CONTACT: JENNIFER CRONIN
2130 Medical Laboratories
Iowa City IA 52242
(319) 335-5661; fax (319) 335-9917
Release: May 5, 1999
UI study suggests promising treatment for diabetic
IOWA CITY, Iowa -- Pregnant women with diabetes must deal
with the costly and difficult tasks of checking their glucose levels and taking
insulin injections several times daily in an effort to ensure their babies
are born without birth defects. However, there may be a better way of handling
the blood glucose condition during pregnancies, according to results from
a University of Iowa study.
Stephen Hunter, M.D., Ph.D., UI assistant professor of
obstetrics and gynecology, and his colleagues are investigating whether a
transplant of specially encapsulated pancreatic islet cells can control a
woman's diabetes during pregnancy. Pancreatic islet cells produce insulin,
a hormone that becomes deficient in people with diabetes. The UI researchers
have already tested the islet cell treatment on mice with great success.
"Successful use of this treatment in pregnancies complicated
by diabetes would be a significant advancement for these patients and a major
breakthrough in the battle against diabetes-induced birth defects," Hunter
An estimated 1.5 million women of childbearing age in
the United States have diabetes. A diabetic pregnancy is one of the leading
causes of birth defects, Hunter said. A woman with diabetes is two to five
times more likely to give birth to a baby with a birth defect than a woman
without the condition.
Many researchers have investigated how to transplant the
pancreatic islet cells into people with diabetes as a way to treat the condition
permanently; however, there are problems with using the islet cells for lifelong
diabetes control because the body rejects the cells unless powerful anti-rejections
drugs are used.
To prevent rejection without the need for anti-rejection
drugs, investigators are encapsulating the pancreatic islet cells within a
gelatin. The material allows small substances such as glucose and insulin
to pass freely but prevents the large molecules and cells of the immune system
from interacting with the islet cells and thereby prevents rejection. Unfortunately,
the encapsulated islet cells do not survive for long periods of time because
the isolating material decreases oxygen supply to the cells. However, in the
case of a relatively short-term use, such as pregnancy, Hunter thought the
approach might work.
Hunter tested his hypothesis using mice. His results showed
that the mice treated with the encapsulated islet
cells had significantly lower blood glucose levels throughout their pregnancies
and were significantly less likely to give birth to pups with malformations
(3.0 - 5.4 percent in the treated diabetic mice versus 40 - 50 percent in
their untreated counterparts).
Hunter's study appears in a recent issue of the American
Society for Artificial Internal Organs Journal.
Although the results are promising, there is still work
to be done before researchers can test the treatment in humans, Hunter said.
Many of the treated mice experienced hypoglycemia. Hunter is not exactly sure
why this happened, but he speculated that it may involve an inability of isolated,
encapsulated islets to communicate with one another and coordinate the total
insulin secreted among them. Hunter and his colleagues are looking at how
to produce genetically engineered islet cells to avoid this problem as well
as how to improve the cells' use of oxygen and their ability to avoid rejection
without the use of a protective barrier.
Hunter also wants to find a better way to implant the
cells. In the mice, Hunter placed the cells directly into the abdomen's peritoneal
cavity. Hunter would like to devise a way to implant the cells under the skin
where doctors could remove the cells if complications arose.