After a decade of research scientists have discovered the recipe for hearing - a way to coax embryonic stem cells as well as reprogrammed adult cells to develop into sensory cells that normally reside in the mammalian inner ear.
Those mechanosensitive sensory hair cells are the linchpin of hearing and balance.
Assuming their recipe can be further perfected to reliably generate hair cells in the millions, it opens the door to detailed molecular studies on the cells and new insight into the molecular basis for hearing, according to the researchers.
Stefan Heller of Stanford University School of Medicine said that is especially significant, because the "inner ear shelters the last of our senses for which the molecular basis is unknown."
Such understanding could also set researchers on a path to discovering new ways to prevent or correct hearing loss by encouraging hair cells' regeneration.
After all, the researchers say, our inability to regenerate lost hair cells is the major reason for the permanence of hearing loss as well as certain balance disorders.
Scientists have been left in the dark on the molecular basis for hearing in large part because hair cells are relatively scarce by comparison to other sensory cells, explained Heller.
Our inner ears harbour about 30,000 sensory hair cells in total in two different types, few of which can be dissected out of the inner ear and kept alive for study.
Heller's team long ago realized that one solution to this problem was to use stem cells as a source for generating new hair cells, and now they've got the recipe.
They have devised what they refer to as a stepwise guidance protocol for making the hearing cells, starting with either mouse embryonic stem cells or induced pluripotent stem (iPS) cells, which are stem cell-like cells derived from adult mouse cells.
The study was published in the latest issue of the journal Cell, a Cell Press publication.