In view of the prevalence of sensorineural hearing defects in an ageing population, the development of protocols to generate cochlear hair cells and their associated sensory neurons as tools to ...further our understanding of inner ear development are highly desirable. We report herein a robust protocol for the generation of both vestibular and cochlear hair cells from human pluripotent stem cells which represents an advance over currently available methods that have been reported to generate vestibular hair cells only. Generating otic organoids from human pluripotent stem cells using a three-dimensional culture system, we show formation of both types of sensory hair cells bearing stereociliary bundles with active mechano-sensory ion channels. These cells share many morphological characteristics with their in vivo counterparts during embryonic development of the cochlear and vestibular organs and moreover demonstrate electrophysiological activity detected through single-cell patch clamping. Collectively these data represent an advance in our ability to generate cells of an otic lineage and will be useful for building models of the sensory regions of the cochlea and vestibule.
COVID-19 is a pandemic respiratory and vascular disease caused by SARS-CoV-2 virus. There is a growing number of sensory deficits associated with COVID-19 and molecular mechanisms underlying these ...deficits are incompletely understood.
We report a series of ten COVID-19 patients with audiovestibular symptoms such as hearing loss, vestibular dysfunction and tinnitus. To investigate the causal relationship between SARS-CoV-2 and audiovestibular dysfunction, we examine human inner ear tissue, human inner ear in vitro cellular models, and mouse inner ear tissue.
We demonstrate that adult human inner ear tissue co-expresses the angiotensin-converting enzyme 2 (ACE2) receptor for SARS-CoV-2 virus, and the transmembrane protease serine 2 (TMPRSS2) and FURIN cofactors required for virus entry. Furthermore, hair cells and Schwann cells in explanted human vestibular tissue can be infected by SARS-CoV-2, as demonstrated by confocal microscopy. We establish three human induced pluripotent stem cell (hiPSC)-derived in vitro models of the inner ear for infection: two-dimensional otic prosensory cells (OPCs) and Schwann cell precursors (SCPs), and three-dimensional inner ear organoids. Both OPCs and SCPs express ACE2, TMPRSS2, and FURIN, with lower ACE2 and FURIN expression in SCPs. OPCs are permissive to SARS-CoV-2 infection; lower infection rates exist in isogenic SCPs. The inner ear organoids show that hair cells express ACE2 and are targets for SARS-CoV-2.
Our results provide mechanistic explanations of audiovestibular dysfunction in COVID-19 patients and introduce hiPSC-derived systems for studying infectious human otologic disease.
Congenital hearing loss is a common chronic condition affecting children in both developed and developing nations. Viruses correlated with congenital hearing loss include human cytomegalovirus (HCMV) ...and Zika virus (ZIKV), which causes congenital Zika syndrome. The mechanisms by which HCMV and ZIKV infections cause hearing loss are poorly understood. It is challenging to study human inner ear cells because they are encased in bone and also scarce as autopsy samples. Recent advances in culturing human stem cell-derived otic progenitor cells (OPCs) have allowed us herein to describe successful
infection of OPCs with HCMV and ZIKV, and also to propose potential mechanisms by which each viral infection could affect hearing. We find that ZIKV infection rapidly and significantly induces the expression of type I interferon and interferon-stimulated genes, while OPC viability declines, at least in part, from apoptosis. In contrast, HCMV infection did not appear to upregulate interferons or cause a reduction in cell viability, and instead disrupted expression of key genes and pathways associated with inner ear development and function, including Cochlin, nerve growth factor receptor, SRY-box transcription factor 11, and transforming growth factor-beta signaling. These findings suggest that ZIKV and HCMV infections cause congenital hearing loss through distinct pathways, that is, by inducing progenitor cell death in the case of ZIKV infection, and by disruption of critical developmental pathways in the case of HCMV infection.
Congenital virus infections inflict substantial morbidity and devastating disease in neonates worldwide, and hearing loss is a common outcome. It has been difficult to study viral infections of the human hearing apparatus because it is embedded in the temporal bone of the skull. Recent technological advances permit the differentiation of otic progenitor cells (OPCs) from human-induced pluripotent stem cells. This paper is important for demonstrating that inner ear virus infections can be modeled
using OPCs. We infected OPCs with two viruses associated with congenital hearing loss: human cytomegalovirus (HCMV), a DNA virus, or Zika virus (ZIKV), an RNA virus. An important result is that the gene expression and cytokine production profiles of HCMV/ZIKV-infected OPCs are markedly dissimilar, suggesting that mechanisms of hearing loss are also distinct. The specific molecular regulatory pathways identified in this work could suggest important targets for therapeutics.
The fibroblast growth factor 2 (FGF2) is a member of the FGF family which is involved in key biological processes including development, cellular proliferation, wound healing, and angiogenesis. ...Although the utility of the FGF family as therapeutic agents has attracted attention, and FGF2 has been studied in several clinical contexts, there remains an incomplete understanding of the molecular and clinical function of FGF2 in the auditory system. In this review, we highlight the role of FGF2 in inner ear development and hearing protection and present relevant clinical studies for tympanic membrane (TM) repair. We conclude by discussing the future implications of FGF2 as a potential therapeutic agent.
Hearing loss (HL) is a major global health problem of pandemic proportions. The most common type of HL is sensorineural hearing loss (SNHL) which typically occurs when cells within the inner ear are ...damaged. Human induced pluripotent stem cells (hiPSCs) can be generated from any individual including those who suffer from different types of HL. The development of new differentiation protocols to obtain cells of the inner ear including hair cells (HCs) and spiral ganglion neurons (SGNs) promises to expedite cell‐based therapy and screening of potential pharmacologic and genetic therapies using human models. Considering age‐related, acoustic, ototoxic, and genetic insults which are the most frequent causes of irreversible damage of HCs and SGNs, new methods of genome editing (GE), especially the CRISPR/Cas9 technology, could bring additional opportunities to understand the pathogenesis of human SNHL and identify novel therapies. However, important challenges associated with both hiPSCs and GE need to be overcome before scientific discoveries are correctly translated to effective and patient‐safe applications. The purpose of the present review is (a) to summarize the findings from published reports utilizing hiPSCs for studies of SNHL, hence complementing recent reviews focused on animal studies, and (b) to outline promising future directions for deciphering SNHL using disruptive molecular and genomic technologies.
Fibroblasts or blood from healthy donors and patients with sensorineural hearing loss (SNHL) are used to derive human induced pluripotent stem cells (hiPSCs) which can be subjected to genome editing, then differentiated into two dimensional (2D) and three dimensional (3D) inner ear cellular models for multiple downstream applications, including functional, mechanistic, therapeutic and drug screening studies
Previously isolated rat extraembryonic endoderm precursor (XENP) cell lines had been characterized after clonal density plating. The arising colonies had consisted of peripheral XENP cells expressing ...the surface antigen SSEA1 and the transcription factor Oct4, and inner XENP-derived extraembryonic endoderm cells that were nearly negative for SSEA1 and Oct4. We now sorted bulk-cultured XENP cell lines from two rat strains by FACS into SSEA1
+
and SSEA1
−
populations and compared their expression profiles by microarray and RT-PCR. In the bulk cultures, the SSEA1
+
fraction was only slightly enriched for Oct4, and also slightly enriched for the visceral endoderm markers, Dab2 and Ihh. Both fractions expressed vascular-associated mesodermal markers (VE-cadherin, Flk1). Thus, in regular-density XENP cell cultures, SSEA1 is not suitable as a stem cell marker, and the XENP cells appear to undergo partial somatic differentiation.
Hearing loss is among the most common of sensory impairments and there are over 500 million deaf individuals in the world. Currently, most treatment strategies depend on acoustic amplification or ...cochlear implantation in severe cases. These electronic devices can give help to those with hearing loss, but they are not perfect cures for deafness. Over the last decade, stem cell technology has received a great attention as a possible and powerful treatment for a number of diseases. The induction of human inner ear tissue from pluripotent stem cells would be applicable not only to modelling of sensorineural hearing loss disease but also for the generation of clinically useful sensory cells. In this study, we have developed a method for differentiating human pluripotent stem cells to inner ear cells. Using a three-dimensional culture system, we modulated TGF, BMP, and FGF signalling to generate otic vesicle-like structures alongside neural progenitor cells from stem cell embryoid bodies (EBs). Over 3 months, the vesicles developed into EBs that give rise to sensory hair cells bearing stereocilia bundles that are innervated by possible sensory neurons. Additionally, using FM1-43FX we detected hair-cell-like cells and possible sensory neurons that have active mechanotransduction ion channels. We also showed that derived neurons exhibit electrophysiological properties similar to primary auditory neurons of the rat cochlea. Finally, we demonstrated how these otic EBs are structurally and biochemically similar to developing human cochlear and vestibular organs. We believe that this study would facilitate the study of human inner ear development and also could benefit a broad range of individuals suffering from sensorineural hearing loss.
Dark matter could decay into Standard Model particles producing neutrinos directly or indirectly. The resulting flux of neutrinos from these decays could be detectable at neutrino telescopes and ...would be associated with massive celestial objects where dark matter is expected to be accumulated. Recent observations of high-energy astrophysical neutrinos at IceCube might hint at a signal produced by the decay of TeV to PeV scale dark matter. This analysis searches for neutrinos from decaying dark matter in nearby galaxy clusters and galaxies. We focus on dark matter masses from 10 TeV to 1 EeV and four decay channels: \(\nu\bar{\nu}\), \(\tau^{+}\tau^{-}\), \(W^{+}W^{-}\), \(b\bar{b}\). Three galaxy clusters, seven dwarf galaxies, and the Andromeda galaxy are chosen as targets and stacked within the same source class. A well-established IceCube data sample is used, which contains 11 years of upward-going track-like events. In this contribution, we present preliminary results of the analysis.
The SPICEcore Hole Camera System Dujmović, Hrvoje; Jeong, Minjin; Tönnis, Christoph ...
arXiv (Cornell University),
08/2019
Paper, Journal Article
Open access
IceCube is a cubic-kilometer scale neutrino telescope located at the geographic South Pole. The detector utilizes the extremely transparent Antarctic ice as a medium for detecting Cherenkov radiation ...from neutrino interactions. As a result of extensive studies of the optical properties of ice, the light propagation in IceCube is well understood. The ice properties are, however, still dominant sources of detector systematic uncertainties in many IceCube analyses. We have designed a camera system to measure the optical properties of the Antarctic ice surrounding the SPICEcore hole that is an ice-core hole drilled down to 1.7~km near the IceCube detector. The device uses CMOS image sensors to measure the back-scattered light from bright LEDs pointing into the ice. Having a similar measurement principle, the device can also serve as a proof of concept of a camera system designed for the optical modules for IceCube Upgrade. During the 2018/2019 austral summer season, a prototype of the instrument was deployed in the ice-core hole. In this contribution, we present the hardware design of the camera system and the result of the first deployment at the South Pole.
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