By Marie Kubota, Ph.D.
Permanent hearing loss is often the result of loss of mechanosensitive sensory hair cells inside the cochlea. Hair cells are susceptible to noise damage, infection, ototoxic agents, and the effects of aging. Although cochlear hair cell regeneration does not occur in adult mammals, including humans, studies have shown that, in the neonatal mouse, nonsensory cochlear cells have a limited and transient ability to generate new hair cells. For example, isolated cochlear cells of newborn mice can grow into spherical balls of cells, so-called organoids. These organoids grow and can be differentiated cells that resemble young hair cells and their surrounding supporting cells.
A surprising finding of this project was that a specific group of cells, called the greater epithelial ridge (GER), contained the majority of cells capable of growing into organoids. This ability can be interpreted as a form of regenerative potential because the GER cells can multiply and generate new sensory hair cells. (FACS is a cell sorting technology.)
Our team used specific cell culture conditions for the efficient generation of inner ear organoids. We then used a cell sorting technology called FACS to purify the different cochlear cell subtypes, and then compared the individual organoid-formation capacity of each cell group.
A surprising finding of this project was that a specific group of cells, called the greater epithelial ridge (GER), contained the majority of cells capable of growing into organoids. This ability can be interpreted as a form of regenerative potential because the GER cells can multiply and generate new sensory hair cells.
GER cells occur only in the cochlea of newborn mice, and they are no longer present in adult mice. Our findings provide methods to purify these cells, inspiring future studies to research why GER cells have regenerative capacity. The principal discovery was published in January 2021 in the journal Cell Reports. The methods for GER cell purification were published in STAR Protocols in September 2021.
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