Cells That Go Back in Time Lop off a newt's leg or tail, and it
will grow a new one. The creature's cells can regenerate thanks
to built-in time machines that revert cells to early versions of
themselves in a process called dedifferentiation. Researchers
who study this mechanism hope one day to learn how to induce the
same "cell time travel" in humans. If the cells go back far
enough, they become stem cells, which researchers believe hold
promise for treating many diseases. Stem cells, which are often
taken from embryos, are unformed and have the ability to become
many different types of cells. If researchers succeed in
inducing this cell time travel, they will also eliminate the
ethical issues surrounding embryonic stem-cell research, because
no embryos would be destroyed to obtain the cells. The research
is in its infancy, but a 2001 discovery jump-started the field
of study. Mark Keating, Christopher McGann and Shannon Odelberg
applied a protein extract derived from newts to mouse muscle
cells. To their su