Researchers from Nanjing University in China recently published new research in Stem Cell Reports about lab-grown cochlear organoids that enable screening for potential drugs that promote hair cell regeneration, which is impossible in mammals.
Phys.org reported that the team believes that lost hair cells could be repaired or replaced given the right conditions, like other animals like fish and birds who can regenerate their lost hair cells.
Cochlear Hair Cells Aid Perception of Sound
Hearing is a complex process that involves three key parts of the ear, according to the National Institute of Deafness and Other Communication Disorders. Sounds are collected by the pinna of the outer ear and then funneled into the ear canal before reaching the middle ear.
According to Technology Networks, it will cause vibrations in the eardrum that will be transmitted to the ossicles made up of small bones. Then the movement of the bones in the inner ear will signal the fluid in the cochlea to stimulate the hair cells, which are tuned to respond to sound pitches. Those located at the cochlea's widest part detect higher pitches, whereas those at the center.
Technically, the cochlear hair cells are responsible for generating an electrical signal detected by the auditory nerve and sends it to the brain, which registers it to a sound that people recognize.
However, loss of hair cells through exposure to loud sounds, aging, chemicals, diseases cannot be replaced or repaired, which results in partial or complete hearing loss. While birds and fishes can regenerate hair cells, mammals like humans cannot.
Cochlear Organoids Enable Screening of Hair-Cell Inducing Drugs
In the study, titled "High-Throughput Screening on Cochlear Organoids Identifies VEGFR-MEK-TGFB1 Signaling Promoting Hair Cell Reprogramming," Guoqiang Wan and colleagues from Nanjing University generated cultures of immature neonatal mouse cochlear organoids.
As Phys.org reported, hair cells started multiplying and growing in these cochlear organoids over time while in the laboratory. These cochlear organoids were used to screen over one thousand Food and Drugs Administration-approved hair cell-inducing drugs.
One of them is the Regorafenib, which is an anti-cancer drug but promotes hair cell formation in the cochlear organoids. Additionally, this drug also induced hair fall formation in mouse cochlear tissues even after being destroyed by exposure to harmful chemicals.
Researchers noted that their research sets the stage for high throughput for screening possible approaches in identifying drugs that promote hair cell regeneration in mammals that could be used as a potential treatment for hearing loss.
On the other hand, the team emphasized that further study is needed to test its safety and determine whether the identified hair cell-inducing drugs could promote hair cell regeneration in human cochleas as it did in the lab-grown mouse cochlear organoids.
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