scientists traced the loss of hair color to the gradual dying off of
adult stem cells that form a reservoir that spawns a continuous supply
of new pigment-manufacturing cells, called melanocytes, that give hair
its youthful hues. Not only do the non-specialized stem cells become
depleted, they also progressively make errors, turning into fully
committed pigment cells in the wrong place within the hair follicle,
where they are useless for coloring hair.
The new findings won’t lead to a scientific alternative to hair dyes
any time soon, if ever, even if they do solve a longstanding puzzle
about the underlying mechanism of graying. Of more interest to the
researchers is the pattern of cellular signals that triggers the death
of pigment stem cells, since melanoma is dangerous for the opposite
reason –melanocytes proliferate uncontrollably to form tumors and are
hard to kill with treatment.
“Preventing the graying of hair is not our goal,?emphasizes David E.
Fisher, MD, PhD, director of the Dana-Farber Program in Melanoma, and
senior author of the Science paper. “Our goal is to prevent or treat
melanoma, and to the extent this research is revealing the life cycles
of melanocytes, which are the cells that become cancerous in melanoma,
we would love to identify a signal that would make a melanoma cell stop
growing.?Fisher and the report’s lead author, Emi K. Nishimura, MD, PhD, also of
the melanoma program, are in the Department of Pediatric Oncology at
Children’s Hospital Boston as well as at Dana-Farb