Browsing by Author "Romano, Daniel R."

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Deafness-in-a-dish: modeling hereditary deafness with inner ear organoids
    (Springer, 2022) Romano, Daniel R.; Hashino, Eri; Nelson, Rick F.; Otolaryngology -- Head and Neck Surgery, School of Medicine
    Sensorineural hearing loss (SNHL) is a major cause of functional disability in both the developed and developing world. While hearing aids and cochlear implants provide significant benefit to many with SNHL, neither targets the cellular and molecular dysfunction that ultimately underlies SNHL. The successful development of more targeted approaches, such as growth factor, stem cell, and gene therapies, will require a yet deeper understanding of the underlying molecular mechanisms of human hearing and deafness. Unfortunately, the human inner ear cannot be biopsied without causing significant, irreversible damage to the hearing or balance organ. Thus, much of our current understanding of the cellular and molecular biology of human deafness, and of the human auditory system more broadly, has been inferred from observational and experimental studies in animal models, each of which has its own advantages and limitations. In 2013, researchers described a protocol for the generation of inner ear organoids from pluripotent stem cells (PSCs), which could serve as scalable, high-fidelity alternatives to animal models. Here, we discuss the advantages and limitations of conventional models of the human auditory system, describe the generation and characteristics of PSC-derived inner ear organoids, and discuss several strategies and recent attempts to model hereditary deafness in vitro. Finally, we suggest and discuss several focus areas for the further, intensive characterization of inner ear organoids and discuss the translational applications of these novel models of the human inner ear.
  • Thumbnail Image
    Item
    Generating high-fidelity cochlear organoids from human pluripotent stem cells
    (Elsevier, 2023) Moore, Stephen T.; Nakamura, Takashi; Nie, Jing; Solivais, Alexander J.; Aristizábal-Ramírez, Isabel; Ueda, Yoshitomo; Manikandan, Mayakannan; Reddy, V. Shweta; Romano, Daniel R.; Hoffman, John R.; Perrin, Benjamin J.; Nelson, Rick F.; Frolenkov, Gregory I.; Chuva de Sousa Lopes, Susana M.; Hashino, Eri; Otolaryngology -- Head and Neck Surgery, School of Medicine
    Mechanosensitive hair cells in the cochlea are responsible for hearing but are vulnerable to damage by genetic mutations and environmental insults. The paucity of human cochlear tissues makes it difficult to study cochlear hair cells. Organoids offer a compelling platform to study scarce tissues in vitro; however, derivation of cochlear cell types has proven non-trivial. Here, using 3D cultures of human pluripotent stem cells, we sought to replicate key differentiation cues of cochlear specification. We found that timed modulations of Sonic Hedgehog and WNT signaling promote ventral gene expression in otic progenitors. Ventralized otic progenitors subsequently give rise to elaborately patterned epithelia containing hair cells with morphology, marker expression, and functional properties consistent with both outer and inner hair cells in the cochlea. These results suggest that early morphogenic cues are sufficient to drive cochlear induction and establish an unprecedented system to model the human auditory organ.
  • Thumbnail Image
    Item
    Verbal Working Memory Error Patterns and Speech-Language Outcomes in Youth With Cochlear Implants
    (American Speech-Language-Hearing Association, 2021) Romano, Daniel R.; Kronenberger, William G.; Henning, Shirley C.; Montgomery, Caitlin J.; Ditmars, Allison M.; Johnson, Courtney A.; Bozell, Hannah D.; Yates, Adeline D.; Pisoni, David B.; Otolaryngology -- Head and Neck Surgery, School of Medicine
    Purpose: Verbal working memory (VWM) delays are commonly found in prelingually deaf youth with cochlear implants (CIs), albeit with considerable interindividual variability. However, little is known about the neurocognitive information-processing mechanisms underlying these delays and how these mechanisms relate to spoken language outcomes. The goal of this study was to use error analysis of the letter-number sequencing (LNS) task to test the hypothesis that VWM delays in CI users are due, in part, to fragile, underspecified phonological representations in short-term memory. Method: Fifty-one CI users aged 7-22 years and 53 normal hearing (NH) peers completed a battery of speech, language, and neurocognitive tests. LNS raw scores and error profiles were compared between samples, and a hierarchical regression model was used to test for associations with measures of speech, language, and hearing. Results: Youth with CIs scored lower on the LNS test than NH peers and committed a significantly higher number of errors involving phonological confusions (recalling an incorrect letter/digit in place of a phonologically similar one). More phonological errors were associated with poorer performance on measures of nonword repetition and following spoken directions but not with hearing quality. Conclusions: Study findings support the hypothesis that poorer VWM in deaf children with CIs is due, in part, to fragile, underspecified phonological representations in short-term/working memory, which underlie spoken language delays. Programs aimed at strengthening phonological representations may improve VWM and spoken language outcomes in CI users.