Research

THE OVERALL GOAL of our research program is to protect and regenerate the inner ear in order to improve patients’ hearing health. We strive to understand the mechanisms of development, regeneration, and protection of mammalian sensory hair cells using state-of-the-art technologies and collaborative approaches.

   

Development

Hair cells are born and then precisely organized into rows, a highly-ordered structure critical for our hearing organ to function properly. Understanding how this complex organ develops provides us with invaluable insights into how inner ear malformation relates to congenital hearing loss and also expedites our efforts in regenerating this organ. Numerous signaling pathways including Wnt signaling have been implicated to regulate these critical developmental steps.

Our group is interested in determining how Wnt signaling dictates these diverse processes and interact with other key signaling pathways. In particular, we aim to probe individual components of the pathway to determine their roles in governing sensory cell fate and planar cell polarity.

Regeneration

Regenerating the mammalian cochlea is a monumental task yet it remains our ultimate goal. Our two-pronged approach is based on our findings that the newborn mouse cochlea and utricle both regenerate lost hair cells by defined progenitors.

By interrogating the genetic landscape of cochlear and utricular hair cell progenitors, we hope to better understand mechanisms governing early phases of regeneration. Using in vitro and in vivo models of hair cell regeneration in the utricle, we aim to characterize the mechanisms and physiology of vestibular regeneration at both the cellular and organ levels.

Aminoglycoside Ototoxicity

Aminoglycosides are potent antibiotics that cause irreversible hearing loss, making aminoglycoside ototoxicity one of the most preventable causes of hearing loss. We aim to design and build a new version of antibiotic that is non-ototoxic. In a collaborative effort with Tony Ricci’s lab, we have recently generated the first generation of non-ototoxic aminoglycoside derivatives. We now focus on understanding the structural-activity relationships of these compounds by studying their interactions with bacterial ribosomes, trafficking into bacteria and hair cells, antimicrobial activities and ototoxicity. With these information, we plan to optimize the next generation of drug design and synthesis.

 

Publications

Specialty Career Advisor, Otolaryngology, Office of Medical Student Affairs (2020 - 2022) Chief, Division of Pediatric Otolaryngology (2019 - Present) Director, Stanford clinician-scientist training program (2016 - Present)

Publications

  • Microstructural Changes in the Brainstem Auditory Pathway in Children With Hearing Loss. Otology & neurotology : official publication of the American Otological Society, American Neurotology Society [and] European Academy of Otology and Neurotology Moon, P. K., Ward, K. M., Din, T. F., Saki, S., Cheng, A. G., Yeom, K. W., Ahmad, I. N. 2024; 45 (3): e170-e176

    Abstract

    To assess the utility of diffusion tensor imaging of the auditory pathway in children with sensorineural hearing loss (SNHL).Retrospective cohort study.A single academic tertiary children's hospital.Sixteen pediatric patients with bilateral SNHL of at least moderate severity in the poorer ear (eight male; mean age, 5.3 ± 4.9 yrs). Controls consisted of age- and sex-matched children with normal hearing who were imaged for nonotologic, non-neurologic medical concerns and found to have normal magnetic resonance imaging (MRI).Three Tesla MRI scanners were used for diffusion tensor imaging.Quantitative diffusion tensor metrics were extracted from the superior olivary nucleus (SON), inferior colliculus (IC), and ipsilateral fiber tracts between the SON and IC delineated by tractography.We identified differences in fractional anisotropy of the SON between the SNHL cohort and controls (0.377 ± 0.056 vs. 0.422 ± 0.052; p = 0.009), but not in the IC. There were no differences in the mean diffusivity (MD) values in the IC and SON. Among younger children (≤5 yrs), MD was decreased in the SNHL cohort compared with controls in the IC (0.918 ± 0.051 vs. 1.120 ± 0.142; p < 0.001). However, among older children (>5 yrs), there were no differences in MD (1.124 ± 0.198 vs. 0.997 ± 0.103; p = 0.119). There were no differences in MD or fractional anisotropy in the white matter fibers of the IC-SON tract.Our results suggest abnormal neural tracts along the central auditory pathway among children with SNHL. Longitudinal studies should assess the prognostic value of these MRI-based findings for assessing long-term outcomes and determining intervention efficacy.

    View details for DOI 10.1097/MAO.0000000000004129

    View details for PubMedID 38361295

  • Loss of Pax3 causes reduction of melanocytes in the developing mouse cochlea. Scientific reports Udagawa, T., Takahashi, E., Tatsumi, N., Mutai, H., Saijo, H., Kondo, Y., Atkinson, P. J., Matsunaga, T., Yoshikawa, M., Kojima, H., Okabe, M., Cheng, A. G. 2024; 14 (1): 2210

    Abstract

    Cochlear melanocytes are intermediate cells in the stria vascularis that generate endocochlear potentials required for auditory function. Human PAX3 mutations cause Waardenburg syndrome and abnormalities of skin and retinal melanocytes, manifested as congenital hearing loss (~ 70%) and hypopigmentation of skin, hair and eyes. However, the underlying mechanism of hearing loss remains unclear. Cochlear melanocytes in the stria vascularis originated from Pax3-traced melanoblasts and Plp1-traced Schwann cell precursors, both of which derive from neural crest cells. Here, using a Pax3-Cre knock-in mouse that allows lineage tracing of Pax3-expressing cells and disruption of Pax3, we found that Pax3 deficiency causes foreshortened cochlea, malformed vestibular apparatus, and neural tube defects. Lineage tracing and in situ hybridization show that Pax3+ derivatives contribute to S100+, Kir4.1+ and Dct+ melanocytes (intermediate cells) in the developing stria vascularis, all of which are significantly diminished in Pax3 mutant animals. Taken together, these results suggest that Pax3 is required for the development of neural crest cell-derived cochlear melanocytes, whose absence may contribute to congenital hearing loss of Waardenburg syndrome in humans.

    View details for DOI 10.1038/s41598-024-52629-9

    View details for PubMedID 38278860

    View details for PubMedCentralID PMC10817906

  • Hair Cell Regeneration: From Animals to Humans. Clinical and experimental otorhinolaryngology Choi, S. W., Abitbol, J., Cheng, A. 2024

    Abstract

    Cochlear hair cells are critical in converting sound into electrical signals that are relayed via the spiral ganglion neurons to the central auditory pathway. Hair cells are vulnerable to damage caused by excessive noise, aging, and ototoxic agents. Non-mammals can regenerate lost hair cells by mitotic regeneration and direct transdifferentiation of surrounding supporting cells. However, in mature mammals, damaged hair cells are not replaced, resulting in permanent hearing loss. Recent studies have uncovered mechanisms by which sensory organs in non-mammals and the neonatal mammalian cochlea regenerate hair cells, and outlined possible mechanisms why this ability declines rapidly with age in mammals. Here, we review similarities and differences between avian, zebrafish and mammalian hair cell regeneration. Moreover, we discuss advances and limitations of hair cell regeneration in the mature cochlea and their potential applications to human hearing loss.

    View details for DOI 10.21053/ceo.2023.01382

    View details for PubMedID 38271988

  • Is Public Interest Associated with Real-World Management of Ankyloglossia? Otolaryngology--head and neck surgery : official journal of American Academy of Otolaryngology-Head and Neck Surgery Naseem, D. F., Sheth, A. H., Cheng, A. G., Qian, Z. J. 2024

    Abstract

    Assess the relationship between public interest in ankyloglossia as determined by internet search volume and real-world medical claims data.Retrospective Cohort Study.This retrospective cohort study was conducted using claims data from the Merative™ Marketscan® Research Databases. The internet search data was collected from Google Trends.Annual Google Trends data were compiled using search terms associated with "ankyloglossia" and "frenotomy" for the years 2011 to 2021. We obtained incidence of ankyloglossia diagnoses and frenotomy procedures in children under 12 months from Marketscan relative to all infants enrolled. We compared associations between search and incidence data among US states and over time.Google search correlated with ankyloglossia incidence (r = 0.4104, P = .0031) and with frenotomy incidence (r = 0.4062, P = .0034) per state. Ankyloglossia diagnoses increased with Google search index (coefficient = 0.336, 95% confidence interval [CI] 0.284, 0.388) and year (coefficient = 0.028, 95% CI 0.025, 0.031). Similarly, frenotomy procedures increased with Google search index (coefficient = 0.371, 95% CI 0.313, 0.429) and year (coefficient = 0.027, 95% CI 0.024, 0.030).Associations between online ankyloglossia search trends and both diagnosis and treatment rates, persist across US regions and timeframes. Internet search trends are pivotal in shaping pediatric health care decisions, driving clinical consensus, and disseminating evidence-based information.

    View details for DOI 10.1002/ohn.643

    View details for PubMedID 38219744

  • Selection of viral capsids and promoters affects the efficacy of rescue of Tmprss3-deficient cochlea. Molecular therapy. Methods & clinical development Aaron, K. A., Pekrun, K., Atkinson, P. J., Billings, S. E., Abitbol, J. M., Lee, I. A., Eltawil, Y., Chen, Y. S., Dong, W., Nelson, R. F., Kay, M. A., Cheng, A. G. 2023; 30: 413-428

    Abstract

    Adeno-associated virus (AAV)-mediated gene transfer has shown promise in rescuing mouse models of genetic hearing loss, but how viral capsid and promoter selection affects efficacy is poorly characterized. Here, we tested combinations of AAVs and promoters to deliver Tmprss3, mutations in which are associated with hearing loss in humans. Tmprss3tm1/tm1 mice display severe cochlear hair cell degeneration, loss of auditory brainstem responses, and delayed loss of spiral ganglion neurons. Under the ubiquitous CAG promoter and AAV-KP1 capsid, Tmprss3 overexpression caused striking cytotoxicity in vitro and in vivo and failed to rescue degeneration or dysfunction of the Tmprss3tm1/tm1 cochlea. Reducing the dosage or using AAV-DJ-CAG-Tmprss3 diminished cytotoxicity without rescue of the Tmprss3tm1/tm1 cochlea. Finally, the combination of AAV-KP1 capsid and the EF1α promoter prevented cytotoxicity and reduced hair cell degeneration, loss of spiral ganglion neurons, and improved hearing thresholds in Tmprss3tm1/tm1 mice. Together, our study illustrates toxicity of exogenous genes and factors governing rescue efficiency, and suggests that cochlear gene therapy likely requires precisely targeted transgene expression.

    View details for DOI 10.1016/j.omtm.2023.08.004

    View details for PubMedID 37663645

    View details for PubMedCentralID PMC10471831

  • β-Catenin transcriptional activity is required for establishment of inner pillar cell identity during cochlear development. PLoS genetics Ebeid, M., Kishimoto, I., Roy, P., Zaidi, M. A., Cheng, A. G., Huh, S. H. 2023; 19 (8): e1010925

    Abstract

    The mammalian cochlea is composed of sensory hair cells as well as multiple different types of non-sensory supporting cells. Pillar cells are one type of supporting cell that form the tunnel of Corti and include two morphologically and functionally distinct subtypes: inner pillar cells (IPCs) and outer pillar cells (OPCs). The processes of specification and differentiation of inner versus outer pillar cells are still unclear. Here, we show that β-Catenin is required for establishing IPC identity in the mammalian cochlea. To differentiate the transcriptional and adhesion roles of β-Catenin in establishing IPC identity, we examined two different models of β-Catenin deletion; one that deletes both transcriptional and structural functions and one which retains cell adhesion function but lacks transcriptional function. Here, we show that cochleae lacking β-Catenin transcriptional function lost IPCs and displayed extranumerary OPCs, indicating its requirement for establishing IPC identity. Overexpression of β-Catenin induced proliferation within IPCs but not ectopic IPCs. Single-cell transcriptomes of supporting cells lacking β-Catenin transcriptional function show a loss of the IPC and gain of OPC signatures. Finally, targeted deletion of β-Catenin in IPCs also led to the loss of IPC identity, indicating a cell autonomous role of β-Catenin in establishing IPC identity. As IPCs have the capacity to regenerate sensory hair cells in the postnatal cochlea, our results will aid in future IPC-based hair cell regeneration strategies.

    View details for DOI 10.1371/journal.pgen.1010925

    View details for PubMedID 37639482

  • Assessment of drug permeability through an exvivo porcine round window membrane model. iScience Moatti, A., Silkstone, D., Martin, T., Abbey, K., Hutson, K. A., Fitzpatrick, D. C., Zdanski, C. J., Cheng, A. G., Ligler, F. S., Greenbaum, A. 2023; 26 (6): 106789

    Abstract

    Delivery of pharmaceutical therapeutics to the inner ear to treat and prevent hearing loss is challenging. Systemic delivery is not effective as only a small fraction of the therapeutic agent reaches the inner ear. Invasive surgeries to inject through the round window membrane (RWM) or cochleostomy may cause damage to the inner ear. An alternative approach is to administer drugs into the middle ear using an intratympanic injection, with the drugs primarily passing through the RWM to the inner ear. However, the RWM is a barrier, only permeable to a small number of molecules. To study and enhance the RWM permeability, we developed an exvivo porcine RWM model, similar in structure and thickness to the human RWM. The model is viable for days, and drug passage can be measured at multiple time points. This model provides a straightforward approach to developing effective and non-invasive delivery methods to the inner ear.

    View details for DOI 10.1016/j.isci.2023.106789

    View details for PubMedID 37213232

  • Ankyloglossia: Clinical and Sociodemographic Predictors of Diagnosis and Management in the United States, 2004 to 2019. Otolaryngology--head and neck surgery : official journal of American Academy of Otolaryngology-Head and Neck Surgery Wei, E. X., Meister, K. D., Balakrishnan, K., Cheng, A. G., Qian, Z. J. 2023

    Abstract

    OBJECTIVE: The past 2 decades have seen a rapid increase in the diagnosis of ankyloglossia. Patients are often managed by lingual frenotomy. The objective is to define the clinical and socioeconomic factors that determine which patients receive frenotomy.STUDY DESIGN: A retrospective analysis of commercially insured children.SETTING: Optum Data Mart database.METHODS: Trends in frenotomy including provider and setting were described. Multiple logistic regression was used to determine predictors of frenotomy.RESULTS: Diagnosis of ankyloglossia increased from 2004 to 2019 (from 3377 in 2004 to 13,200 in 2019), while lingual frenotomy similarly increased from 1483 in 2004 to 6213 in 2019. The proportion of inpatient frenotomy procedures increased from 6.2% to 16.6% from 2004 to 2019, with pediatricians having the highest odds of performing inpatient frenotomies (odds ratio:4.32, 95% confidence interval:4.08, 4.57). Additionally, during the study period, the proportion of frenotomies performed by pediatricians increased from 13.01% in 2004 to 28.38% in 2019. In multivariate regression analyses, frenotomy was significantly associated with the male sex, white non-Hispanic ethnicity, higher parental income and education, and a greater number of siblings.CONCLUSION: Ankyloglossia has been increasingly diagnosed in the past 2 decades, and amongpatients with ankyloglossia, frenotomy is increasingly performed. This trend was driven at least in part due to increasing rates of pediatricians as proceduralists. After accounting for maternal and patient-level clinical factors, socioeconomic differences in the management of ankyloglossia were observed.

    View details for DOI 10.1002/ohn.332

    View details for PubMedID 36994937

  • Prevalence of Cochlear Nerve Deficiency and Hearing Device Use in Children With Single-Sided Deafness OTOLARYNGOLOGY-HEAD AND NECK SURGERY Ward, K. M., Coughran, A. J., Lee, M., Fitzgerald, M. B., Cheng, A. G., Chang, K. W., Ahmad, I. N. 2023

    View details for DOI 10.1002/ohn.255

    View details for Web of Science ID 000928877200001

  • Prevalence of Cochlear Nerve Deficiency and Hearing Device Use in Children With Single-Sided Deafness. Otolaryngology--head and neck surgery : official journal of American Academy of Otolaryngology-Head and Neck Surgery Ward, K. M., Coughran, A. J., Lee, M., Fitzgerald, M. B., Cheng, A. G., Chang, K. W., Ahmad, I. N. 2023

    Abstract

    This study aimed to assess the prevalence of cochlear nerve deficiency (CND) in a cohort of pediatric patients with single-sided deafness (SSD). A secondary objective was to investigate trends in intervention and hearing device use in these children.Case series with chart review.Pediatric tertiary care center.Children ages 0 to 21 years with SSD (N = 190) who underwent computerized tomography (CT) and/or magnetic resonance imaging (MRI) were included. Diagnostic criteria for SSD included unilateral severe-to-profound sensorineural hearing loss with normal hearing sensitivity in the contralateral ear. Diagnostic criteria for CND included neuroradiologist report of an "aplastic or hypoplastic nerve" on MRI or a "stenotic cochlear aperture" on CT.The prevalence of CND was 42% for children with CT only, 76% for children with MRI only, and 63% for children with both MRI and CT. Of the children with MRI and CT, there was a 90% concordance across imaging modalities. About 36% of children with SSD had hearing devices that routed sound to the normal hearing ear (ie, bone conduction hearing device/contralateral routing of signal), while only 3% received a cochlear implant. Approximately 40% did not have a hearing device. Hearing device wear time averaged 2.9 hours per day and did not differ based on cochlear nerve status.There is a high prevalence of CND in children with SSD. Cochlear nerve status should be confirmed via MRI in children with SSD. The limited implementation and use of hearing devices observed for children with SSD reinforce the need for increased support for early and continuous intervention.

    View details for DOI 10.1002/ohn.255

    View details for PubMedID 36939463