellowship (Postdoc), Mass Eye and Ear, Harvard Medical School (2018)
  • MD, Medical University of Innsbruck, Austria (2011)

All Publications

  • Early Results With the New Active Bone-Conduction Hearing Implant: A Systematic Review and Meta-Analysis. Otolaryngology--head and neck surgery : official journal of American Academy of Otolaryngology-Head and Neck Surgery Lein, A., Baumgartner, W. D., Riss, D., Gstöttner, W., Landegger, L. D., Liu, D. T., Thurner, T., Vyskocil, E., Brkic, F. F. 2024


    The bone conduction implant (BCI) 602 is a new transcutaneous BCI with smaller dimensions. However, limited patient numbers restrict the statistical power and generalizability of the current studies. The present systematic review and meta-analysis summarize early audiological and medical outcomes of adult and pediatric patients implanted with the BCI 602 due to mixed or conductive hearing loss.Following the Preferred Reporting items for Systematic Reviews and Meta-analyses guidelines, 108 studies were reviewed, and 6 (5.6%) were included in the meta-analysis.The data on study and patient characteristics, surgical outcomes, and audiological test results were extracted from each article. Meta-analysis employed the fixed-effect and random-effects models to analyze the mean differences (MDs) between pre- and postoperative performances.In total, 116 patients were evaluated, including 64 (55%) adult and 52 (45%) pediatric patients. No intraoperative adverse events were reported, while postoperative complications were reported in 2 (3.1%) adult and 2 (3.8%) pediatric patients. Studies consistently showed significant improvements in audiological outcomes, quality of life, and sound localization in the aided condition. In the meta-analysis, we observed a significant difference in the unaided compared to the aided condition in sound field thresholds (n = 112; MD, -27.05 dB; P < 0.01), signal-to-noise ratio (n = 96; MD, -6.35 dB; P < 0.01), and word recognition scores (n = 96; MD, 68.89%; P < 0.01).The implantation of the BCI 602 was associated with minimal surgical complications and excellent audiological outcomes for both the pediatric and the adult cohort. Therefore, our analysis indicates a high level of safety and reliability. Further research should focus on direct comparisons with other BCIs and long-term functional outcomes.

    View details for DOI 10.1002/ohn.728

    View details for PubMedID 38529662

  • First use of adeno-associated viruses in the human inner ear. Molecular therapy. Methods & clinical development Landegger, L. D. 2024; 32 (1): 101197

    View details for DOI 10.1016/j.omtm.2024.101197

    View details for PubMedID 38371610

    View details for PubMedCentralID PMC10869910

  • Identification of immune-related candidate biomarkers in plasma of patients with sporadic vestibular schwannoma. Science advances Vasilijic, S., Atai, N. A., Hyakusoku, H., Worthington, S., Ren, Y., Sagers, J. E., Sahin, M. I., Brown, A., Reddy, R., Malhotra, C., Fujita, T., Landegger, L. D., Lewis, R., Welling, D. B., Stankovic, K. M. 2023; 9 (45): eadf7295


    Vestibular schwannoma (VS) is an intracranial tumor arising from neoplastic Schwann cells and typically presenting with hearing loss. The traditional belief that hearing deficit is caused by physical expansion of the VS, compressing the auditory nerve, does not explain the common clinical finding that patients with small tumors can have profound hearing loss, suggesting that tumor-secreted factors could influence hearing ability in VS patients. We conducted profiling of patients' plasma for 66 immune-related factors in patients with sporadic VS (N > 170) and identified and validated candidate biomarkers associated with tumor size (S100B) and hearing (MCP-3). We further identified a nine-biomarker panel (TNR-R2, MIF, CD30, MCP-3, IL-2R, BLC, TWEAK, eotaxin, and S100B) with outstanding discriminatory ability for VS. These findings revealed possible therapeutic targets for VS, providing a unique diagnostic tool that may predict hearing change and tumor growth in VS patients, and may inform the timing of tumor resection to preserve hearing.

    View details for DOI 10.1126/sciadv.adf7295

    View details for PubMedID 37948527

    View details for PubMedCentralID PMC10637750

  • Large-scale annotated dataset for cochlear hair cell detection and classification. bioRxiv : the preprint server for biology Buswinka, C. J., Rosenberg, D. B., Simikyan, R. G., Osgood, R. T., Fernandez, K., Nitta, H., Hayashi, Y., Liberman, L. W., Nguyen, E., Yildiz, E., Kim, J., Jarysta, A., Renauld, J., Wesson, E., Thapa, P., Bordiga, P., McMurtry, N., Llamas, J., Kitcher, S. R., López-Porras, A. I., Cui, R., Behnammanesh, G., Bird, J. E., Ballesteros, A., Vélez-Ortega, A. C., Edge, A. S., Deans, M. R., Gnedeva, K., Shrestha, B. R., Manor, U., Zhao, B., Ricci, A. J., Tarchini, B., Basch, M., Stepanyan, R. S., Landegger, L. D., Rutherford, M., Liberman, M. C., Walters, B. J., Kros, C. J., Richardson, G. P., Cunningham, L. L., Indzhykulian, A. A. 2023


    Our sense of hearing is mediated by cochlear hair cells, localized within the sensory epithelium called the organ of Corti. There are two types of hair cells in the cochlea, which are organized in one row of inner hair cells and three rows of outer hair cells. Each cochlea contains a few thousands of hair cells, and their survival is essential for our perception of sound because they are terminally differentiated and do not regenerate after insult. It is often desirable in hearing research to quantify the number of hair cells within cochlear samples, in both pathological conditions, and in response to treatment. However, the sheer number of cells along the cochlea makes manual quantification impractical. Machine learning can be used to overcome this challenge by automating the quantification process but requires a vast and diverse dataset for effective training. In this study, we present a large collection of annotated cochlear hair-cell datasets, labeled with commonly used hair-cell markers and imaged using various fluorescence microscopy techniques. The collection includes samples from mouse, human, pig and guinea pig cochlear tissue, from normal conditions and following in-vivo and in-vitro ototoxic drug application. The dataset includes over 90'000 hair cells, all of which have been manually identified and annotated as one of two cell types: inner hair cells and outer hair cells. This dataset is the result of a collaborative effort from multiple laboratories and has been carefully curated to represent a variety of imaging techniques. With suggested usage parameters and a well-described annotation procedure, this collection can facilitate the development of generalizable cochlear hair cell detection models or serve as a starting point for fine-tuning models for other analysis tasks. By providing this dataset, we aim to supply other groups within the hearing research community with the opportunity to develop their own tools with which to analyze cochlear imaging data more fully, accurately, and with greater ease.

    View details for DOI 10.1101/2023.08.30.553559

    View details for PubMedID 37693382

    View details for PubMedCentralID PMC10491224

  • Dupilumab reduces symptom burden in allergic rhinitis and suppresses allergen-specific IgE production. Allergy Campion, N. J., Doralt, A., Lupinek, C., Berger, M., Poglitsch, K., Brugger, J., Quint, T., Gangl, K., Sinz, C., Bartosik, T., Liu, D. T., Landegger, L. D., Tu, A., Stanek, V., Berger, U., Bangert, C., Schneider, S., Eckl-Dorna, J. 2023; 78 (6): 1687-1691

    View details for DOI 10.1111/all.15653

    View details for PubMedID 36691369

  • Patient Acceptance of Novel Therapeutic Options for Sensorineural Hearing Loss-A Pilot Study. Otology & neurotology : official publication of the American Otological Society, American Neurotology Society [and] European Academy of Otology and Neurotology Lembacher, M. J., Arnoldner, C., Landegger, L. D. 2023; 44 (4): e204-e210


    Numerous preclinical experiments over the past years have shown the potential of novel therapeutic approaches for sensorineural hearing loss (SNHL) that are now awaiting clinical translation. In this pilot study, we aimed to evaluate the patient acceptance of these future innovative therapies in individuals with SNHL.Cross-sectional exploratory pilot study.Tertiary care academic hospital.In total, 72 individuals (43 female and 29 male, 59 affected subjects and 13 parents) with different types of SNHL were surveyed between May 2020 and November 2020.The interest/willingness to consider new therapeutic options (viral vectors, stem cells, CRISPR/Cas) for themselves or their children was assessed with the help of a questionnaire, and the answers were matched with a quality-of-life score and sociodemographic as well as clinical characteristics.Acceptance of new therapeutic strategies for SNHL in a representative population.Even with the currently associated treatment uncertainties, 48 patients (66.7%) suffering from SNHL stated that new therapies could be a potential future option for them. Half of these (24 individuals; 33.3%) expressed high acceptance toward the novel strategies. Subjects with a positive attitude toward new therapies in general and viral vectors specifically were significantly older.With two-thirds of patients affected by SNHL expressing acceptance toward novel therapies, this pilot study highlights the importance of investigating such attitudes and motivates further translational research to offer additional treatment strategies to this patient population.

    View details for DOI 10.1097/MAO.0000000000003828

    View details for PubMedID 36791369

  • Investigation of inner ear drug delivery with a cochlear catheter in piglets as a representative model for human cochlear pharmacokinetics. Frontiers in pharmacology Yildiz, E., Gadenstaetter, A. J., Gerlitz, M., Landegger, L. D., Liepins, R., Nieratschker, M., Glueckert, R., Staecker, H., Honeder, C., Arnoldner, C. 2023; 14: 1062379


    Hearing impairment is the most common sensory disorder in humans, and yet hardly any medications are licensed for the treatment of inner ear pathologies. Intricate pharmacokinetic examinations to better understand drug distribution within this complex organ could facilitate the development of novel therapeutics. For such translational research projects, animal models are indispensable, but differences in inner ear dimensions and other anatomical features complicate the transfer of experimental results to the clinic. The gap between rodents and humans may be bridged using larger animal models such as non-human primates. However, their use is challenging and impeded by administrative, regulatory, and financial hurdles. Other large animal models with more human-like inner ear dimensions are scarce. In this study, we analyzed the inner ears of piglets as a potential representative model for the human inner ear and established a surgical approach for intracochlear drug application and subsequent apical sampling. Further, controlled intracochlear delivery of fluorescein isothiocyanate-dextran (FITC-d) was carried out after the insertion of a novel, clinically applicable CE-marked cochlear catheter through the round window membrane. Two, six, and 24 hours after a single injection with this device, the intracochlear FITC-d distribution was determined in sequential perilymph samples. The fluorometrically assessed concentrations two hours after injection were compared to the FITC-d content in control groups, which either had been injected with a simple needle puncture through the round window membrane or the cochlear catheter in combination with a stapes vent hole. Our findings demonstrate not only significantly increased apical FITC-d concentrations when using the cochlear catheter but also higher total concentrations in all perilymph samples. Additionally, the concentration decreased after six and 24 hours and showed a more homogenous distribution compared to shorter observation times.

    View details for DOI 10.3389/fphar.2023.1062379

    View details for PubMedID 36969846

    View details for PubMedCentralID PMC10034346

  • Dupilumab increases aspirin tolerance in NSAID-exacerbated respiratory disease. The European respiratory journal Schneider, S., Poglitsch, K., Morgenstern, C., Quint, T., Gangl, K., Sinz, C., Bartosik, T., Campion, N. J., Liu, D. T., Landegger, L. D., Tu, A., Stanek, V., Rocha-Hasler, M., Bangert, C., Eckl-Dorna, J. 2023; 61 (3)


    Nonsteroidal anti-inflammatory drug (NSAID)-exacerbated respiratory disease (N-ERD) comprises the triad of chronic rhinosinusitis with nasal polyps, asthma and intolerance to NSAIDs. Dupilumab treatment, targeting the interleukin-4 (IL-4) receptor α, significantly reduces polyp burden as well as asthma symptoms. Here we aimed to investigate the effect of dupilumab on aspirin intolerance, burden of disease and nasal cytokine profiles in patients with N-ERD.In this open-label trial, adult patients with confirmed N-ERD were treated with dupilumab for 6 months. Clinical parameters (e.g. total polyp scores, quality of life questionnaires, smell test, spirometry), oral aspirin provocation testing and blood, nasal and urine sampling were monitored at regular intervals for up to 6 months after starting dupilumab therapy.Of the 31 patients included in the study, 30 completed both aspirin provocation tests. After 6 months of treatment with dupilumab, 23% of patients (n=7 of 30) developed complete aspirin tolerance and an additional 33% of patients (n=10 of 30) tolerated higher doses. Polyp burden was significantly reduced (total polyp score: -2.68±1.84, p<0.001), while pulmonary symptoms (asthma control test: +2.34±3.67, p<0.001) and olfactory performance improved (University of Pennsylvania Smell Identification Test: +11.16±9.54, p<0.001) in all patients after therapy. Patients with increased aspirin tolerance showed a significant decrease in urinary leukotriene E4 levels and their improvement in clinical parameters was associated with a reduction of eotaxin-1, C-C motif chemokine ligand 17, IL-5, IL-17A and IL-6.In this study, 57% of N-ERD patients tolerated higher doses of aspirin under dupilumab therapy.

    View details for DOI 10.1183/13993003.01335-2022

    View details for PubMedID 36549708

    View details for PubMedCentralID PMC10017890

  • Identification of Immune-Related Candidate Biomarkers in Plasma of Patients with Sporadic Vestibular Schwannoma: Candidate Plasma Biomarkers in Vestibular Schwannoma. bioRxiv : the preprint server for biology Vasilijic, S., Atai, N. A., Hyakusoku, H., Worthington, S., Ren, Y., Sagers, J. E., Sahin, M. I., Fujita, T., Landegger, L. D., Lewis, R., Welling, D. B., Stankovic, K. M. 2023


    Vestibular schwannoma (VS) is intracranial tumor arising from neoplastic Schwann cells, causing hearing loss in about 95% of patients. The traditional belief that hearing deficit is caused by physical expansion of the VS, compressing the auditory nerve, does not explain the common clinical finding that patients with small tumors can have profound hearing loss, suggesting that tumor-secreted factors could influence hearing ability in VS patients. Here, we conducted profiling of patients' plasma for 67 immune-related factors on a large cohort of VS patients (N>120) and identified candidate biomarkers associated with tumor growth (IL-16 and S100B) and hearing (MDC). We identified the 7-biomarker panel composed of MCP-3, BLC, S100B, FGF-2, MMP-14, eotaxin, and TWEAK that showed outstanding discriminatory ability for VS. These findings revealed possible therapeutic targets for VS-induced hearing loss and provided a unique diagnostic tool that may predict hearing change and tumor growth in VS patients and may help inform the ideal timing of tumor resection to preserve hearing.

    View details for DOI 10.1101/2023.01.24.525436

    View details for PubMedID 36747696

    View details for PubMedCentralID PMC9900840

  • miR-431 secreted by human vestibular schwannomas increases the mammalian inner ear's vulnerability to noise trauma. Frontiers in neurology Fujita, T., Seist, R., Kao, S., Soares, V., Panano, L., Khetani, R. S., Landegger, L. D., Batts, S., Stankovic, K. M. 2023; 14: 1268359


    Introduction: Vestibular schwannoma (VS) is an intracranial tumor that arises on the vestibular branch of cranial nerve VIII and typically presents with sensorineural hearing loss (SNHL). The mechanisms of this SNHL are postulated to involve alterations in the inner ear's microenvironment mediated by the genetic cargo of VS-secreted extracellular vesicles (EVs). We aimed to identify the EV cargo associated with poor hearing and determine whether its delivery caused hearing loss and cochlear damage in a mouse model in vivo.Methods: VS tissue was collected from routinely resected tumors of patients with good (VS-GH) or poor (VS-PH) pre-surgical hearing measured via pure-tone average and word recognition scores. Next-generation sequencing was performed on RNA isolated from cultured primary human VS cells and EVs from VS-conditioned media, stratified by patients' hearing ability. microRNA expression levels were compared between VS-PH and VS-GH samples to identify differentially expressed candidates for packaging into a synthetic adeno-associated viral vector (Anc80L65). Viral vectors containing candidate microRNA were infused to the semicircular canals of mice to evaluate the effects on hearing, including after noise exposure.Results: Differentially expressed microRNAs included hsa-miR-431-5p (enriched in VS-PH) and hsa-miR-192-5p (enriched in VS-GH). Newborn mice receiving intracochlear injection of viral vectors over-expressing hsa-miR-431-GFP, hsa-miR-192-GFP, or GFP only (control) had similar hearing 6weeks post-injection. However, after acoustic trauma, the miR-431 group displayed significantly worse hearing, and greater loss of synaptic ribbons per inner hair cell in the acoustically traumatized cochlear region than the control group.Conclusion: Our results suggest that miR-431 contributes to VS-associated hearing loss following cochlear stress. Further investigation is needed to determine whether miR-431 is a potential therapeutic target for SNHL.

    View details for DOI 10.3389/fneur.2023.1268359

    View details for PubMedID 37885485

  • Single-incision cochlear implantation and hearing evaluation in piglets and minipigs. Hearing research Yildiz, E., Gerlitz, M., Gadenstaetter, A. J., Landegger, L. D., Nieratschker, M., Schum, D., Schmied, M., Haase, A., Kanz, F., Kramer, A. M., Glueckert, R., Staecker, H., Honeder, C., Arnoldner, C. 2022; 426: 108644


    Various animal models have been established and applied in hearing research. In the exploration of novel cochlear implant developments, mainly rodents have been used. Despite their important contribution to the understanding of auditory function, translation of experimental observations from rodents to humans is limited due to the size differences and genetic variability. Large animal models with better representation of the human cochlea are sparse. For this reason, we evaluated domestic piglets and Aachen minipigs for the suitability as a cochlear implantation animal model with commercially available cochlear implants.Four domestic piglets (two male and two female) and six Aachen minipigs were implanted with either MED-EL Flex24 or Flex20 cochlear implants respectively, after a step-by-step surgical approach was trained with pig cadavers. Electrophysiological measurements were performed before, during and after implantation for as long as 56 days after surgery. Auditory brainstem responses, electrocochleography as well as electrically and acoustically evoked compound action potentials were recorded. Selected cochleae were further analyzed histologically or with micro-CT imaging.A surgical approach was established using a retroauricular single incision. Baseline auditory thresholds were 27 ± 3 dB sound pressure level (SPL; auditory brainstem click responses, mean ± standard error of the mean) and ranged between 30 and 80 dB SPL in frequency-specific responses (0.5 - 32 kHz). Follow-up measurements revealed deafness within the first two weeks after surgery, but some animals partially recovered to a hearing threshold of 80 dB SPL in certain frequencies as well as in click responses. Electrically evoked compound action potential thresholds increased within the first week after surgery, which led to lower stimulation responses or increase of necessary charge input. Immune reactions and consecutive scalar fibrosis following implantation were confirmed with histological analysis of implanted cochleae and may result in increased impedances. A three-dimensional minipig micro-CT segmentation revealed cochlear volumetric data similar to human inner ear dimensions.This study underlines the feasibility of cochlear implantation with clinically used cochlear implants in a large animal model with representative inner ear dimensions comparable to humans. To bridge the gap between small animal models and humans in translational research and to account for the structural and size differences, we recommend the minipig as a valuable animal model for hearing research. First insights into the induced trauma in minipigs after cochlear implant surgery and a partial hearing recovery present important data of the cochlear health changes in large animal cochleae.

    View details for DOI 10.1016/j.heares.2022.108644

    View details for PubMedID 36343533

  • Intranasal application of adeno-associated viruses: a systematic review. Translational research : the journal of laboratory and clinical medicine Gadenstaetter, A. J., Schmutzler, L., Grimm, D., Landegger, L. D. 2022; 248: 87-110


    Adeno-associated viruses (AAVs) represent some of the most commonly employed vectors for targeted gene delivery and their extensive study has resulted in the approval of multiple gene therapies to treat human diseases. The intranasal route of vector application in gene therapy offers several advantages over traditional ways of administration. In addition to targeting local tissue like the olfactory epithelium, it provides minimally invasive access to various organ systems, including the central nervous system and the respiratory tract. Through a systematic literature review, a total of 53 articles that investigated the intranasal application of AAVs were identified, included, and summarized in this manuscript. Within these studies, AAV-based gene therapy was mainly investigated for its application in various infectious, pulmonary, or neurologic and/or psychiatric diseases. This review gives a comprehensive overview of the current technological state of the art regarding the intranasal application of AAVs for gene transfer and discusses remaining hurdles, which still have to be resolved before this approach can effectively be implemented in the routine clinical setting.

    View details for DOI 10.1016/j.trsl.2022.05.002

    View details for PubMedID 35597541

  • Editorial: Otologic Trauma, Pathology, and Therapy. Frontiers in cellular neuroscience Landegger, L. D., Fujita, T., Jan, T. A., Varela-Nieto, I. 2022; 16: 900074

    View details for DOI 10.3389/fncel.2022.900074

    View details for PubMedID 35496907

    View details for PubMedCentralID PMC9043112

  • Tuberculous Abscesses in the Head and Neck Region. Diagnostics (Basel, Switzerland) Landegger, L. D. 2022; 12 (3)


    Tuberculosis represents a global health challenge and is one of the leading infectious killers, with over a million people succumbing to it every year. While the disease is primarily prevalent in developing countries, where 95% of cases and deaths occur, doctors around the globe need to be able to recognize its diverse clinical manifestations in order to initiate appropriate treatment early. The granulomatous infection caused by Mycobacterium tuberculosis typically affects the lungs, but isolated abscesses in the head and neck region can be a less common presentation of the disease, potentially resulting in dysphagia, odynophagia, voice changes, neck swelling, bone erosion, and even life-threatening respiratory distress requiring tracheostomy. Here, characteristic imaging findings and potential surgical options are discussed.

    View details for DOI 10.3390/diagnostics12030686

    View details for PubMedID 35328238

    View details for PubMedCentralID PMC8947371

  • Temporal fluctuations of post-tonsillectomy haemorrhage. European archives of oto-rhino-laryngology : official journal of the European Federation of Oto-Rhino-Laryngological Societies (EUFOS) : affiliated with the German Society for Oto-Rhino-Laryngology - Head and Neck Surgery Grasl, S., Mekhail, P., Janik, S., Grasl, C. M., Vyskocil, E., Erovic, B. M., Arnoldner, C., Landegger, L. D. 2022; 279 (3): 1601-1607


    Although haemorrhage is a common and in some cases life-threatening complication after tonsillectomy, surprisingly little is known about the temporal fluctuations of the onset of bleeding. The purpose of this study was to assess circadian and seasonal rhythms of post-tonsillectomy haemorrhage (PTH) and potential ramifications to educate patients and health care staff.This retrospective study carried out at a tertiary referral hospital included paediatric and adult patients requiring emergency surgery due to severe PTH between 1993 and 2019. Medical records were reviewed and patient demographics, details regarding the initial procedure, postoperative day of haemorrhage, and start time of emergency surgery were extracted. Descriptive statistics, Kruskal-Wallis test, Mann-Whitney U test, and Chi-square goodness of fit tests were used to detect potential differences.A total of 300 patients with severe PTH and subsequent emergency surgery were identified. The median postoperative duration until PTH was 6 (range: < 1-19) days. 64.7% (n = 194) of all emergency surgeries had to be performed during evening and night hours (6 pm-6 am) (p < 0.0001). Compared to diurnal incidents, the risk of a nocturnal PTH event increased, the longer ago the initial surgery was (p < 0.0001). No seasonal variations were identified. Age, sex, and details of the initial procedure had no significant influence on the start time according to the surgical protocol.The discovered temporal fluctuations of PTH are of relevance for patient awareness and preoperative education. Due to possible life-threatening complications, management of severe PTH requires specific resources and trained medical staff on call.

    View details for DOI 10.1007/s00405-021-07080-1

    View details for PubMedID 34557959

    View details for PubMedCentralID PMC8897317

  • Choice of vector and surgical approach enables efficient cochlear gene transfer in nonhuman primate. Nature communications Andres-Mateos, E., Landegger, L. D., Unzu, C., Phillips, J., Lin, B. M., Dewyer, N. A., Sanmiguel, J., Nicolaou, F., Valero, M. D., Bourdeu, K. I., Sewell, W. F., Beiler, R. J., McKenna, M. J., Stankovic, K. M., Vandenberghe, L. H. 2022; 13 (1): 1359


    Inner ear gene therapy using adeno-associated viral vectors (AAV) promises to alleviate hearing and balance disorders. We previously established the benefits of Anc80L65 in targeting inner and outer hair cells in newborn mice. To accelerate translation to humans, we now report the feasibility and efficiency of the surgical approach and vector delivery in a nonhuman primate model. Five rhesus macaques were injected with AAV1 or Anc80L65 expressing eGFP using a transmastoid posterior tympanotomy approach to access the round window membrane after making a small fenestra in the oval window. The procedure was well tolerated. All but one animal showed cochlear eGFP expression 7-14 days following injection. Anc80L65 in 2 animals transduced up to 90% of apical inner hair cells; AAV1 was markedly less efficient at equal dose. Transduction for both vectors declined from apex to base. These data motivate future translational studies to evaluate gene therapy for human hearing disorders.

    View details for DOI 10.1038/s41467-022-28969-3

    View details for PubMedID 35292639

  • Breaking the sound barrier: Towards next-generation AAV vectors for gene therapy of hearing disorders. Hearing research Fakhiri, J., Landegger, L. D., Grimm, D. 2022; 413: 108092


    Owing to the advances in transgenic animal technology and the advent of the next-generation sequencing era, over 120 genes causing hereditary hearing loss have been identified by now. In parallel, the field of human gene therapy continues to make exciting and rapid progress, culminating in the recent approval of several ex vivo and in vivo applications. Despite these encouraging developments and the growing interest in causative treatments for hearing disorders, gene therapeutic interventions in the inner ear remain in their infancy and await clinical translation. This review focuses on the adeno-associated virus (AAV), which nowadays represents one of the safest and most promising vectors in gene therapy. We first provide an overview of AAV biology and outline the principles of therapeutic gene transfer with recombinant AAV vectors, before pointing out major challenges and solutions for clinical translation including vector manufacturing and species translatability. Finally, we highlight seminal technologies for engineering and selection of next-generation "designer" AAV capsids, and illustrate their power and potential with recent examples of their application for inner ear gene transfer in animals.

    View details for DOI 10.1016/j.heares.2020.108092

    View details for PubMedID 33268240

  • Losartan prevents tumor-induced hearing loss and augments radiation efficacy in NF2 schwannoma rodent models. Science translational medicine Wu, L., Vasilijic, S., Sun, Y., Chen, J., Landegger, L. D., Zhang, Y., Zhou, W., Ren, J., Early, S., Yin, Z., Ho, W. W., Zhang, N., Gao, X., Lee, G. Y., Datta, M., Sagers, J. E., Brown, A., Muzikansky, A., Stemmer-Rachamimov, A., Zhang, L., Plotkin, S. R., Jain, R. K., Stankovic, K. M., Xu, L. 2021; 13 (602)


    Hearing loss is one of the most common symptoms of neurofibromatosis type 2 (NF2) caused by vestibular schwannomas (VSs). Fibrosis in the VS tumor microenvironment (TME) is associated with hearing loss in patients with NF2. We hypothesized that reducing the fibrosis using losartan, an FDA-approved antihypertensive drug that blocks fibrotic and inflammatory signaling, could improve hearing. Using NF2 mouse models, we found that losartan treatment normalized the TME by (i) reducing neuroinflammatory IL-6/STAT3 signaling and preventing hearing loss, (ii) normalizing tumor vasculature and alleviating neuro-edema, and (iii) increasing oxygen delivery and enhancing efficacy of radiation therapy. In preparation to translate these exciting findings into the clinic, we used patient samples and data and demonstrated that IL-6/STAT3 signaling inversely associated with hearing function, that elevated production of tumor-derived IL-6 was associated with reduced viability of cochlear sensory cells and neurons in ex vivo organotypic cochlear cultures, and that patients receiving angiotensin receptor blockers have no progression in VS-induced hearing loss compared with patients on other or no antihypertensives based on a retrospective analysis of patients with VS and hypertension. Our study provides the rationale and critical data for a prospective clinical trial of losartan in patients with VS.

    View details for DOI 10.1126/scitranslmed.abd4816

    View details for PubMedID 34261799

  • Cochlin Deficiency Protects Against Noise-Induced Hearing Loss FRONTIERS IN MOLECULAR NEUROSCIENCE Seist, R., Landegger, L. D., Robertson, N. G., Vasilijic, S., Morton, C. C., Stankovic, K. M. 2021; 14: 670013


    Cochlin is the most abundant protein in the inner ear. To study its function in response to noise trauma, we exposed adolescent wild-type (Coch +/+ ) and cochlin knock-out (Coch -/-) mice to noise (8-16 kHz, 103 dB SPL, 2 h) that causes a permanent threshold shift and hair cell loss. Two weeks after noise exposure, Coch-/- mice had substantially less elevation in noise-induced auditory thresholds and hair cell loss than Coch + / + mice, consistent with cochlin deficiency providing protection from noise trauma. Comparison of pre-noise exposure thresholds of auditory brain stem responses (ABRs) and distortion product otoacoustic emissions (DPOAEs) in Coch-/- mice and Coch + / + littermates revealed a small and significant elevation in thresholds of Coch-/- mice, overall consistent with a small conductive hearing loss in Coch-/- mice. We show quantitatively that the pro-inflammatory component of cochlin, LCCL, is upregulated after noise exposure in perilymph of wild-type mice compared to unexposed mice, as is the enzyme catalyzing LCCL release, aggrecanase1, encoded by Adamts4. We further show that upregulation of pro-inflammatory cytokines in perilymph and cochlear soft-tissue after noise exposure is lower in cochlin knock-out than wild-type mice. Taken together, our data demonstrate for the first time that cochlin deficiency results in conductive hearing loss that protects against physiologic and molecular effects of noise trauma.

    View details for DOI 10.3389/fnmol.2021.670013

    View details for Web of Science ID 000658161600001

    View details for PubMedID 34108864

    View details for PubMedCentralID PMC8180578

  • Postnatal expression and possible function of RANK and RANKL in the murine inner ear BONE Kao, S., Katsumi, S., Han, D., Bizaki-Vallaskangas, A. J., Vasilijic, S., Landegger, L. D., Kristiansen, A. G., McKenna, M. J., Stankovic, K. M. 2021; 145: 115837


    The bone encasing the inner ear, known as the otic capsule, is unique because it remodels little postnatally compared to other bones in the body. Previous studies established that osteoprotegerin (OPG) in the inner ear inhibits otic capsule remodeling. OPG acts as a decoy receptor of receptor activator of nuclear factor κB ligand (RANKL) to disrupt the interaction between RANKL and RANK, the primary regulators of bone metabolism. Here we studied the expression and function of RANK and RANKL in the murine cochlea. Using a combination of in situ hybridization, real-time quantitative RT-PCR, and western blot, we demonstrate that Rankl and Rank genes and their protein products are expressed in the intracochlear soft tissues and the otic capsule in a developmentally regulated manner. Using a culture of neonatal murine cochlear neurons, we show that the interaction between RANK and RANKL inhibits neurite outgrowth in these neurons, and is associated with upregulation of NOGO-A expression. Taken together, our results suggest that, in addition to regulating otic capsule bone remodeling, RANK and RANKL expressed by intracochlear soft tissues may also regulate spiral ganglion neuron function by affecting neurite outgrowth.

    View details for DOI 10.1016/j.bone.2020.115837

    View details for Web of Science ID 000623120700009

    View details for PubMedID 33385614

  • Overcoming Operator-Generated False-Negative Results in SARS-CoV-2 Testing. JAMA otolaryngology-- head & neck surgery Landegger, L. D. 2021; 147 (4): 403

    View details for DOI 10.1001/jamaoto.2020.5576

    View details for PubMedID 33599703

  • Simultaneous Vestibular Schwannoma Resection and Cochlear Implantation Using Electrically Evoked Auditory Brainstem Response Audiometry for Decision-making. Otology & neurotology : official publication of the American Otological Society, American Neurotology Society [and] European Academy of Otology and Neurotology Dahm, V., Auinger, A. B., Honeder, C., Riss, D., Landegger, L. D., Moser, G., Matula, C., Arnoldner, C. 2020; 41 (9): 1266-1273


    The aim of the study was to evaluate the predictive value regarding postoperative hearing benefit of electrically evoked auditory brainstem response audiometry in sporadic vestibular schwannoma patients undergoing simultaneous tumor resection and cochlear implantation.Patients were included in a prospective study conducted between October 2016 and January 2019.The study was conducted at a tertiary care center.Subjects with unilateral sporadic vestibular schwannoma were screened for study participation. Patients underwent translabyrinthine vestibular schwannoma resection and cochlear implantation simultaneously.Electrically evoked brainstem response audiometry was performed during surgery before and after tumor removal using an intracochlear test electrode to objectively evaluate nerve conduction.Electrically evoked brainstem response audiometry results were correlated with postoperative sound field audiometry, word recognition tests, and speech reception thresholds. Quality of life was assessed before and 12 months after translabyrinthine tumor removal and cochlear implantation.Five patients, three male and two female, were included in the study and followed for at least 1 year after implantation. Three of the five patients are daily cochlear implant users with open set speech recognition. Two individuals with negative intraoperative electrically evoked auditory brainstem response results showed no auditory perception with cochlear implant.Simultaneous translabyrinthine vestibular schwannoma resection and cochlear implantation with intraoperative electrically evoked auditory brainstem response measurements is a feasible and promising option for sporadic vestibular schwannoma patients. Preservation of electrically evoked auditory brainstem responses seems to predict good subsequent hearing outcomes.

    View details for DOI 10.1097/MAO.0000000000002747

    View details for PubMedID 32925856

  • MMP-14 (MT1-MMP) Is a Biomarker of Surgical Outcome and a Potential Mediator of Hearing Loss in Patients With Vestibular Schwannomas. Frontiers in cellular neuroscience Ren, Y., Hyakusoku, H., Sagers, J. E., Landegger, L. D., Welling, D. B., Stankovic, K. M. 2020; 14: 191


    Improved biomarkers are needed for vestibular schwannoma (VS), the most common tumor of the cerebellopontine angle, as existing clinical biomarkers have poor predictive value. Factors such as tumor size or growth rate do not shed light on the pathophysiology of associated sensorineural hearing loss (SNHL) and suffer from low specificity and sensitivity, whereas histological markers only sample a fraction of the tumor and are difficult to ascertain before tumor treatment or surgical intervention. Proteases play diverse and critical roles in tumorigenesis and could be leveraged as a new class of VS biomarkers. Using a combination of in silico, in vitro, and ex vivo approaches, we identified matrixmetalloprotease 14 (MMP-14; also known as MT1-MMP), from a panel of candidate proteases that were differentially expressed through the largest meta-analysis of human VS transcriptomes. The abundance and proteolytic activity of MMP-14 in the plasma and tumor secretions from VS patients correlated with clinical parameters and the degree of SNHL. Further, MMP-14 plasma levels correlated with surgical outcomes such as the extent of resection. Finally, the application of MMP-14 at physiologic concentrations to cochlear explant cultures led to damage to spiral ganglion neuronal fibers and synapses, thereby providing mechanistic insight into VS-associated SNHL. Taken together, MMP-14 represents a novel molecular biomarker that merits further validation in both diagnostic and prognostic applications for VS.

    View details for DOI 10.3389/fncel.2020.00191

    View details for PubMedID 32848608

    View details for PubMedCentralID PMC7424165

  • Regeneration of Cochlear Synapses by Systemic Administration of a Bisphosphonate FRONTIERS IN MOLECULAR NEUROSCIENCE Seist, R., Tong, M., Landegger, L. D., Vasilijic, S., Hyakusoku, H., Katsumi, S., McKenna, C. E., Edge, A. B., Stankovic, K. M. 2020; 13: 87


    Sensorineural hearing loss (SNHL) caused by noise exposure and attendant loss of glutamatergic synapses between cochlear spiral ganglion neurons (SGNs) and hair cells is the most common sensory deficit worldwide. We show here that systemic administration of a bisphosphonate to mice 24 h after synaptopathic noise exposure regenerated synapses between inner hair cells and SGNs and restored cochlear function. We further demonstrate that this effect is mediated by inhibition of the mevalonate pathway. These results are highly significant because they suggest that bisphosphonates could reverse cochlear synaptopathy for the treatment of SNHL.

    View details for DOI 10.3389/fnmol.2020.00087

    View details for Web of Science ID 000556565200001

    View details for PubMedID 32765216

    View details for PubMedCentralID PMC7381223

  • Associations between the Quality of Life and Nasal Polyp Size in Patients Suffering from Chronic Rhinosinusitis without Nasal Polyps, with Nasal Polyps or Aspirin-Exacerbated Respiratory Disease. Journal of clinical medicine Schneider, S., Campion, N. J., Villazala-Merino, S., Liu, D. T., Bartosik, T., Landegger, L. D., Ahmadi, N., Mueller, C. A., Vyskocil, E., Stanek, V., Quint, T., Bangert, C., Eckl-Dorna, J. 2020; 9 (4)


    Chronic rhinosinusitis (CRS) is a common disease that substantially impairs the quality of life (QoL). Here, we aimed to assess patients' QoL in different subtypes of CRS and correlated this with nasal polyp size to improve the clinical understanding of the burden of disease. In this retrospective single-center study, 107 patients with the following diagnoses were analyzed: CRS without nasal polyps (CRSsNP), CRS with nasal polyps (CRSwNP), or aspirin-exacerbated respiratory disease (AERD). Sino-Nasal Outcome Test-20 German Adapted Version (SNOT-20 GAV) scores and their correlation with endoscopic Total Polyp Scores (TPS) were evaluated. The mean SNOT-20 GAV scores were highest in patients with AERD (AERD = 43.4, CRSwNP = 36.3, CRSsNP = 30.9). A statistically significant correlation of total SNOT-20 GAV score with TPS was observed in CRSwNP patients (r = 0.3398, p = 0.0195), but not in AERD patients (r = 0.2341, p = 0.1407). When analyzing single SNOT-20 parameters, a strong correlation with TPS was observed for blockage/congestion of the nose, particularly in AERD patients (r = 0.65, p < 0.0001). The impact of nasal polyp size on the QoL differs amongst the subgroups of CRS. Nasal symptoms have the greatest impact on QoL in patients suffering from AERD. CRSwNP and AERD patients should be separately analyzed in clinical investigations and interpretations due to significant differences in QoL.

    View details for DOI 10.3390/jcm9040925

    View details for PubMedID 32231056

    View details for PubMedCentralID PMC7230739

  • Intracochlear Perfusion of Tumor Necrosis Factor-Alpha Induces Sensorineural Hearing Loss and Synaptic Degeneration in Guinea Pigs FRONTIERS IN NEUROLOGY Katsumi, S., Sahin, M., Lewis, R. M., Iyer, J. S., Landegger, L. D., Stankovic, K. M. 2020; 10: 1353


    Tumor necrosis factor-alpha (TNF-α) is a proinflammatory cytokine that plays a prominent role in the nervous system, mediating a range of physiologic and pathologic functions. In the auditory system, elevated levels of TNF-α have been implicated in several types of sensorineural hearing loss, including sensorineural hearing loss induced by vestibular schwannoma, a potentially fatal intracranial tumor that originates from the eighth cranial nerve; however, the mechanisms underlying the tumor's deleterious effects on hearing are not well-understood. Here, we investigated the effect of acute elevations of TNF-α in the inner ear on cochlear function and morphology by perfusing the cochlea with TNF-α in vivo in guinea pigs. TNF-α perfusion did not significantly change thresholds for compound action potential (CAP) responses, which reflect cochlear nerve activity, or distortion product otoacoustic emissions, which reflect outer hair cell integrity. However, intracochlear TNF-α perfusion reduced CAP amplitudes and increased the number of inner hair cell synapses without paired post-synaptic terminals, suggesting a pattern of synaptic degeneration that resembles that observed in primary cochlear neuropathy. Additionally, etanercept, a TNF-α blocker, protected against TNF-α-induced synaptopathy when administered systemically prior to intracochlear TNF-α perfusion. Findings motivate further investigation into the harmful effects of chronically elevated intracochlear levels of TNF-α, and the potential for etanercept to counter these effects.

    View details for DOI 10.3389/fneur.2019.01353

    View details for Web of Science ID 000517310700001

    View details for PubMedID 32116980

    View details for PubMedCentralID PMC7025643

  • Cytokine Levels in Inner Ear Fluid of Young and Aged Mice as Molecular Biomarkers of Noise-Induced Hearing Loss FRONTIERS IN NEUROLOGY Landegger, L. D., Vasilijic, S., Fujita, T., Soares, V. Y., Seist, R., Xu, L., Stankovic, K. M. 2019; 10: 977


    Sensorineural hearing loss (SNHL) is the most common sensory deficit worldwide, frequently caused by noise trauma and aging, with inflammation being implicated in both pathologies. Here, we provide the first direct measurements of proinflammatory cytokines in inner ear fluid, perilymph, of adolescent and 2-year-old mice. The perilymph of adolescent mice exposed to the noise intensity resulting in permanent auditory threshold elevations had significantly increased levels of IL-6, TNF-α, and CXCL1 6 h after exposure, with CXCL1 levels being most elevated (19.3 ± 6.2 fold). We next provide the first immunohistochemical localization of CXCL1 in specific cochlear supporting cells, and its presumed receptor, Duffy antigen receptor for chemokines (DARC), in hair cells and spiral ganglion neurons. Our results demonstrate the feasibility of molecular diagnostics of SNHL using only 0.5 μL of perilymph, and motivate future sub-μL based diagnostics of human SNHL based on liquid biopsy of the inner ear to guide therapy, promote hearing protection, and monitor response to treatment.

    View details for DOI 10.3389/fneur.2019.00977

    View details for Web of Science ID 000485185600001

    View details for PubMedID 31632328

    View details for PubMedCentralID PMC6749100

  • Gene Therapy for Human Sensorineural Hearing Loss FRONTIERS IN CELLULAR NEUROSCIENCE Ren, Y., Landegger, L. D., Stankovic, K. M. 2019; 13: 323


    Hearing loss is the most common sensory impairment in humans and currently disables 466 million people across the world. Congenital deafness affects at least 1 in 500 newborns, and over 50% are hereditary in nature. To date, existing pharmacologic therapies for genetic and acquired etiologies of deafness are severely limited. With the advent of modern sequencing technologies, there is a vast compendium of growing genetic alterations that underlie human hearing loss, which can be targeted by therapeutics such as gene therapy. Recently, there has been tremendous progress in the development of gene therapy vectors to treat sensorineural hearing loss (SNHL) in animal models in vivo. Nevertheless, significant hurdles remain before such technologies can be translated toward clinical use. These include addressing the blood-labyrinth barrier, engineering more specific and effective delivery vehicles, improving surgical access, and validating novel targets. In this review, we both highlight recent progress and outline challenges associated with in vivo gene therapy for human SNHL.

    View details for DOI 10.3389/fncel.2019.00323

    View details for Web of Science ID 000475960300001

    View details for PubMedID 31379508

    View details for PubMedCentralID PMC6660246

  • Optimized Surgical Approach Leads to Highly Efficient AAV Gene Transfer to Inner Hair Cells in Rhesus Macaque Andres-Mateos, E., Landegger, L. D., Unzu, C., Phillips, J., Lin, B., Dewyer, N. A., Sanmiguel, J., Nicolaou, F., Valero, M. D., Bourdeu, K. I., Sewell, W. F., Beiler, R. J., Beiler, R. J., McKenna, M. J., Stankovic, K. M., Vandenberghe, L. H. CELL PRESS. 2019: 318
  • A cerebellopontine angle mouse model for the investigation of tumor biology, hearing, and neurological function in NF2-related vestibular schwannoma. Nature protocols Chen, J., Landegger, L. D., Sun, Y., Ren, J., Maimon, N., Wu, L., Ng, M. R., Chen, J. W., Zhang, N., Zhao, Y., Gao, X., Fujita, T., Roberge, S., Huang, P., Jain, R. K., Plotkin, S. R., Stankovic, K. M., Xu, L. 2019; 14 (2): 541-555


    Neurofibromatosis type II (NF2) is a disease that lacks effective therapies. NF2 is characterized by bilateral vestibular schwannomas (VSs) that cause progressive and debilitating hearing loss, leading to social isolation and increased rates of depression. A major limitation in NF2 basic and translational research is the lack of animal models that allow the full spectrum of research into the biology and molecular mechanisms of NF2 tumor progression, as well as the effects on neurological function. In this protocol, we describe how to inject schwannoma cells into the mouse brain cerebellopontine angle (CPA) region. We also describe how to apply state-of-the-art intravital imaging and hearing assessment techniques to study tumor growth and hearing loss. In addition, ataxia, angiogenesis, and tumor-stroma interaction assays can be applied, and the model can be used to test the efficacy of novel therapeutic approaches. By studying the disease from every angle, this model offers the potential to unravel the basic biological underpinnings of NF2 and to develop novel therapeutics to control this devastating disease. Our protocol can be adapted to study other diseases within the CPA, including meningiomas, lipomas, vascular malformations, hemangiomas, epidermoid cysts, cerebellar astrocytomas, and metastatic lesions. The entire surgical procedure takes ~45 min per mouse and allows for subsequent longitudinal imaging, as well as neurological and hearing assessment, for up to 2 months.

    View details for DOI 10.1038/s41596-018-0105-7

    View details for PubMedID 30617350

    View details for PubMedCentralID PMC6571021

  • Computational repositioning and preclinical validation of mifepristone for human vestibular schwannoma (vol 8, 5437, 2018) SCIENTIFIC REPORTS Sagers, J. E., Brown, A. S., Vasilijic, S., Lewis, R. M., Sahin, M. I., Landegger, L. D., Perlis, R. H., Kohane, I. S., Welling, D., Patel, C. J., Stankovic, K. M. 2018; 8: 17449


    A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.

    View details for DOI 10.1038/s41598-018-36016-9

    View details for Web of Science ID 000451059600001

    View details for PubMedID 30470790

    View details for PubMedCentralID PMC6251932

  • Ancestral Adeno-Associated Virus Vector Delivery of Opsins to Spiral Ganglion Neurons: Implications for Optogenetic Cochlear Implants. Molecular therapy : the journal of the American Society of Gene Therapy Duarte, M. J., Kanumuri, V. V., Landegger, L. D., Tarabichi, O., Sinha, S., Meng, X., Hight, A. E., Kozin, E. D., Stankovic, K. M., Brown, M. C., Lee, D. J. 2018; 26 (8): 1931-1939


    Optogenetics is a transformative technology based on light-sensitive microbial proteins, known as opsins, that enable precise modulation of neuronal activity with pulsed radiant energy. Optogenetics has been proposed as a means to improve auditory implant outcomes by reducing channel interaction and increasing electrode density, but the introduction of opsins into cochlear spiral ganglion neurons (SGNs) in vivo has been challenging. Here we test opsin delivery using a synthetically developed ancestral adeno-associated virus (AAV) vector called Anc80L65. Wild-type C57BL/6 mouse pups were injected via the round window of cochlea with Anc80L65 carrying opsin Chronos under the control of a CAG promoter. Following an incubation of 6-22 weeks, pulsed blue light was delivered to cochlear SGNs via a cochleosotomy approach and flexible optical fiber. Optically evoked auditory brainstem responses (oABRs) and multiunit activity in inferior colliculus (IC) were observed. Post-experiment cochlear histology demonstrated opsin expression in SGNs (mean = 74%), with an even distribution of opsin along the cochlear basal/apical gradient. This study is the first to describe robust SGN transduction, opsin expression, and optically evoked auditory electrophysiology in neonatal mice. Ultimately, this work may provide the basis for a new generation of cochlear implant based on light.

    View details for DOI 10.1016/j.ymthe.2018.05.023

    View details for PubMedID 30017876

    View details for PubMedCentralID PMC6094394

  • Computational repositioning and preclinical validation of mifepristone for human vestibular schwannoma SCIENTIFIC REPORTS Sagers, J. E., Brown, A. S., Vasilijic, S., Lewis, R. M., Sahin, M. I., Landegger, L. D., Perlis, R. H., Kohane, I. S., Welling, D., Patel, C. J., Stankovic, K. M. 2018; 8: 5437


    The computational repositioning of existing drugs represents an appealing avenue for identifying effective compounds to treat diseases with no FDA-approved pharmacotherapies. Here we present the largest meta-analysis to date of differential gene expression in human vestibular schwannoma (VS), a debilitating intracranial tumor, and use these data to inform the first application of algorithm-based drug repositioning for this tumor class. We apply an open-source computational drug repositioning platform to gene expression data from 80 patient tumors and identify eight promising FDA-approved drugs with potential for repurposing in VS. Of these eight, mifepristone, a progesterone and glucocorticoid receptor antagonist, consistently and adversely affects the morphology, metabolic activity, and proliferation of primary human VS cells and HEI-193 human schwannoma cells. Mifepristone treatment reduces VS cell viability more significantly than cells derived from patient meningiomas, while healthy human Schwann cells remain unaffected. Our data recommend a Phase II clinical trial of mifepristone in VS.

    View details for DOI 10.1038/s41598-018-23609-7

    View details for Web of Science ID 000428994100030

    View details for PubMedID 29615643

    View details for PubMedCentralID PMC5882888

  • Targeting the cMET pathway augments radiation response without adverse effect on hearing in NF2 schwannoma models PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Zhao, Y., Liu, P., Zhang, N., Chen, J., Landegger, L. D., Wu, L., Zhao, F., Zhao, Y., Zhang, Y., Zhang, J., Fujita, T., Stemmer-Rachamimov, A., Ferraro, G. B., Liu, H., Muzikansky, A., Plotkin, S. R., Stankovic, K. M., Jain, R. K., Xu, L. 2018; 115 (9): E2077-E2084


    Neurofibromatosis type II (NF2) is a disease that needs new solutions. Vestibular schwannoma (VS) growth causes progressive hearing loss, and the standard treatment, including surgery and radiotherapy, can further damage the nerve. There is an urgent need to identify an adjunct therapy that, by enhancing the efficacy of radiation, can help lower the radiation dose and preserve hearing. The mechanisms underlying deafness in NF2 are still unclear. One of the major limitations in studying tumor-induced hearing loss is the lack of mouse models that allow hearing testing. Here, we developed a cerebellopontine angle (CPA) schwannoma model that faithfully recapitulates the tumor-induced hearing loss. Using this model, we discovered that cMET blockade by crizotinib (CRZ) enhanced schwannoma radiosensitivity by enhancing DNA damage, and CRZ treatment combined with low-dose radiation was as effective as high-dose radiation. CRZ treatment had no adverse effect on hearing; however, it did not affect tumor-induced hearing loss, presumably because cMET blockade did not change tumor hepatocyte growth factor (HGF) levels. This cMET gene knockdown study independently confirmed the role of the cMET pathway in mediating the effect of CRZ. Furthermore, we evaluated the translational potential of cMET blockade in human schwannomas. We found that human NF2-associated and sporadic VSs showed significantly elevated HGF expression and cMET activation compared with normal nerves, which correlated with tumor growth and cyst formation. Using organoid brain slice culture, cMET blockade inhibited the growth of patient-derived schwannomas. Our findings provide the rationale and necessary data for the clinical translation of combined cMET blockade with radiation therapy in patients with NF2.

    View details for DOI 10.1073/pnas.1719966115

    View details for Web of Science ID 000426152500021

    View details for PubMedID 29440379

    View details for PubMedCentralID PMC5834719

  • Periostin as a Biomarker for Nasal Polyps in Chronic Rhinosinusitis OTOLARYNGOLOGY-HEAD AND NECK SURGERY Maxfield, A. Z., Landegger, L. D., Brook, C. D., Lehmann, A. E., Campbell, A. P., Bergmark, R. W., Stankovic, K. M., Metson, R. 2018; 158 (1): 181-186


    Objective Periostin is an extracellular matrix protein that is elevated in the sinonasal tissues of patients with chronic rhinosinusitis (CRS). The purpose of this study was to determine whether serum periostin could serve as a molecular biomarker of nasal polyp burden in sinonasal disease. Study Design Prospective cohort study. Setting Academic medical center. Subjects and Methods Serum periostin levels were measured by ELISA on blood samples collected from patients undergoing sinus surgery for CRS (n = 71), further stratified by phenotype as defined by nasal polyps and asthma. Results were compared with assays performed on control subjects (n = 62). Results Mean serum periostin levels were markedly elevated in patients with CRS versus controls (66.1 ng/mL [95% CI, 51.6-80.6] vs 38.7 ng/mL [95% CI, 34.4-42.9], respectively, P = .004). In addition, mean periostin levels were significantly higher in CRS patients with nasal polyps as compared with those without polyps (94.8 ng/mL [95% CI, 67.3-122.4] vs 41.1 ng/mL [95% CI, 35.2-47.0], respectively, P < .001). Periostin levels did not correlate with sex ( P = .473), smoking history ( P = .748), aspirin-exacerbated respiratory disease status ( P = .136), oral steroid use within 1 month of surgery ( P = .281), use of topical steroid nasal spray ( P = .864), or number of prior sinus operations ( P = .973). Conclusion Serum periostin appears to be a novel molecular biomarker for the presence of nasal polyps and may serve as an indicator of CRS endotypes.

    View details for DOI 10.1177/0194599817737967

    View details for Web of Science ID 000419308700029

    View details for PubMedID 29040053

  • Cochlear Dysfunction is not Common in Human Meningioma of the Internal Auditory Canal OTOLOGY & NEUROTOLOGY Landegger, L. D., Lee, J. D., Linthicum, F. H., Stankovic, K. M. 2017; 38 (10): E486-E489


    Cochlear dysfunction is not common in human meningioma of the internal auditory canal.Meningiomas arising from the cerebellopontine angle and internal auditory canal typically cause hearing loss. Cochlear dysfunction is known to contribute to sensorineural hearing loss induced by vestibular schwannoma, the most common tumor of the internal auditory canal. Detailed cochlear histopathology in meningioma has not been reported.Retrospective analysis of cochlear histopathology in five unoperated and five operated meningiomas of the internal auditory canal identified after screening human temporal bone collections from three academic medical centers.While some dysfunction of all analyzed cochlear cell types was identified, a predominant or exclusive loss of hair cells was not observed in any meningioma. Only 14.3% of temporal bones showed significantly more hair cell damage on the side of the tumor when compared with the contralateral ear; cochlear neuronal damage was more prevalent in meningiomas. The incidence of hydrops, perilymphatic precipitate, or endolymphatic precipitate was low.Substantial cochlear damage in human meningioma of the internal auditory canal is not common. This may explain the anecdotal hearing improvement observed after surgical resection of meningioma. Our findings underline the importance of developing therapeutic strategies to prevent cochlear neuronal degeneration due to tumors of the internal auditory canal.

    View details for DOI 10.1097/MAO.0000000000001582

    View details for Web of Science ID 000425284200015

    View details for PubMedID 28984808

    View details for PubMedCentralID PMC8106507

  • Temporal bone computed tomography findings associated with feasibility of endoscopic ear surgery AMERICAN JOURNAL OF OTOLARYNGOLOGY Abdul-Aziz, D., Kozin, E. D., Lin, B. M., Wong, K., Shah, P. V., Remenschneider, A. K., Landegger, L. D., Juliano, A. F., Cohen, M. S., Lee, D. J. 2017; 38 (6): 698-703


    There are no formal radiologic criteria to stratify patients for transcanal (TEES) or transmastoid endoscopic ear surgery for resection of cholesteatoma. We aim to determine 1) whether standard preoperative computed tomography (CT) findings are associated with the need for conversion to a transmastoid approach and 2) the amount of time added for conversion from TEES to transmastoid techniques.Retrospective chart review of consecutive pediatric and adult cases of TEES for primary cholesteatoma from 2013 through 2015 (n=52). TEES cases were defined as endoscope-only procedures that did not require a transmastoid approach (n=33). Conversion cases were defined as procedures that began as TEES however, required conversion to a transmastoid approach due to the inability to complete cholesteatoma removal (n=19). Preoperative CT findings and total operating room (OR) times of TEES and conversion cases were compared.Preoperative CT scan characteristics that were associated with conversion included tegmen erosion (p=0.026), malleus erosion (p<0.001), incus erosion (p=0.009), mastoid opacification (p=0.009), soft tissue opacification extending into the aditus ad antrum (p=0.009) and into antrum (p=0.006). Total OR time for TEES cases was significantly shorter than conversion cases (median 143min versus 217min, p<0.001).Preoperative CT findings, notably extension of soft tissue in the aditus ad antrum, antrum and mastoid, are associated with need for conversion to transmastoid technique to achieve removal of cholesteatoma. Endoscope-only cases were significantly faster than cases that required conversion to a transmastoid approach.

    View details for DOI 10.1016/j.amjoto.2017.06.007

    View details for Web of Science ID 000416614800011

    View details for PubMedID 28711236

  • Tumor-Penetrating Delivery of siRNA against TNFα to Human Vestibular Schwannomas. Scientific reports Ren, Y., Sagers, J. E., Landegger, L. D., Bhatia, S. N., Stankovic, K. M. 2017; 7 (1): 12922


    Vestibular schwannoma (VS) is the most common tumor of the cerebellopontine angle, and it typically presents with sensorineural hearing loss. The genomic landscape of schwannoma is complex and many of the molecules implicated in VS pathogenesis represent targets not amenable to antibody-based or small molecule therapeutics. Tumor-targeted delivery of small interfering RNA (siRNA) therapeutics provides a direct and effective means to interrogate targets while minimizing off-target effects. To establish a preclinical model for therapeutic inhibition of putative targets in VS, archived tumor specimens, fresh tumor cells derived from patients with sporadic VS, and an established schwannoma cell line were screened. Nanoparticles directed by the tumor-homing peptide iRGD were selectively taken up by primary VS cultures in vitro via interactions with αvβ3/β5 integrins and neuropilin-1 (NRP-1). Cellular uptake was inhibited by a neutralizing antibody against αv integrin in a dose-dependent manner. When applied to primary VS cultures, iRGD-targeted nanoparticles delivered siRNA directed against TNFα in a receptor-specific fashion to potently silence gene expression and protein secretion. Taken together, our results provide a proof of principle for tumor-targeted, nanoparticle-mediated delivery of siRNA to VS and establish a novel platform for the development and pre-clinical screening of molecular therapeutics against VS.

    View details for DOI 10.1038/s41598-017-13032-9

    View details for PubMedID 29018206

    View details for PubMedCentralID PMC5635039

  • Human Cochlear Histopathology Reflects Clinical Signatures of Primary Neural Degeneration SCIENTIFIC REPORTS Sagers, J. E., Landegger, L. D., Worthington, S., Nadol, J. B., Stankovic, K. M. 2017; 7: 4884


    Auditory neuropathy is a significant and understudied cause of human hearing loss, diagnosed in patients who demonstrate abnormal function of the cochlear nerve despite typical function of sensory cells. Because the human inner ear cannot be visualized during life, histopathological analysis of autopsy specimens is critical to understanding the cellular mechanisms underlying this pathology. Here we present statistical models of severe primary neuronal degeneration and its relationship to pure tone audiometric thresholds and word recognition scores in comparison to age-matched control patients, spanning every decade of life. Analysis of 30 ears from 23 patients shows that severe neuronal loss correlates with elevated audiometric thresholds and poor word recognition. For each ten percent increase in total neuronal loss, average thresholds across patients at each audiometric test frequency increase by 6.0 dB hearing level (HL). As neuronal loss increases, threshold elevation proceeds more rapidly in low audiometric test frequencies than in high frequencies. Pure tone average closely agrees with word recognition scores in the case of severe neural pathology. Histopathologic study of the human inner ear continues to emphasize the need for non- or minimally invasive clinical tools capable of establishing cellular-level diagnoses.

    View details for DOI 10.1038/s41598-017-04899-9

    View details for Web of Science ID 000404970900046

    View details for PubMedID 28687782

    View details for PubMedCentralID PMC5501826

  • Neonatal Murine Cochlear Explant Technique as an In Vitro Screening Tool in Hearing Research. Journal of visualized experiments : JoVE Landegger, L. D., Dilwali, S., Stankovic, K. M. 2017


    While there have been remarkable advances in hearing research over the past few decades, there is still no cure for Sensorineural Hearing Loss (SNHL), a condition that typically involves damage to or loss of the delicate mechanosensory structures of the inner ear. Sophisticated in vitro and ex vivo assays have emerged in recent years, enabling the screening of an increasing number of potentially therapeutic compounds while minimizing resources and accelerating efforts to develop cures for SNHL. Though homogenous cultures of certain cell types continue to play an important role in current research, many scientists now rely on more complex organotypic cultures of murine inner ears, also known as cochlear explants. The preservation of organized cellular structures within the inner ear facilitates the in situ evaluation of various components of the cochlear infrastructure, including inner and outer hair cells, spiral ganglion neurons, neurites, and supporting cells. Here we present the preparation, culture, treatment, and immunostaining of neonatal murine cochlear explants. The careful preparation of these explants facilitates the identification of mechanisms that contribute to SNHL and constitutes a valuable tool for the hearing research community.

    View details for DOI 10.3791/55704

    View details for PubMedID 28654047

    View details for PubMedCentralID PMC5608349

  • A Unified Methodological Framework for Vestibular Schwannoma Research JOVE-JOURNAL OF VISUALIZED EXPERIMENTS Landegger, L. D., Sagers, J. E., Dilwali, S., Fujita, T., Sahin, M. I., Stankovic, K. M. 2017


    Vestibular schwannomas are the most common neoplasms of the cerebellopontine angle, making up 6-8% percent of all intracranial growths. Though these tumors cause sensorineural hearing loss in up to 95% of affected individuals, the molecular mechanisms underlying this hearing loss remain elusive. This article outlines the steps established in our laboratory to facilitate the collection and processing of various primary human tissue samples for downstream research applications integral to the study of vestibular schwannomas. Specifically, this work describes a unified methodological framework for the collection, processing, and culture of Schwann and schwannoma cells from surgical samples. This is integrated with parallel processing steps now considered essential for current research: the collection of tumor and nerve secretions, the preservation of RNA and the extraction of protein from collected tissues, the fixation of tissue for the preparation of sections, and the exposure of primary human cells to adeno-associated viruses for application to gene therapy. Additionally, this work highlights the translabyrinthine surgical approach to collect this tumor as a unique opportunity to obtain human sensory epithelium from the inner ear and perilymph. Tips to improve experimental quality are provided and common pitfalls highlighted.

    View details for DOI 10.3791/55827

    View details for Web of Science ID 000415751100017

    View details for PubMedID 28654042

    View details for PubMedCentralID PMC5608471

  • A synthetic AAV vector enables safe and efficient gene transfer to the mammalian inner ear NATURE BIOTECHNOLOGY Landegger, L. D., Pan, B., Askew, C., Wassmer, S. J., Gluck, S. D., Galvin, A., Taylor, R., Forge, A., Stankovic, K. M., Holt, J. R., Vandenberghe, L. H. 2017; 35 (3): 280-+


    Efforts to develop gene therapies for hearing loss have been hampered by the lack of safe, efficient, and clinically relevant delivery modalities. Here we demonstrate the safety and efficiency of Anc80L65, a rationally designed synthetic vector, for transgene delivery to the mouse cochlea. Ex vivo transduction of mouse organotypic explants identified Anc80L65 from a set of other adeno-associated virus (AAV) vectors as a potent vector for the cochlear cell targets. Round window membrane injection resulted in highly efficient transduction of inner and outer hair cells in mice, a substantial improvement over conventional AAV vectors. Anc80L65 round window injection was well tolerated, as indicated by sensory cell function, hearing and vestibular function, and immunologic parameters. The ability of Anc80L65 to target outer hair cells at high rates, a requirement for restoration of complex auditory function, may enable future gene therapies for hearing and balance disorders.

    View details for DOI 10.1038/nbt.3781

    View details for Web of Science ID 000395924600027

    View details for PubMedID 28165475

    View details for PubMedCentralID PMC5340646

  • Relationship between Surgically Treated Superior Canal Dehiscence Syndrome and Body Mass Index. Otolaryngology--head and neck surgery : official journal of American Academy of Otolaryngology-Head and Neck Surgery Jan, T. A., Cheng, Y. S., Landegger, L. D., Lin, B. M., Srikanth, P., Niesten, M. E., Lee, D. J. 2017: 194599816686563-?


    Objective Examine the association between body mass index (BMI) and superior canal dehiscence (SCD) among patients who have undergone surgical repair for superior canal dehiscence. Study Design Retrospective comparison study. Setting Neurotology tertiary care center. Subjects and Methods Retrospective review of consecutive adult patients evaluated at our institution for SCD syndrome between November 2006 and August 2015. A control group who underwent imaging within the same period for reasons other than SCD was also included. Patient demographics, weight, and height were examined. We performed multiple subgroup analyses to investigate the relationship of BMI, surgery vs no surgery, and correlation between patient BMI and SCD size. Results Of the 268 patients with SCD, 99 underwent surgery; 96 of these patients had complete medical records and were eligible for inclusion. Eighty-eight patients were noted to have arcuate eminence defects, and the mean BMI of this surgical cohort was 28.09 ± 5.26 kg/m(2). Nonsurgically treated patients with SCD with available data (n = 94) had a mean BMI of 27.97 ± 6.95 kg/m(2). A control group of 204 patients who underwent computed tomography for non-SCD-related causes was analyzed, of whom 155 had available data with a mean BMI of 27.91 ± 6.38 kg/m(2). Conclusion We demonstrate that adult patients who undergo surgery for SCD are not obese (mean BMI <30), and size of dehiscence poorly correlates with BMI. Our observations call into question the proposed theory that patient weight is a risk factor for the development of symptomatic SCD involving the arcuate eminence.

    View details for DOI 10.1177/0194599816686563

    View details for PubMedID 28116976

  • Effects of sustained release dexamethasone hydrogels in hearing preservation cochlear implantation. Hearing research Honeder, C., Zhu, C., Schöpper, H., Gausterer, J. C., Walter, M., Landegger, L. D., Saidov, N., Riss, D., Plasenzotti, R., Gabor, F., Arnoldner, C. 2016; 341: 43-49


    It has been shown that glucocorticoids reduce the hearing threshold shifts associated with cochlear implantation. Previous studies evaluated the administration of glucocorticoids immediately before surgery or the repeated pre- or perioperative systemic application of glucocorticoids. The aim of this study was to evaluate the effects of a sustained release dexamethasone hydrogel in hearing preservation cochlear implantation. To address this issue, a guinea pig model of cochlear implantation was used. 30 normal hearing pigmented guinea pigs were randomized into a group receiving a single dose of a dexamethasone/poloxamer407 hydrogel one day prior to surgery, a second group receiving the hydrogel seven days prior to surgery and a control group. A silicone cochlear implant electrode designed for the use in guinea pigs was inserted to a depth of 5 mm through a cochleostomy. Compound action potentials of the auditory nerve (frequency range 0.5-32 kHz) were measured preoperatively, directly postoperatively and on postoperative days 3, 7, 14, 21 and 28. Following the last audiometry, temporal bones were harvested and histologically evaluated. Dexamethasone hydrogel application one day prior to surgery resulted in significantly reduced hearing threshold shifts at low, middle and high frequencies measured at postoperative day 28 (p < 0.05). Application of the hydrogel seven days prior to surgery did not show such an effect. Dexamethasone application one day prior to surgery resulted in increased outer hair cell counts in the cochlear apex and in reduced spiral ganglion cell counts in the basal and middle turn of the cochlea, a finding that was associated with a higher rate of electrode translocation in this group. In this study, we were able to demonstrate functional benefits of a single preoperative intratympanic application of a sustained release dexamethasone hydrogel in a guinea pig model of cochlear implantation.

    View details for DOI 10.1016/j.heares.2016.08.001

    View details for PubMedID 27519654

  • Extracellular vesicles derived from human vestibular schwannomas associated with poor hearing damage cochlear cells NEURO-ONCOLOGY Soares, V. R., Atai, N. A., Fujita, T., Dilwali, S., Sivaraman, S., Landegger, L. D., Hochberg, F. H., Oliveira, C. C., Bahmad, F., Breakefield, X. O., Stankovic, K. M. 2016; 18 (11): 1498-1507


    Vestibular schwannoma (VS) is a tumor of the vestibular nerve that transmits balance information from the inner ear to the brain. Sensorineural hearing loss occurs in 95% of patients with these tumors, but the cause of this loss is not well understood. We posit a role of VS-secreted extracellular vesicles (EVs) as a major contributing factor in cochlear nerve damage.Using differential centrifugation, we isolated EVs from VS cell line HEI-193 and primary cultured human VS cells from patients with good hearing or poor hearing. The EVs were characterized using a Nanosight device and transmission electron microscopy and by extracting their RNA content. The EVs' effects on cultured murine spiral ganglion cells and organotypic cochlear cultures were studied using a transwell dual-culture system and by direct labeling of EVs with PKH-67 dye. EV-induced changes in cochlear cells were quantified using confocal immunohistochemistry. Transfection of VS cells with a green fluorescent protein-containing plasmid was confirmed with reverse transcription PCR.Human VS cells, from patients with poor hearing, produced EVs that could damage both cultured murine cochlear sensory cells and neurons. In contrast, EVs derived from VS cells from patients with good hearing did not damage the cultured cochlear cells.This is the first report on EVs derived from VSs and on the capacity of EVs from VSs from patients with hearing loss to selectively damage cochlear cells, thereby identifying a potential novel mechanism of VS-associated sensorineural hearing loss.

    View details for DOI 10.1093/neuonc/now099

    View details for Web of Science ID 000387330300006

    View details for PubMedID 27194145

    View details for PubMedCentralID PMC5063517

  • Use of the flexible fiber CO<sub>2</sub> laser in pediatric transcanal endoscopic middle ear surgery INTERNATIONAL JOURNAL OF PEDIATRIC OTORHINOLARYNGOLOGY Landegger, L. D., Cohen, M. S. 2016; 85: 154-157


    We describe 4 pediatric patients (age 6-11 years) who underwent transcanal endoscopic ear surgery (TEES) with the assistance of a flexible fiber CO2 laser over a period of 6 months. Three of these individuals suffered from densely adherent cholesteatoma, where the laser permitted one-handed dissection while preserving endoscopic visualization by limiting bleeding. In the fourth patient, TEES ossiculoplasty was performed for a congenital stapes bar, with subsequent hearing improvement. Advantages and disadvantages of the flexible fiber CO2 laser in the setting of TEES are discussed. Use of the flexible fiber CO2 laser was found to expand the TEES toolkit.

    View details for DOI 10.1016/j.ijporl.2016.03.039

    View details for Web of Science ID 000378185000030

    View details for PubMedID 27240515

  • Noise trauma and systemic application of the selective glucocorticoid receptor modulator compound A. Journal of negative results in biomedicine Landegger, L. D., Honeder, C., Zhu, C., Schöpper, H., Engleder, E., Gabor, F., Gstoettner, W., Arnoldner, C. 2016; 15: 10


    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).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.Relative to the control treatments, Compound A failed to preserve auditory thresholds post-noise exposure with statistical significance. Histological analyses confirm the physiological result.The present findings suggest that Compound A does not have substantial otoprotective capacities in a noise trauma model.

    View details for DOI 10.1186/s12952-016-0053-0

    View details for PubMedID 27164957

    View details for PubMedCentralID PMC4863352

  • Novel Synthetic AAV Efficiently Transduces Neurosensory Hair Cells in the Cochlea Landegger, L., Pang, B., Wassmer, S., Gluck, S., Galvin, A., Stankovic, K. M., Holt, J. R., Vandenberghe, L. H. NATURE PUBLISHING GROUP. 2016: S107
  • Human audiometric thresholds do not predict specific cellular damage in the inner ear HEARING RESEARCH Landegger, L. D., Psaltis, D., Stankovic, K. M. 2016; 335: 83-93


    As otology enters the field of gene therapy and human studies commence, the question arises whether audiograms - the current gold standard for the evaluation of hearing function - can consistently predict cellular damage within the human inner ear and thus should be used to define inclusion criteria for trials. Current assumptions rely on the analysis of small groups of human temporal bones post mortem or from psychophysical identification of cochlear "dead regions" in vivo, but a comprehensive study assessing the correlation between audiometric thresholds and cellular damage within the cochlea is lacking.A total of 131 human temporal bones from 85 adult individuals (ages 19-92 years, median 69 years) with sensorineural hearing loss due to various etiologies were analyzed. Cytocochleograms - which quantify loss of hair cells, neurons, and strial atrophy along the length of the cochlea - were compared with subjects' latest available audiometric tests prior to death (time range 5 h-22 years, median 24 months). The Greenwood function and the equivalent rectangular bandwidth were used to infer, from cytocochleograms, cochlear locations corresponding to frequencies tested in clinical audiograms. Correlation between audiometric thresholds at clinically tested frequencies and cell type-specific damage in those frequency regions was examined by calculating Spearman's correlation coefficients.Similar audiometric profiles reflected widely different cellular damage in the cochlea. In our diverse group of patients, audiometric thresholds tended to be more influenced by hair cell loss than by neuronal loss or strial atrophy. Spearman's correlation coefficient across frequencies was at most 0.7 and often below 0.5, with 1.0 indicating perfect correlation.Audiometric thresholds do not predict specific cellular damage in the human inner ear. Our study highlights the need for better non- or minimally-invasive tools, such as cochlear endoscopy, to establish cellular-level diagnosis and thereby guide therapy and monitor response to treatment.

    View details for DOI 10.1016/j.heares.2016.02.018

    View details for Web of Science ID 000376713900011

    View details for PubMedID 26924453

    View details for PubMedCentralID PMC5970796

  • Pediatric endoscopic ear surgery in clinical practice: Lessons learned and early outcomes LARYNGOSCOPE Cohen, M. S., Landegger, L. D., Kozin, E. D., Lee, D. J. 2016; 126 (3): 732-738


    Only a few reports describe the outcomes following endoscopic ear surgery (EES) in children for chronic ear disease. We differentiate between transcanal endoscopic ear surgery (TEES), where the case is performed with only endoscopic visualization, from non-TEES, where the endoscope is not used at all or used as an adjunct to the microscope. We hypothesize that EES is an effective approach to manage middle ear pathology using a transcanal approach in most cases, and can be incorporated into a pediatric otology practice with a neutral or positive effect on outcomes. Lessons learned during this process are analyzed and discussed.Single-institution, retrospective chart review of outcomes following TEES and non-TEES in children from January 1, 2013 through July 1, 2014.Procedures included tympanoplasty, ossiculoplasty, and cholesteatoma resection. Primary outcome measures included closure rate of tympanic membrane perforations, audiometric outcomes, and complications. Surgical times were reported as secondary measures.Ninety-four patients underwent 121 middle ear procedures. TEES was performed in 51/121 of cases (42.1%). Comparison of TEES versus non-TEES cases showed no significant difference in rate of tympanoplasty closure (P > .99). The mean pure-tone improvement following TEES tympanoplasty was -7.8 dB versus -1.33 dB for non-TEES cases (P = .03). Surgical times were similar between groups.EES techniques were readily incorporated into a pediatric otology practice. A standardized EES classification system is useful for analyzing utilization patterns and results across institutions. Tympanic membrane closure rates and hearing outcomes were similar in TEES and non-TEES cases.4. Laryngoscope, 126:732-738, 2016.

    View details for DOI 10.1002/lary.25410

    View details for Web of Science ID 000371242800046

    View details for PubMedID 26228434

  • Secreted Factors from Human Vestibular Schwannomas Can Cause Cochlear Damage SCIENTIFIC REPORTS Dilwali, S., Landegger, L. D., Soares, V. R., Deschler, D. G., Stankovic, K. M. 2015; 5: 18599


    Vestibular schwannomas (VSs) are the most common tumours of the cerebellopontine angle. Ninety-five percent of people with VS present with sensorineural hearing loss (SNHL); the mechanism of this SNHL is currently unknown. To establish the first model to study the role of VS-secreted factors in causing SNHL, murine cochlear explant cultures were treated with human tumour secretions from thirteen different unilateral, sporadic VSs of subjects demonstrating varied degrees of ipsilateral SNHL. The extent of cochlear explant damage due to secretion application roughly correlated with the subjects' degree of SNHL. Secretions from tumours associated with most substantial SNHL resulted in most significant hair cell loss and neuronal fibre disorganization. Secretions from VSs associated with good hearing or from healthy human nerves led to either no effect or solely fibre disorganization. Our results are the first to demonstrate that secreted factors from VSs can lead to cochlear damage. Further, we identified tumour necrosis factor alpha (TNFα) as an ototoxic molecule and fibroblast growth factor 2 (FGF2) as an otoprotective molecule in VS secretions. Antibody-mediated TNFα neutralization in VS secretions partially prevented hair cell loss due to the secretions. Taken together, we have identified a new mechanism responsible for SNHL due to VSs.

    View details for DOI 10.1038/srep18599

    View details for Web of Science ID 000367032600001

    View details for PubMedID 26690506

    View details for PubMedCentralID PMC4686978

  • Preclinical validation of anti-nuclear factor-kappa B therapy to inhibit human vestibular schwannoma growth MOLECULAR ONCOLOGY Dilwali, S., Briet, M. C., Kao, S., Fujita, T., Landegger, L. D., Platt, M. P., Stankovic, K. M. 2015; 9 (7): 1359-1370


    Vestibular schwannomas (VSs), the most common tumors of the cerebellopontine angle, arise from Schwann cells lining the vestibular nerve. Pharmacotherapies against VS are almost non-existent. Although the therapeutic inhibition of inflammatory modulators has been established for other neoplasms, it has not been explored in VS. A bioinformatic network analysis of all genes reported to be differentially expressed in human VS revealed a pro-inflammatory transcription factor nuclear factor-kappa B (NF-κB) as a central molecule in VS pathobiology. Assessed at the transcriptional and translational level, canonical NF-κB complex was aberrantly activated in human VS and derived VS cultures in comparison to control nerves and Schwann cells, respectively. Cultured primary VS cells and VS-derived human cell line HEI-193 were treated with specific NF-κB siRNAs, experimental NF-κB inhibitor BAY11-7082 (BAY11) and clinically relevant NF-κB inhibitor curcumin. Healthy human control Schwann cells from the great auricular nerve were also treated with BAY11 and curcumin to assess toxicity. All three treatments significantly reduced proliferation in primary VS cultures and HEI-193 cells, with siRNA, 5 μM BAY11 and 50 μM curcumin reducing average proliferation (±standard error of mean) to 62.33% ± 10.59%, 14.3 ± 9.7%, and 23.0 ± 20.9% of control primary VS cells, respectively. These treatments also induced substantial cell death. Curcumin, unlike BAY11, also affected primary Schwann cells. This work highlights NF-κB as a key modulator in VS cell proliferation and survival and demonstrates therapeutic efficacy of directly targeting NF-κB in VS.

    View details for DOI 10.1016/j.molonc.2015.03.009

    View details for Web of Science ID 000359884800011

    View details for PubMedID 25891780

    View details for PubMedCentralID PMC4523465

  • Nonsteroidal anti-inflammatory medications are cytostatic against human vestibular schwannomas. Translational research : the journal of laboratory and clinical medicine Dilwali, S., Kao, S. Y., Fujita, T., Landegger, L. D., Stankovic, K. M. 2015; 166 (1): 1-11


    Vestibular schwannomas (VSs) are the most common tumors of the cerebellopontine angle. Significant clinical need exists for pharmacotherapies against VSs. Motivated by previous findings that immunohistochemical expression of cyclooxygenase 2 (COX-2) correlates with VS growth rate, we investigated the role of COX-2 in VSs and tested COX-2 inhibiting salicylates against VSs. COX-2 was found to be aberrantly expressed in human VS and primary human VS cells in comparison with control human nerve specimens and primary Schwann cells (SCs), respectively. Furthermore, levels of prostaglandin E2, the downstream enzymatic product of COX-2, were correlated with primary VS culture proliferation rate. Because COX-2 inhibiting salicylates such as aspirin are well tolerated and frequently clinically used, we assessed their repurposing for VS. Changes in proliferation, cell death, and cell viability were analyzed in primary VS cultures treated with aspirin, sodium salicylate, or 5-aminosalicylic acid. These drugs neither increased VS cell death nor affected healthy SCs. The cytostatic effect of aspirin in vitro was in concurrence with our previous clinical finding that patients with VS taking aspirin demonstrate reduced tumor growth. Overall, this work suggests that COX-2 is a key modulator in VS cell proliferation and survival and highlights salicylates as promising pharmacotherapies against VS.

    View details for DOI 10.1016/j.trsl.2014.12.007

    View details for PubMedID 25616959

    View details for PubMedCentralID PMC4458444

  • Systematic Review of Outcomes Following Observational and Operative Endoscopic Middle Ear Surgery LARYNGOSCOPE Kozin, E. D., Gulati, S., Kaplan, A. B., Lehmann, A. E., Remenschneider, A. K., Landegger, L. D., Cohen, M. S., Lee, D. J. 2015; 125 (5): 1205-1214


    Middle ear surgery increasingly employs endoscopes as an adjunct to or replacement for the operative microscope. We provide a systematic review of endoscope applications in middle ear surgery with an emphasis on outcomes, including the need for conversion to microscope, audiometric findings, length of follow-up, as well as disease-specific outcomes.PubMed, Embase, and Cochrane CENTRAL database.A literature review was performed using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis recommendations. Articles were categorized based on study design, indication, and use of an endoscope either as an adjunct to or as a replacement for a microscope. Qualitative and descriptive analyses of studies and outcomes data were performed.One-hundred three articles met inclusion and exclusion criteria. Of the identified articles, 38 provided outcomes data. The majority of these studies were moderate quality, retrospective, case-series reports. The indications for use of the endoscope were broad, with the most common being resection of cholesteatoma. In cholesteatoma surgery, endoscope approaches routinely identified residual cholesteatoma in primary and second-look cases. Other outcomes, including robust audiometric data, operating room times, wound healing, and quality of life surveys were not well described.Endoscopes have consistently been used as an adjunct to the microscope to improve visualization of the tympanic cavity. Recent reports utilize the endoscope exclusively during surgical dissection; however, data comparing patient outcomes following the use of an endoscope to a microscope are lacking. Areas in need of additional research are highlighted.NA

    View details for DOI 10.1002/lary.25048

    View details for Web of Science ID 000353996900040

    View details for PubMedID 25418475

    View details for PubMedCentralID PMC4467784

  • Effects of intraoperatively applied glucocorticoid hydrogels on residual hearing and foreign body reaction in a guinea pig model of cochlear implantation. Acta oto-laryngologica Honeder, C., Landegger, L. D., Engleder, E., Gabor, F., Plasenzotti, R., Plenk, H., Kaider, A., Hirtler, L., Gstoettner, W., Arnoldner, C. 2015; 135 (4): 313-9


    The intraoperative application of glucocorticoid-loaded hydrogels seems to cause a reduction in neutrophil infiltration. No beneficial effect on hearing thresholds was detected.To evaluate the application of dexamethasone- and triamcinolone acetonide-loaded hydrogels for effects on hearing preservation and foreign body reaction in a guinea pig model for cochlear implantation (CI).A total of 48 guinea pigs (n = 12 per group) were implanted with a single channel electrode and intraoperatively treated with 50 μl of a 20% w/v poloxamer 407 hydrogel loaded with 6% dexamethasone or 30% triamcinolone acetonide, a control hydrogel, or physiological saline. Click- and tone burst-evoked compound action potential thresholds were determined preoperatively and directly postoperatively as well as on days 3, 7, 14, 21, and 28. At the end of the experiment, temporal bones were prepared for histological evaluation by a grinding/polishing technique with the electrode in situ. Three ears per treatment group were serially sectioned and evaluated for histological alterations.The intratympanic application of glucocorticoid-loaded hydrogels did not improve the preservation of residual hearing in this cochlear implant model. The foreign body reaction to the electrode appeared reduced in the glucocorticoid-treated animals. No correlation was found between the histologically described trauma to the inner ear and the resulting hearing threshold shifts.

    View details for DOI 10.3109/00016489.2014.986758

    View details for PubMedID 25720453

    View details for PubMedCentralID PMC4885660

  • Evaluation of the selective glucocorticoid receptor agonist compound A for ototoxic effects. The Laryngoscope Honeder, C., Engleder, E., Schöpper, H., Krause, M., Landegger, L. D., Plasenzotti, R., Gabor, F., Gstoettner, W., Arnoldner, C. 2015; 125 (4): E149-55


    To evaluate the selective glucocorticoid receptor agonist (SEGRA) compound A, a potential novel therapeutic for inner ear disorders, for ototoxic effects.Laboratory animal study.Experimental guinea pigs were grouped as follows: Systemic application of compound A (1.5 mg/kg and 4.5 mg/kg; n = 6/group) and intratympanic application of compound A (1 mM and 10 mM; n = 6/group). Contralateral ears in topically treated animals served as controls. Hearing thresholds were determined by auditory brainstem response before and directly after the application of compound A, as well as on days 3, 7, 14, 21, and 28. At the end of the experiments, temporal bones were harvested for histological evaluation.Systemic administration of compound A (1.5 mg/kg and 4.5 mg/kg) did not cause hearing threshold shifts, whereas the intratympanic injection (1 mM and 10 mM) resulted in a hearing loss. Histological analysis of the middle and inner ears after topical compound A application showed alterations in the tympanic membranes, the auditory ossicles, and the round window membranes, whereas spiral ganglion cells and hair cells were not affected.SEGRAs such as compound A could provide novel therapeutic options for the treatment of inner ear disorders and reduce metabolic side effects. Whereas the intratympanic application of compound A resulted in a hearing loss, the systemic application of compound A merits evaluation for otoprotective effects in trauma models.

    View details for DOI 10.1002/lary.25011

    View details for PubMedID 25382757

    View details for PubMedCentralID PMC4885662