Nelson, Joel

Hearing and balance disorders affect millions of people worldwide and represent a rapidly growing public health challenge. Hearing loss alone is now recognized as the largest modifiable risk factor for dementia, highlighting its profound impact on long-term cognitive health. Yet despite its importance, damage to the inner ear remains largely irreversible: current treatments such as hearing aids and cochlear implants improve sensory input but do not restore biological function.

The Nelson Lab studies how the inner ear develops at the genetic and molecular levels to understand why some species can regenerate sensory cells, while mammals cannot. During embryonic development, a complex network of signaling pathways, transcription factors, and cell-to-cell interactions guides the formation of the cochlea and vestibular organs. Although decades of research have clarified many of these processes, major gaps remain in translating developmental biology into true regenerative medicine.

Central to hearing and balance are the mechanosensory hair cells, located in the cochlea and in multiple vestibular sensory organs. These cells detect sound and motion with remarkable precision, but once damaged in mammals, through aging, genetic mutations, noise exposure, or medications (such as certain antibiotics and chemotherapies), they do not regenerate. In contrast, non-mammalian vertebrates like fish and birds are capable of regenerating hair cells and restoring function, offering powerful clues for future therapeutic strategies.

Our research integrates genetics, molecular biology, developmental biology, and bioinformatics to uncover the molecular programs that build the inner ear and compare how these programs differ across species. We work with datasets derived from embryonic mouse models, providing a detailed framework for identifying key genes and pathways active during inner ear formation. In parallel, we use zebrafish as a regenerative model to contextualize these findings and reveal evolutionary principles that may point toward mechanisms of repair in mammals. We use a range of experimental approaches including immunohistochemistry (IHC) to visualize protein expression, fluorescent in situ hybridization (FISH) to map gene expression patterns, and

small-molecule inhibition to test the functional roles of signaling pathways.

By mapping the genetic and molecular signals that drive inner ear development, and understanding why regeneration succeeds in some species but not others, the Nelson Lab aims to generate foundational insights that can ultimately inform strategies to restore hearing and balance in humans.