Researchers Grow Inner Ear Tissue from Stem Cells

Researchers Grow Inner Ear Tissue from Stem Cells

Since inner ear tissues are not biopsied, researchers find it next to impossible to obtain tissue samples. That hampers studies of disease models and the development of new therapies for balance and hearing disorders.

The ability to grow inner ear tissues in vitro would provide researchers with an invaluable opportunity to develop new treatments for inner ear disorders. However, until now, researchers have only been able to test drugs and therapies on animal cells, which behavior differently to human cells.

Now a team of researchers from the Indiana University School of Medicine have developed a new method for growing inner ear tissue from stem cells.

The researchers used a novel 3D cell culture, which offers numerous advantages over traditional 2D cultures grown in culture dishes. The 3D cultures replicate the environment in the body much more closely allowing more complex cellular interactions to take place.

The researchers grew their 3D cell cultures on floating spherical aggregate and treated the stem cells with signaling molecules to guide development into inner ear ‘organoids.’ Those organoids contained sensory cells along with their supporting cells, similar to inner ear tissues in vivo.

The process took around a year to perfect, but now the team has succeeded in growing multiple inner ear organoids in a pea-sized cell aggregate. The team was able to identify the sensory cells by using CRISPR-Cas9 gene editing to add fluorescent labelling. The sensory cell clusters identified by the researchers had the same functional signatures of inner ear cells and were capable of detecting both motion and gravity.

The inner ear organoids were also discovered to be forming neuronal connections between cells, similar to the neurons that transmit signals from the inner ear to the brain.

Eri Hashino, PhD, Ruth C. Holton Professor of Otolaryngology at IU School of Medicine, said the team’s findings could be “a real game changer,” allowing researchers to test new drugs and therapies on human inner ear cells in vitro.

The team is currently using their inner ear organoids to study how genes known to cause deafness prevent the normal development of the inner ear, with drug screening tests expected to start soon. Hashino said, “We hope to discover new drugs capable of helping regenerate the sound-sending hair cells in the inner ear of those who have severe hearing problems.”

The study was published online in Nature Biotechnology on May 1, 2017.

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