A developmental biologist muses about stem cells and regenerative medicine, the ethics of it all and the possibilities.
Stem Cells Replace Hair Cells in Cochlea of Mice
In mammals, hearing loss is usually due to damage to the sound-sensing hair cells in the inner ear.
Originally, the hair cells were thought to be irreplaceable, but research in mice has shown that the supporting cells that provide structural support to the hair cells can turn into hair cells. If this technology can be applied in older animals, then it might provide a way to stimulate hair cell replacement in adults and treatments for deafness as a result of hair cell loss.
According to Albert Edge of the Harvard Medical School and Massachusetts Eye and Ear Infirmary, hair cell replacement definitely occurs, but does so as rather low levels. According to Edge: “The finding that newborn hair cells regenerate spontaneously is novel.”
Earlier work has shown that inhibition of the Notch signaling pathway increases the formation of new hair cells not from remaining hair cells but from nearby supporting cells that express a cell-surface protein called Lgr5.
When Edge and his team used small molecules to inhibit the Notch signaling pathway, even more support cells differentiated into hair cells, and the Lgr-5-expressing cells were the only supporting cells that differentiated under these conditions.
By combining these new findings about Lgr-5-expressing cells with the previous finding that Notch inhibition can regenerate hair cells, scientists should be able to design new hair cell regeneration strategies to treat hearing loss and deafness.
Professor of Biochemistry at Spring Arbor University (SAU) in Spring Arbor, MI. Have been at SAU since 1999. Author of The Stem Cell Epistles. Before that I was a postdoctoral research fellow at the University of Pennsylvania in Philadelphia, PA (1997-1999), and Sussex University, Falmer, UK (1994-1997). I studied Cell and Developmental Biology at UC Irvine (PhD 1994), and Microbiology at UC Davis (MA 1986, BS 1984).
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