Japanese researchers have succeeded in producing specialised cells that could help bring about a therapeutic cure for the most common form of congenital deafness.
One in a thousand children suffers deafness or hearing loss, and hearing is the most common sense to be affected by congenital disease. Deafness at birth is often caused by mutations in a specific gene known as Gap Junction Beta 2 (GJB2), which codes for the protein connexin 26. In some populations mutations of this gene are responsible for as many as half the instances of congenital hearing loss.
Stem cells – which occur in embryos as embryonic stem cells (ESCs) and in adults as repair cells – can change into more specialised cells through a process described as ‘differentiation’. ESCs can differentiate into a several different types of specialised cells to form the range of cells needed in the human body. This ability to differentiate is described as ‘pluripotency’ and can be induced in adult cells as well by reprogramming non-reproductive system cells (somatic cells) to produce ‘induced pluripotent stem cells’ (iPSCs).
Human cochlear cells are not readily accessible for biopsy or direct drug administration because of anatomical limitations. Therefore, ES/iPS [embryo stem/induced pluripotent stem]cells are an important tool for studying the molecular mechanisms underlying inner-ear pathology as well as for generating cells for replacement therapies.
The article in Stem Cell Reports says.
As well as inducing the specialised cells the researchers were able to demonstrate that they were functionally and structurally characteristic of developing cochlear cells.
Their report concludes:
‘It is expected, then, that these iPS derived cells, which can be obtained from patients, will be particularly useful for drug screening and inner-ear cell therapies targeting GJB2-related hearing loss.’
The hope is that the latest breakthrough will lead to a therapeutic treatment for GJB2-related hearing loss in five to 10 years.