Capsules of insulin produced in genetically modified lettuce could
hold the key to restoring the body's ability to produce insulin and help
millions of Americans who suffer from insulin-dependent diabetes, according
to University of Central Florida biomedical researchers.
Professor Henry Daniell's research team genetically engineered tobacco
plants with the insulin gene and then administered freeze-dried plant cells
to five-week-old diabetic mice as a powder for eight weeks. By the end of
the study, the diabetic mice had normal blood and urine sugar levels, and
their cells were producing normal levels of insulin.

Those results and prior research indicate that insulin capsules could
someday be used to prevent diabetes before symptoms appear and treat the
disease in its later stages, Daniell said. He has since proposed using
lettuce instead of tobacco to produce the insulin because that crop can be
produced cheaply and avoids the negative stigma associated with tobacco.

The National Institutes of Health provided $2 million to fund the UCF
study. The findings are reported in the July issue of Plant Biotechnology
Journal.

Insulin-dependent, or Type 1, diabetes is an autoimmune disease in
which the body's immune system attacks and destroys insulin and
insulin-producing beta cells in the pancreas. Insulin is a hormone that is
needed to convert sugar, starches and other food into energy.

Insulin typically is given through shots and not pills so the hormone
can go straight into the bloodstream. In Daniell's method, plant cell walls
made of cellulose initially prevent insulin from degrading. When the plant
cells containing insulin reach the intestine, bacteria living there begin to
slowly break down the cell walls and gradually release insulin into the
bloodstream.

"Currently, the only relief for diabetes is a momentary relief,"
Daniell said. "Diabetics still have to monitor their blood and urine sugar
levels. They have to inject themselves with insulin several times a day.
Having a permanent solution for this, I'm sure, would be pretty exciting."

Though produced in lettuce, the insulin would be delivered to human
patients as a powder in capsules because the dosage must be controlled
carefully.

If human trials are successful, the impact of Daniell's research could
affect millions of diabetics worldwide and dramatically reduce the costs of
fighting a disease that can lead to heart and kidney diseases and blindness.

About 20.8 million children and adults in the United States, or about
7 percent of the population, have Type 1 or 2 diabetes, according to the
American Diabetes Association.

The number of Americans with diabetes is projected to double by 2025,
according to a study released last month by the National Changing Diabetes
Program during a congressional briefing. That study by Mathematica Policy
Research Inc. also reported that one of every eight federal health care
dollars , $79.7 billion out of $645 billion -- is spent on treating people
with diabetes.

"Diabetes is a big health and financial burden in the United States
and in the rest of the world," Daniell said. "This study would facilitate a
dramatic change because so far there is no medicine that will cure
insulin-dependent diabetes."

Daniell's method of growing insulin in plants is similar to what he
used for an earlier study to produce anthrax vaccine in tobacco. In the
earlier study, which also involved mice, Daniell showed and the National
Institutes of Health confirmed that enough safe anthrax vaccine to inoculate
everyone in the United States could be grown inexpensively in only one acre
of tobacco plants.


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