Stanford OHNS Basic and Translational Research Report
Stanford OHNS faculty and trainees are engaged in a wide spectrum of research encompassing including clinical, translational, and basic research. This annual summary encompasses our laboratory research within departmental experimental facilities located in the Edwards, Grant, CCSR, and Lokey buildings on the Stanford medical campus. Our researchers have 64 Extramural grants including 15 NIH R01s and R21s, 2 NIH T32s, U01, P30, DoD, 2 CIRM grants, and many fellowship grants, etc. As we enter 2018, we are #4 in NIH awards to departments in our field and have an annual research budget of over $10 million.
Research at Stanford OHNS became more diverse and more translational in 2017. We welcomed 4 new clinician/scientists (Tulio Valdez , Peter Santa Maria, JP Pepper, Iram Ahmad) working on topics reaching from facial nerve regeneration, otological effects of viral injections in pediatric patients, infrared middle ear diagnostic imaging, and tympanic membrane regeneration. This expansion added diversity particularly with respect to translational clinical work which provides a new basis for our clinician scientists to interact and collaborate with the existing core research programs. We were also joined by a computational biologist (Daibhid O’Maoileidgh) who works on modeling of auditory function.
Our plan for 2018 is to recruit with two additional basic scientists or scientists/clinicians. With our new research building (Biomedical Innovations Building) coming online in early 2020, we have a vision for future growth, particularly of the core research groups focusing on inner ear biology and regenerative medicine, as well as head & neck cancer.
This group consists of Tony Ricci, Alan Cheng, Nicolas Grillet, Daibhid O’Maoileidigh, Peter Santa Maria, and Stefan Heller. Their major accomplishments in 2017 and ongoing research directions are briefly summarized below.
The Alan Cheng laboratory has discovered a surprising link between components of the Wnt signaling pathway and the establishment of the complex architecture of the organ of Corti. This finding, which has not yet been published, was presented at the Association of Research in Otolaryngology annual meeting and has been well received. Towards inner ear regeneration, the Cheng laboratory has identified a single transcription factor capable of regulating the degree of regeneration in the mouse cochlea. This is an important step towards putting together the pieces of the puzzle needed to release the brakes on regeneration in the mammalian cochlea. A third topic of research is focused on revealing the degrees of functional recovery in the utricle, a balance organ responsible for detecting linear acceleration. The Cheng group has identified ways to enhance regeneration and recovery, which is providing a promising lead for new and exciting projects in 2018.
In collaboration with the Tony Ricci laboratory, the Cheng laboratory has continued the development of new non-ototoxic aminoglycoside antibiotics. This work now includes comparative in depth studies that take into account antimicrobial, ototoxic, and biochemical interactions; in this respect, the group has recently obtained first crystal structures of gentamicin derivatives interacting with ribosomes which are providing new insights into drug design to help alleviate ototoxicity from this important class of antibiotics. The main foci of the Ricci group remains in the biophysical investigation of mechano-electrical transduction of hair cells as well as synaptic function. Using the first ever in situ measurements of stereocilia motion, they showed how stereocilia can splay with natural stimulation. They have also investigated the role of the lipid bilayer in mechanotransduction and published two papers on this topic, the key one showing how a specific lipid directly interacts with the mechanotransduction channel to modulate both conductance and sensitivity. Investigation of the role of the ribbon at hair cell afferent fiber synapses was done by characterizing the whole animal and individual synaptic properties in a genetically engineered mouse that does not have ribbon structures. This work will be published by year’s end. A new project is focused on investigating age related hearing loss by characterizing a variety of mouse models known to have hearing loss to determine the timeline of functional loss. The Ricci laboratory has developed an in vivo method of drug delivery and transfection for cochlear hair cells that will be used for in vivo investigation of cellular function but also as the first steps toward gene therapy and direct cochlear drug treatment. This was accompanied by establishing an in vivo imaging system to directly monitor at the cell level, sound stimulation. This new technology has the potential to revolutionize how we investigate cochlear function.
The Nicolas Grillet laboratory uses mouse genetics to investigate inner ear function, and the effects of specific genetic mutations. The LOXHD1 gene is one of these genes causing hearing loss in humans but with variable manifestation of the phenotype: some patients are affected at birth while others are affected from 8 years old in a slowly progressive manner; all this despite the same nature of the genetic mutation. Using mouse models, the Grillet group has discovered that regulation of the gene’s specific expression might contribute to this variability. Furthermore, the Grillet laboratory is on the verge of characterizing the specific function of the Loxhd1 protein in hair cells, which will provide a major boost to the laboratory in 2018. A second project deals with improving scanning electron microscopic imaging of proteins like Loxhd1 combined with simultaneous labeling of the protein with electron-dense particles. This technological advance will be useful to all members of the department and beyond.
New faculty member Daibhid O’Maoileidigh has been rapidly wrapping up his postdoctoral work in form of several major publications that combine theoretical modeling of sensory hair cell processes with experimental validations. This provided time to already focus on a study that compares multiple mechanisms for stochastic resonance. These mechanisms are inherent to the natural process how mechanosensitive hair cells are tuned so that they always operate near their optimal set point for maximizing output in response to stimulation. This study is under review and will be published in the new year. A series of new projects and collaborations has been initiated, which puts the O’Maoileidigh laboratory on an excellent track for 2018.
Likewise, the new Peter Santa Maria laboratory has discovered that a protein named HB-EGF can initiate keratinocyte proliferation and migration in tympanic membrane perforations and chronic suppurative otitis media (CSOM). This novel finding, which was a collaboration with Peter Yang’s laboratory (Orthopedics), who designed a biodegradable polymer for delivery, has been licensed to Astellas Pharmaceuticals. A clinical trial is planned to happen within two years. The Santa Maria group is now focusing on understanding the relationships between Pseudomonas Aeruginosa biofilms in CSOM and EGF receptor signaling of keratinocytes.
Finally, Stefan Heller’s laboratory has been wrapping up an extensive collaboration aimed to determine the order of gene expression during the process of hair bundle development. The hair bundle is the mechanosensitive organelle that provides hair cells with the ability to detect motion caused by sound or vestibular stimuli. This required the development of a novel bioinformatics strategy. A second project, in collaboration with researchers in the Stem Cell Institute, pursues a novel strategy to generate human hair cells from pluripotent stem cells. Along the same lines, the Heller group has concluded and submitted a collaborative project that characterizes the early development of the human inner ear. Finally, a large effort has begun to study at unprecedented detail and depth the mechanisms by which birds regenerate vestibular and auditory hair cells. For this, two surgical model systems were established that allow all planned studies to be conducted in vivo. The parallel development of new methods to analyze temporal and spatial trajectories with single cell transcriptomics will enable the Heller laboratory to unravel the process of hair cell regeneration in non-mammalian vertebrates. In collaboration with the Cheng laboratory, it is planned to combine this knowledge towards development of strategies to initiate regeneration in the mammalian inner ear.
The Tulio Valdez laboratory relocated from Connecticut to Palo Alto in the fall of 2017. Their focus is the development of new otoscopic technology for diagnosis of middle ear disorders, particularly in pediatric patients. This includes the use of label free Raman spectroscopy to determine viscosity characteristics of middle ear fluid. Other research explores the use of already FDA approved dyes to assess inflammation and middle ear status in the clinic. The Valdez group also works on developing and further refining pediatric surgical simulators. These surgical simulators were featured this year in courses in Israel, Argentina, Ecuador and the United States.
Head & Neck Cancer Research
The John Sunwoo laboratory is focused on understanding of how the immune system interfaces with head and neck cancer and on ways to translate this to clinical care of patients. They recently received new funding from the National Cancer Institute and the Parker Institute for Cancer Immunotherapy to support their ongoing work. They, along with their collaborators, have described two methylation subtypes of head and neck cancer that have very different profiles of immune infiltration, and this work was recently published. In addition, the Sunwoo group has continued to make significant progress in understanding basic mechanisms of a special lymphocyte population called natural killer (NK) cells and identified a special memory subset of NK cells. Finally, of particular interest to the Sunwoo laboratory is to understand how the immune system interacts with a tumor-initiating cell population called “cancer stem cells” and how cancer stem cells contribute to metastases. They have described the role of a cell surface receptor called CD271 on the phenotype of these cells and continue with making important contributions to this highly significant field which ultimately aims at new therapies.
The demonstration that antibodies are a valuable approach for surgical imaging in gliomablastoma patients who have contrast enhancing tumors was a major step for the Eben Rosenthal laboratory because this is the first time that antibodies have been demonstrated to penetrate the disrupted blood brain barrier in tumors and therefore be effective in molecular imaging of the brain. Furthermore, microscopy of resected tissues reveals that the antibodies can reach cancer cells as a therapeutic agent. In collaboration with the Department of Neurosurgery (Drs. Li, Grant and Harsh) the Rosenthal group is starting an additional clinical trial to pursue this exciting translational goal.
The Jayakar Nayak laboratory studies both upper airway tissue regeneration and immunology. Upper airway wound repair and regeneration is highly understudied, making it one of a handful of laboratories in the world advancing science in this area. New published findings in 2017 include the identification of molecules, regulatory signals and conditions that promote upper airway tissue differentiation, cell polarity and inflammation. Some of this work led to a prolific collaboration of the Nayak group with three Stem Cell Institute scientists (Drs. Porteus, Kuo and Desai) that was awarded in 2017 the first stem cell grant for an airway disease that the California Institute for Regenerative Medicine has ever bestowed. The overarching goal of the collaborative project is to develop a novel treatment strategy for cystic fibrosis by using CRISPR/Cas9 technology to ‘edit’ and correct the mutated chloride transport gene present in patients. To understand human immunology in chronic rhinosinusitis, the Nayak group uses airway tissues taken directly from patient volunteers undergoing sinus surgery. This year, they reported on the cellular shifts in important T regulatory cell populations in human nasal polyps following steroid use. They also concluded a 3-year collaboration with Northwestern University, and published on the novel discovery of altered levels of immunoglobulin D (IgD) in chronically inflamed airway tissues. Furthermore, the analysis of over 250 chronic rhinosinusitis samples shows that IgD is exclusively found in inflamed upper airway tissues, and not blood or control sinus samples, suggesting a novel pathway of human upper airway immune defense.
Voice disorders are not trivial and have major impacts on human health, health care costs, and economic well-being. Elizabeth DiRenzo’s laboratory studies mucus aggregation, an increased amount of thick, tacky mucus that is commonly observed on the vocal folds in persons with inflammatory voice disorders. Mucus aggregation is one of the most common complaints of persons with voice disorders and leads to phonotraumatic behaviors, negatively impacts vocal fold vibration and voice quality, and may even promote the accumulation of noxious irritants in the larynx. The DiRenzo laboratory focuses on discovering the mechanisms underlying abnormal mucus production in the larynx to identify novel treatment targets. A central hypothesis of the project is that biological mechanisms implicated in mucus overproduction and clinical features of mucus aggregation will be appreciated in the inflammatory, but not normal condition. Elucidation of key biological and clinical properties of the laryngeal mucus layer in nonsmokers (normal condition) and smokers (inflammatory condition) is one approach currently pursued in the laboratory. This research is expected to provide insight into potential mechanisms underlying abnormal mucus aggregation on the vocal folds thereby adding to the knowledge base necessary to develop strategies for normalizing the laryngeal mucus layer in patients.
Nerve Regeneration Research:
Facial paralysis is a debilitating condition that affects thousands of people. Despite excellent surgical technique, the regenerative capacity of the body limits the recovery of patients. The mission of research in the Jon-Paul “JP” Pepper laboratory is to identify new strategies that improve the results of current facial paralysis treatments. They are exploring the regenerative cues that the body uses to restore tissue after nerve injury, in particular through pathways of neurogenesis and nerve repair, such as the hedgehog signaling pathway.
Published December 8, 2017