Xiaolei Yin

The cells in our ears that enable us to hear are delicate, easily destroyed by exposure to loud sounds and some medications. The body is unable to regenerate them, so when these cells die, our hearing is permanently damaged.

BWH researchers recently developed a new technique for growing large amounts of these specialized cells in a lab, pioneering the way toward a possible treatment for hearing loss.

Inner ear sensory cells, also known as hair cells, are responsible for detecting sound and helping to signal it to the brain. They can be produced artificially, but scientists have struggled historically to produce them in quantities large enough to recover a person’s hearing. Humans are born with 15,000 sensory hair cells in each cochlea, a region of the inner ear.

To figure out how to grow these cells en masse, researchers looked to the animal kingdom for answers.

“Amazingly, birds and amphibians are capable of regenerating hair cells throughout their life, suggesting that the biology exists and should be possible for humans. Intrigued, we decided to explore whether these hair cells could be regenerated,” said Jeff Karp, PhD, biomedical engineer at BWH and co-corresponding author of a recent paper in Cell Reports about the findings.

Jeff Karp

In their paper, scientists from the Brigham, Massachusetts Institute of Technology and Massachusetts Eye & Ear describe a technique to grow large quantities of inner ear progenitor cells, which can be programmed to turn into specific types of cells. In this case, researchers converted them into hair cells. The same techniques show the ability to regenerate hair cells in the cochlea.

To accomplish this, researchers took cells expressing a particular biomarker, known as Lgr5, and treated them with a drug cocktail that stimulated critical pathways, says Xiaolei Yin, PhD, co-lead author on the paper, of the Department of Medicine.

This technique produced more than 2,000 times the number of progenitor cells than what had been achieved in prior studies. The next step was to turn them into hair cells. Large quantities of those progenitor cells were successfully converted, resulting in approximately 60 times more hair cells from a single isolated cochlea than previously reported. The team also demonstrated this approach could work with cells from preclinical models and human tissue.

The drug cocktail “generates new sensory hair cells in intact cochlear tissue, which shows promise for a therapy to treat patients with hearing loss,” Karp said.

Frequency Therapeutics, a bioengineering company based in Woburn, is advancing this work from the lab to patient care settings. The company, for which Karp and Yin are scientific advisory board members, is using these new techniques to develop a therapy to treat chronic hearing loss. The treatment is expected to be in clinical settings within the next 18 months.