Inner Ear’s Checkerboard Cell Arrangement Revealed as Key to Hearing

A Japanese research group has made a groundbreaking discovery about the role of the checkerboard-like arrangement of cells in the inner ear’s organ of Corti in hearing. The group, which included Assistant Professor Togashi Hideru of Kobe University’s Graduate School of Medicine and Dr. Katsunuma Sayaka of Hyogo Prefectural Kobe Children’s Hospital, recently published their results in Frontiers in Cell and Developmental Biology.

There are two primary cell types in the organ or Corti — hair cells, which are responsible for hearing, and support cells. The relationship between this checkerboard pattern and hearing function has been a mystery for scientists. The research group discovered that, in mice where the cells in the organ of Corti could not form the checkerboard pattern, only the hair cells died, resulting in deafness. This is the first time it has been understood that the checkerboard layout plays a fundamental structural role in preserving hair cells and their functionality, as the arrangement prevents the hair cells from adhering to each other.

This mosaic pattern of cells has been observed in various sensory organs in many kinds of animals. Understanding the mechanism behind how cell self-organization forms these mosaic patterns will help researchers better understand the functions of a variety of sensory organs and the mechanisms behind disorders.

In this study, the researchers used two types of mice: regular (control) mice and mice with a specific type of cell adhesion molecule, called nectin, not functioning correctly. They measured the hearing of these mice using a test called the auditory brainstem response (ABR) and a test called distortion product otoacoustic emission (DPOAE). They also examined the cells in the mice’s inner ears using immunofluorescence microscopy, a technique involving special dyes and a microscope to visualize specific proteins in the cells.

The team found that the mice with the non-functioning nectin had a disrupted checkerboard pattern in their inner ears and were moderately deaf, suggesting that the checkerboard pattern is essential for hearing. They also observed changes in the cells in the inner ears of these mice, including the death of hair cells and abnormalities in the arrangement of other cells. These findings provide new insights into the mechanisms of hearing and may lead to the development of new treatments for hearing loss disorders.

This discovery gives a new insight into how hearing works from the perspective of cell self-organization and will also enable various hearing loss disorders to be better understood. The research team hopes their findings can help lead to new developments in the treatment of hearing loss disorders.