When people lose fingers in accidents,
fires, or combat, their only option has been to learn to function as best they
can. Often, it’s impossible for people to brush their teeth, grip a pen, or
use a hand tool.
And yet, growing a new finger — or even
an entire hand or an arm — isn’t a problem for certain other creatures, such as
salamanders, cockroaches, starfish, and a certain strain of mice. Scientists
are now unlocking the mystery of how these species regenerate limbs, and making
thrilling progress toward giving humans the same power.
According to an Associated Press report,1 a team of scientists is researching
tissue regeneration in salamanders and newts. When a salamander loses an arm,
it doesn’t grow a scab over the injured area. Instead, it produces a knob of
cells called a blastema. The blastema then develops into a new arm. In fact,
scientists have found that if they move the blastema from the site where the
salamander lost an arm to a new location, such as the creature’s back, it will
grow a new arm on its back.
They’ve also discovered how to make
salamanders grow extra arms. First, they make a small cut on a salamander’s
arm, then they re-direct a nerve to the new site, along with skin cells from
the wounded arm, so a blastema forms in the new location, and then a new arm
grows.
As the Chicago Sun-Times2 points out, a human
fetus can grow entire limbs and heal wounds without a scar. When open-heart
surgery is performed on a fetus before birth, the baby is born without a chest
scar.
The genes for tissue regeneration seem to
get switched to “off” after birth. If a person loses a limb, he grows scar
tissue over the wound, but the limb never regrows.
Intriguingly, scientists have found that
newts and humans have the same genes for growing limbs, but in newts they are
never switched off. By cutting off the limbs of newts and then studying how
they grow back, researchers hope to figure out how to turn on the genes for
regrowing limbs in humans.
DARPA is funding the project with up to
$15 million, with team members located at the University of Pittsburgh, the
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