Departmental Senator, Medical School Faculty Senate (2008 - 2011) Director of Research, Otolaryngology - Stanford (2005 - 2014) Provost's Advisory Committee on Postdoctoral Affairs, Stanford (2009 - 2017) Vice Chair for Research, Otolaryngology - Stanford (2014 - 2019)


  • Greater epithelial ridge cells are the principal organoid-forming progenitors of the mouse cochlea. Cell reports Kubota, M. n., Scheibinger, M. n., Jan, T. A., Heller, S. n. 2021; 34 (3): 108646


    In mammals, hearing loss is irreversible due to the lack of regenerative potential of non-sensory cochlear cells. Neonatal cochlear cells, however, can grow into organoids that harbor sensory epithelial cells, including hair cells and supporting cells. Here, we purify different cochlear cell types from neonatal mice, validate the composition of the different groups with single-cell RNA sequencing (RNA-seq), and assess the various groups' potential to grow into inner ear organoids. We find that the greater epithelial ridge (GER), a transient cell population that disappears during post-natal cochlear maturation, harbors the most potent organoid-forming cells. We identified three distinct GER cell groups that correlate with a specific spatial distribution of marker genes. Organoid formation was synergistically enhanced when the cells were cultured at increasing density. This effect is not due to diffusible signals but requires direct cell-to-cell contact. Our findings improve the development of cell-based assays to study culture-generated inner ear cell types.

    View details for DOI 10.1016/j.celrep.2020.108646

    View details for PubMedID 33472062

  • Transcriptomic characterization of dying hair cells in the avian cochlea. Cell reports Benkafadar, N. n., Janesick, A. n., Scheibinger, M. n., Ling, A. H., Jan, T. A., Heller, S. n. 2021; 34 (12): 108902


    Sensory hair cells are prone to apoptosis caused by various drugs including aminoglycoside antibiotics. In mammals, this vulnerability results in permanent hearing loss because lost hair cells are not regenerated. Conversely, hair cells regenerate in birds, making the avian inner ear an exquisite model for studying ototoxicity and regeneration. Here, we use single-cell RNA sequencing and trajectory analysis on control and dying hair cells after aminoglycoside treatment. Interestingly, the two major subtypes of avian cochlear hair cells, tall and short hair cells, respond differently. Dying short hair cells show a noticeable transient upregulation of many more genes than tall hair cells. The most prominent gene group identified is associated with potassium ion conductances, suggesting distinct physiological differences. Moreover, the dynamic characterization of >15,000 genes expressed in tall and short avian hair cells during their apoptotic demise comprises a resource for further investigations toward mammalian hair cell protection and hair cell regeneration.

    View details for DOI 10.1016/j.celrep.2021.108902

    View details for PubMedID 33761357

  • Cell-type identity of the avian cochlea. Cell reports Janesick, A. n., Scheibinger, M. n., Benkafadar, N. n., Kirti, S. n., Ellwanger, D. C., Heller, S. n. 2021; 34 (12): 108900


    In contrast to mammals, birds recover naturally from acquired hearing loss, which makes them an ideal model for inner ear regeneration research. Here, we present a validated single-cell RNA sequencing resource of the avian cochlea. We describe specific markers for three distinct types of sensory hair cells, including a previously unknown subgroup, which we call superior tall hair cells. We identify markers for the supporting cells associated with tall hair cells, which represent the facultative stem cells of the avian inner ear. Likewise, we present markers for supporting cells that are located below the short cochlear hair cells. We further infer spatial expression gradients of hair cell genes along the tonotopic axis of the cochlea. This resource advances neurobiology, comparative biology, and regenerative medicine by providing a basis for comparative studies with non-regenerating mammalian cochleae and for longitudinal studies of the regenerating avian cochlea.

    View details for DOI 10.1016/j.celrep.2021.108900

    View details for PubMedID 33761346

  • Stem Cell Approaches and Small Molecules The Senses: A Comprehensive Reference Romano, D. R., Heller, S., Hashino , E. Elsevier . 2020; 2: 945–962
  • Hair-bearing human skin generated entirely from pluripotent stem cells. Nature Lee, J. n., Rabbani, C. C., Gao, H. n., Steinhart, M. R., Woodruff, B. M., Pflum, Z. E., Kim, A. n., Heller, S. n., Liu, Y. n., Shipchandler, T. Z., Koehler, K. R. 2020


    The skin is a multilayered organ, equipped with appendages (that is, follicles and glands), that is critical for regulating body temperature and the retention of bodily fluids, guarding against external stresses and mediating the sensation of touch and pain1,2. Reconstructing appendage-bearing skin in cultures and in bioengineered grafts is a biomedical challenge that has yet to be met3-9. Here we report an organoid culture system that generates complex skin from human pluripotent stem cells. We use stepwise modulation of the transforming growth factor β (TGFβ) and fibroblast growth factor (FGF) signalling pathways to co-induce cranial epithelial cells and neural crest cells within a spherical cell aggregate. During an incubation period of 4-5 months, we observe the emergence of a cyst-like skin organoid composed of stratified epidermis, fat-rich dermis and pigmented hair follicles that are equipped with sebaceous glands. A network of sensory neurons and Schwann cells form nerve-like bundles that target Merkel cells in organoid hair follicles, mimicking the neural circuitry associated with human touch. Single-cell RNA sequencing and direct comparison to fetal specimens suggest that the skin organoids are equivalent to the facial skin of human fetuses in the second trimester of development. Moreover, we show that skin organoids form planar hair-bearing skin when grafted onto nude mice. Together, our results demonstrate that nearly complete skin can self-assemble in vitro and be used to reconstitute skin in vivo. We anticipate that our skin organoids will provide a foundation for future studies of human skin development, disease modelling and reconstructive surgery.

    View details for DOI 10.1038/s41586-020-2352-3

    View details for PubMedID 32494013

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