Listen Here: Stem Cells Open the Door For Hearing Loss Treatments

The Context: Approximately 48 million Americans have some degree of hearing loss, largely due to damage of hair cells in the ears that make hearing possible. There are currently no strategies for repairing hair cells.

The Study: NYSCF – Robertson Stem Cell Investigator Justin Ichida, PhD, of the University of Southern California has established a method for generating ‘induced hair cell-like cells’, or ‘iHCs,’ from mouse stem cells. The study appears in eLife. 

The Importance: These iHCs are giving researchers a tool for studying hearing loss, testing drugs, and developing new therapies to repair the hair cells in our ears.

The cells that make hearing possible are called ‘hair cells’ because of their hair-like appearance under a microscope, and the ~15,000 of these cells that live in your ears are precious. They’re easily damaged and currently unrepairable. 

A new study in eLife from researchers at the University of Southern California led by NYSCF – Robertson Stem Cell Investigator Justin Ichida, PhD, has established a method for creating hair cells from mouse stem cells, opening the door for further study of hearing loss and development of new therapies.

“Aging, loud noises, and certain chemotherapy drugs and antibiotics can all lead to the permanent loss of hair cells, which is the leading contributor to hearing loss worldwide,” remarked Neil Segil, PhD, a professor in the Department of Stem Cell Biology and Regenerative Medicine, and the USC Tina and Rick Caruso Department of Otolaryngology – Head and Neck Surgery, and one of the corresponding authors of the study. 

The team established methods for creating hair-like cells from three different types of mouse cells: inner ear support cells, young connective tissue cells called fibroblasts, and mature fibroblasts.

“We’ve succeeded in directly reprogramming a variety of mouse cell types into what we’re calling ‘induced hair cell-like cells, or iHCs,” added PhD student Louise Menendez, the study’s lead author, in an article from USC. “This allows us to efficiently generate large numbers of iHCs to identify causes and treatments for hearing loss.”

Excitingly, the iHCs resemble typical hair cells in their structure and behavior, and understanding how to turn inner ear support cells and fibroblasts into iHCs opens up the possibility for a gene therapy that can directly restore hair cells in patients with hearing loss.

“In the near term, researchers can use iHCs to screen large numbers of drug candidates that might prevent or treat hearing loss,” said Dr. Ichida, the John Douglas French Alzheimer’s Foundation Associate Professor of Stem Cell Biology and Regenerative Medicine at USC. “And further in the future, it could become possible to directly reprogram supporting cells in the inner ear of a deafened individual, as a way to restore hearing.”

Journal Article:

Generation of inner ear hair cells by direct lineage conversion of primary somatic cells
Louise Menendez, Talon Trecek, Suhasni Gopalakrishnan, Litao Tao, Alexander L Markowitz, Haoze V Yu, Xizi Wang, Juan Llamas, Chichou Huang, James Lee, Radha Kalluri, Justin Ichida, Neil Segil. 2020. eLife. DOI: 10.7554/eLife.55249

Photo by Damon Casarez, USC