Scientists show you the inner ear cell development

Scientists now have created the first high-resolution gene expression map of the newborn mouse inner ear by use of a a sensitive new technology called single-cell RNA-seq on cells from mice. It helps scientists to know more about how epithelial cells in the inner ear develop and differentiate into specialized cells that serve critical functions for hearing and maintaining balance. The potential development of cell-based therapies for treating hearing loss and balance disorders will be pushed by the findings. It were scientists from the National Institute on Deafness and Other Communication Disorders (NIDCD), part of the National Institutes of Health that conduted the research.
In another study, also published in the journal Nature Communications on October 15, researchers used a similar technique to identify a family of proteins which are important for the development of inner ear cells.
"Age-related hearing loss occurs gradually in most of us as we grow older. It is one of the most common conditions among older adults, affecting half of people over age 75. These new findings may lead to new regenerative treatments for this critical public health issue." said James F. Battey, Jr., M.D., Ph.D., director of the NIDCD.
Sensory epithelial cells in the inner ear include hair cells and supporting cells. The latter one provides the former one with crucial structural and functional support. Both kinds of them located in the cochlea--the snail-shaped structure in the inner ear. They work together to detect sound, so we can hear. On the contrary, hair cells and supporting cells in the utricle, which is a fluid-filled pouch near the cochlea, is critical to maintain our balance. They detect how we move our heads and how our heads are positioned. This information tells our brain whether we are standing or lying down or some other condition. The utricle, with other structures and organs in the body that provide our sense of balance, comprise the vestibular system together.
Medications, infections or disease, injury, or aging can damage hair cells and supporting cells, which results in hearing loss and balance problems. For humans, the cells cannot naturally repair themselves, thus effective treatments are limited.
What's worse, there are only a few thousand of these sensory cells , and they are deep in a bony channel, which makes them hard to study.
To know more about the inner ear cell development, a new technology was used by Matthew Kelley, Ph.D., chief of the Section on Developmental Neuroscience at the NIDCD, and his research team to do a related research. The technology is single-cell RNA-seq, which can extract comprehensive gene activity data from just one cell, while other methods need thousands of cells. Scientists can learn a lot about a cell's individual characteristics and function from knowing which genes are active.
They analyzed 301 cells taken from the cochlea and utricle of newborn mice and found unique patterns in hair cells and supporting cells. Evidence for subgroups of cells within each of these classes was also uncovered. The researchers speculate that the cells' distinct gene activity patterns may reflect specialized functions. The finding also helped the scientists to identify distinct developmental patterns of gene activity. Cells in the vestibular part of the inner ear develop at somewhat different rates, so each cell was at a slightly different point in its maturity when the researchers examined it. By analyzing the cells' gene activity profiles, the scientists were able to identify genes that are active at each stage of development, helping to understand about how the specialized hair cells are formed.
"Using this single-cell profiling technique provides a new option to identify the genetic activity of cells, particularly in systems with limited numbers of cells, like the inner ear," said Kelley, senior author of the study. "Identifying the gene expression maps for the development of inner ear cells is essential to understanding how they form, and may help us create ways to regenerate these cells."
Through the study, the scientists also found that a group of gene regulators called Regulatory Factor Xs (RFX) helps to drive genes that are preferentially active in hair cells. They also showed that RFX genes have an essential role in hearing.
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