The main goal of this award is to further my career as a surgeon-scientist by establishing a successful research program. My longstanding interest in treating hearing disorders and, in parallel, performing basic science research on the same topic has fueled my decision to become a pediatric otolaryngologist-scientist. Since my clinical practice focuses on pediatric otology, I am frequently confronted with children suffering from hearing loss. As a physician, I have noticed a major deficiency in our current treatment approach where we cannot reverse sensorineural hearing loss. As a scientist, I hope to establish a research program that will shed light on therapies that restore hearing. To build on my previous research experience, this award is designed to help me develop into an independent investigator through hands-on training and close guidance on experimental designs, techniques, and grant writing. Because Wnt signaling plays major roles in maintaining stem cell populations in other organ systems, we hypothesize that canonical Wnt pathway is involved in the maintenance of cochlear progenitor/stem cells. Likewise, we hypothesize that loss of Wnt signaling or responsiveness is responsible for the inability of the mammalian cochlea to maintain regenerative capacity throughout life. Over the course of a five-year plan, we propose to conduct a series of experiments designed to test two unexplored hypotheses: 1) Wnt responsive cells are endogenous cochlear stem/progenitor cells, and 2) Wnt activation promotes proliferation in cochlear supporting cells. As single cells isolated via flow cytometry, different cochlear cell populations, including Wnt responsive cells and various cochlear supporting cells, are assessed for their ability to self-renew by sphere assays and their ability to generate new hair cells and supporting cells in vitro. Using markers for proliferation and cell lineage analysis in organotypic cultures, we will investigate the effects of Wnt agonists, mitogens, and neomycin-induced hair cell loss on these cells. At the end of this award, we will have evaluated and reported the roles of canonical Wnt signaling in regulating the endogenous Wnt responsive cells and cochlear supporting cells, and whether the Wnt pathway is a promising therapeutic target for hearing restoration. The long-term goal of our research is to maintain or activate a reserve of endogenous stem cells capable of restoring hearing and balance disorders through hair cell/supporting cell regeneration.

Public Health Relevance

Hearing loss affects over 30 million Americans. Current treatment including amplication with hearing aids and cochlear implantation do not reverse one common underlying pathology, loss of hair cells. One potential approach to restore hearing is cell replacement using endogenous stem cells and is the topic of this project.

Agency
National Institute of Health (NIH)
Institute
National Institute on Deafness and Other Communication Disorders (NIDCD)
Type
Clinical Investigator Award (CIA) (K08)
Project #
5K08DC011043-03
Application #
8288858
Study Section
Special Emphasis Panel (ZDC1-SRB-L (49))
Program Officer
Sklare, Dan
Project Start
2010-07-01
Project End
2015-06-30
Budget Start
2012-07-01
Budget End
2013-06-30
Support Year
3
Fiscal Year
2012
Total Cost
$234,500
Indirect Cost
$17,370
Name
Stanford University
Department
Otolaryngology
Type
Schools of Medicine
DUNS #
009214214
City
Stanford
State
CA
Country
United States
Zip Code
94305
Chang, David T; Chai, Renjie; DiMarco, Rebecca et al. (2015) Protein-engineered hydrogel encapsulation for 3-D culture of murine cochlea. Otol Neurotol 36:531-8
Cox, Brandon C; Chai, Renjie; Lenoir, Anne et al. (2014) Spontaneous hair cell regeneration in the neonatal mouse cochlea in vivo. Development 141:816-29
Cox, Brandon C; Chai, Renjie; Lenoir, Anne et al. (2014) Spontaneous hair cell regeneration in the neonatal mouse cochlea in vivo. Development 141:1599
Volkenstein, Stefan; Oshima, Kazuo; Sinkkonen, Saku T et al. (2013) Transient, afferent input-dependent, postnatal niche for neural progenitor cells in the cochlear nucleus. Proc Natl Acad Sci U S A 110:14456-61
Jan, Taha Adnan; Chai, Renjie; Sayyid, Zahra Nabi et al. (2013) Tympanic border cells are Wnt-responsive and can act as progenitors for postnatal mouse cochlear cells. Development 140:1196-206
Vu, Andrew A; Nadaraja, Garani S; Huth, Markus E et al. (2013) Integrity and regeneration of mechanotransduction machinery regulate aminoglycoside entry and sensory cell death. PLoS One 8:e54794
Chai, Renjie; Xia, Anping; Wang, Tian et al. (2011) Dynamic expression of Lgr5, a Wnt target gene, in the developing and mature mouse cochlea. J Assoc Res Otolaryngol 12:455-69
Alharazneh, Abdelrahman; Luk, Lauren; Huth, Markus et al. (2011) Functional hair cell mechanotransducer channels are required for aminoglycoside ototoxicity. PLoS One 6:e22347
Jan, Taha A; Chai, Renjie; Sayyid, Zahra N et al. (2011) Isolating LacZ-expressing cells from mouse inner ear tissues using flow cytometry. J Vis Exp :e3432