Swedish researchers have discovered how the inner ear is formed in mice by labelling stem cells with a genetic ‘barcode’ and following the cells’ developmental journey.
They discovered that cells in the inner ear, which are crucial for hearing, develop from two main types of stem cells. They hope this discovery can lead to new treatments for hearing loss.
Writing in Science on 3 April 2025, the researchers said they developed a method that shows how the nervous system and sensory organs are formed in an embryo.
“Our study shows how different cell types arise from stem cells in the embryo and how they are organised to create important structures in the brain,” said Associate Professor Emma Andersson from the Department of Cell and Molecular Biology, Karolinska Institutet, Sweden.
“You could say that we have created a family tree for the cells of the nervous system and the inner ear.”
They injected a virus into mouse stem cells at an early stage of development. The virus contained a genetic ‘barcode’ that was integrated into the DNA of the stem cells and then inherited as the cells divided.
By following this code, the researchers could track how the cells developed into different types of neurons and cells in the inner ear.
“Tracing the origin and development of cells gives us a unique opportunity to understand the basic mechanisms behind hearing loss,” A/Prof Andersson said. “It can help us find new ways to repair or replace damaged cells in the inner ear.”
She led the study with Ms Jingyan He, a postdoctoral fellow, and Ms Sandra de Haan, a former PhD student in A/Prof Andersson’s research group.
Mr Mattia Maroso, the editor of Science, said they determined the various cell types in the cochlear epithelium, neural crest-derived glia, and intermediate cells in the cochlear.
“Their results led to the identification of cell types that were previously misclassified and represent a comprehensive single-cell atlas of clonal relationships within the mouse cochlea,” he wrote.
The team plans to use the method to study other parts of the nervous system and how the rest of the body develops. It hopes the work will lead to new insights and treatments for various genetic and developmental diseases.
“We are only at the beginning of understanding the complex processes behind nervous system development,” A/Prof Andersson said.
“Our method opens up many exciting opportunities to explore how the nervous system and the rest of the body are formed during embryonic development. In addition, the technique can reduce the number of mice used in research.”
