| Unexpectedly, insulin cells seen
to self-replicate
NEW YORK (Reuters Health) - The insulin-producing beta cells in
the pancreas retain the ability to proliferate, investigators at
Harvard University in Cambridge report.
This finding contradicts the theory that adult stem cells are the
primary source for maintaining and repairing pancreatic beta cell,
Dr. Douglas A. Melton and associates explain in this week's issue
of the science journal Nature.
Thus, for people with type 1 diabetes -- who lack sufficient insulin
-- "a useful clinical direction would be to find a way to boost
the proliferative capacity of those beta cells, to restore insulin
production in such patients," Melton comments in a university
statement.
But for patients with no residual beta cells, "the only source
of new beta cells is probably going to be embryonic stem cells,
because there don't appear to be adult stem cells involved in regeneration,"
he added.
Melton's group developed a way to tag the DNA of insulin-producing
cells in mice. The number of labeled beta cells remained stable
for up to 12 months, and there was no dilution of labeled cells
over time.
Because there were no new untagged insulin cells, "the results
are not consistent with beta-cells forming from stem or progenitor
cells," the investigators write.
In animals in which part of the pancreas was removed, new beta
cells were the product of self-duplication.
Beta cells for transplantation into diabetic patients might be
obtained from deceased donors, Dr. Ken Zaret, of Fox Chase Cancer
Center in Philadelphia, points out in an accompanying editorial.
However, embryonic stem cells may still be the ideal source, he
proposes, because the number of beta cells obtainable from donors
is small and because stem cells are less likely to have accumulated
abnormalities.
SOURCE: Nature, May 6, 2004.
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