Baylor researchers show way to diabetes cure with gene therapy
HOUSTON (April 21, 2003) A gene therapy developed by researchers at Baylor
College of Medicine has apparently cured diabetes in mice by inducing cells in
the liver to become beta cells that produce insulin and three other hormones.
"It's a proof of principle," said Dr. Lawrence Chan, professor of medicine
and molecular and cellular biology as well as chief of the division of diabetes,
endocrinology and metabolism at the College. "The exciting part of it is that
mice with diabetes are 'cured.' "
In the research, which is described in a report in Nature Medicine's online
edition today, Chan and his colleagues used the NeuroD gene, a transcription
factor that induces the liver to produce cells that make insulin and the three
hormones associated with the pancreas' endocrine system.
The gene was attached to a so-called "gutless" adenovirus from which all
toxic genes had been removed. This viral vector is a very efficient way to
introduce genes into liver cells. Alone, NeuroD partially corrected the disease
in the diabetic mice. Combined with a beta cell growth factor called Btc, the
gene therapy complete cured the mice's diabetes for at least four months.
An added benefit is that the cells in the liver also produce glucagon,
somostatin and pancreatic polypeptide, which may play a role in controlling
insulin production and release.
"Until now it has not been possible to induce the formation of islets by any
gene therapy approach," said Chan.
It does not mean that the treatment can be used in people immediately.
"It's farther from people than I would like," he said. He knows of no
stumbling blocks to its effectiveness in people.
The main stumbling block is the vector or virus used to take the gene into
the cells. Chan and his colleagues used the safest viral vector available today,
but he expects even safer ones to be available within the decade.
"We want to use the safest vector possible," he said.
The treatment has advantages over transplant of islet cells, the insulin
producers in the pancreas, because it avoids the lifelong use of powerful
immunosuppressive drugs and eliminates the need to find a compatible donor.
Chan credits one of his postdoctoral students, Dr. Hideto Kojima, with much
of the work in developing this protocol.
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