A simple protocol for generating inner ear hair cells to restore hearing has been developed by researchers from the Molecular Medicine Institute in Lisbon, Portugal, and the University College London Ear Institute in the United Kingdom. According to an article published in the June 1, 2015 edition of the journal Development, the research study brings scientists a step closer to generating these sensory hair cells in large numbers for use in drug screening and cell transplantation.

Domingos Henrique, PhD

Domingos Henrique, PhD

Previous research has shown that sensory hair cells located in the inner ear are vital for hearing and balance and that, when damaged, they lead to hearing and balance impairments. While other studies have reported the successful regeneration of hair cells in the lab, the protocols used were complex and inefficient. The study conducted by the research teams in Lisbon and London was aimed at overcoming these problems by following a different strategy.

“We explored the extensive knowledge on the various regulatory proteins that control hair cell development in the embryo to design an effective combination of three transcription factors able to induce the formation of these cells,” said Domingos Henrique, PhD, the lead investigator on the team at the Molecular Medicine Institute.

Henrique reported in a recent announcement that the team applied a simpler approach to manipulating mouse embryonic stem cells in a dish, which have the potential to become any cell type. By introducing the three transcription factors, they were able to convert these cells into hair cells with comparatively greater efficiency than previously reported by other researchers. The team applied the same protocol to cells in the ear of a developing chick embryo where they were also able to induce the formation of many new hair cells, including in areas where hair cells do not normally form, which indicates that a similar strategy might work in vivo.

“Hair cells get their name from the bundle of hair-like structures that protrude from the cell,” reported Henrique and his co-authors. “These protrusions have mechanosensitive ion channels that allow hair cells to transform vibrational movements into electrical signals. We observed that the hair cells we produced are also able to develop similar protrusions, but with an immature and disorganized morphology. However, we have some evidence suggesting that functional mechanosensitive ion channels are already present in these cells, and that the genes expressed by normal hair cells and those produced by us in a dish are very similar.”

According to the authors, future work will focus both on improving this protocol to produce fully mature hair cells, and on applying the method to human cells that can be produced in large quantities for potential drug screening and cell replacement therapies.

Source: Development, Molecular Medicine Institute, University College London Ear Institute, DHenrique Laboratory

Photo credits: Molecular Medicine Institute; © Anyaivanova | Dreamstime.com