Diabetes News
Week of July 16, 2000 |
|
   
In previous newsletters, we have reported on the diabetes
research being conducted in Edmonton, Canada. In this study,
eight people with severe diabetes have been treated with
islet-cell transplants, and have remained off insulin for one
year. A recent meeting of Transplant 2000 in Chicago included an
update.
This month's issue of Diabetes Interview (vol 9, no 7, issue
96, pages 37-39, July 2000) includes the update. Dr. James
Shapiro describes the "Edmonton Protocol." Study
participants include eight people between the ages of 29 and 53
who have severe diabetes. They were all given transplants of
islet cells from donors. Each participant required 8,000-10,000
islet cells per 10 kilogram of weight, which created a need for
two donor pancreases for every participant. The participants
were then given a regimen of three different drugs to prevent
rejection, but did not require prednisone which can have more
extensive side effects. So
far, the participants have been healthy and insulin-free for
about eleven months.
In the near future, the Edmonton Protocol will be repeated in
forty centers in the United States, and forty centers in Europe.
Researchers in Europe will probably have an easier time of it,
as the policy in most European countries is that everyone is a potential donor unless they
specify that they do not want to donate organs/tissues at the
time of their death. This is in contrast to the policy in the
United States, in which people are not considered donors unless
they sign an agreement stating that they do want to be donors.
When the procedure requires two pancreases for every
participant, the number of available donors plays a huge role in
the success of the treatment.
Doctors also specify that cells from the donor pancreas must
be extracted quickly in order to have the best results.
Transplants that worked the best were from pancreases that were
preserved for less than eight hours. Pancreases preserved for
more than twelve hours are unusable.
The Edmonton research has been incredibly successful thus
far, and offers hope in the elimination of diabetes for those
who are willing to be exposed to the increased risk of cancer
and infection currently required of a therapy which suppresses
the immune system.
Genetically-Engineered Cells Produce
Insulin
Doctors have already shown that islet-cell transplants can
sometimes enable people with diabetes to produce insulin. The
recent progress in Edmonton, Canada, where eight out of eight
cadaver transplants were performing well after several months is
a good example. However, the problem with this treatment is that
there is simply not enough donor tissue to go around. But in a
new study, doctors have successfully created insulin-producing
cells in the lab.
Doctors at the University of California at San Diego
presented their findings at the American Diabetes Association
meeting (Diabetes, vol 49, supplement 1, abstract 127, 2000).
Their methods involved the introduction of a promoter oncogene,
which then stimulates cells to produce insulin. The promoter
oncogene is transplanted into fibroblasts, which are common
cells that produce connective tissues in the skin, tendons, and
blood vessels. This is opposed to the transplantation of
pancreatic cells, which are found only in limited quantities in
the pancreas.
This type of transplant had been performed before, but was
largely unsuccessful because the oncogene worked too well, with
the production of insulin-producing tumors within the
fibroblasts and the development of severe hypoglycemia in
animals. In this latest experiment, doctors allowed enough
islets to be formed and then injected a protein designed to
destroy the oncogene after its job was done.
The study was successfully performed in mice, giving doctors
hope that this method might be used to treat diabetes in people
in the future with a readily available source of
insulin-producing cells. Another advantage of this type of
treatment is the fact that a person would receive fibroblasts
from his/her own body, so that immune-suppressant drugs
would not be necessary. The next step would be to replicate the
experiment in larger animals, and then move on to human studies.
Treatment For Foot Ulcers Approved By FDA
One of the more dangerous complications associated with
diabetes is that of diabetic foot ulcers. These are often very
slow to heal, and if left untreated, can even lead to
amputation. A new product was recently approved by the FDA in
the treatment of these foot ulcers, and has been proven
effective in studies.
In a recent article, we reported on Apligraf, which is a
human skin equivalent used to layer over wounds to speed the
healing process. Apligraf was approved by the FDA in 1998 for
use in the treatment of leg ulcers that had not healed after
more than one month with conventional treatment. In June of this
year, the FDA approved the use of Apligraf to treat diabetic
foot ulcers which have not healed after three weeks.
In a study published in the Archives of Surgery 2000 (Volume
135, pages 627-634), doctors at Mount Sinai Medical Center in
New York showed that Apligraf effectively healed the foot ulcers
of seven in ten people with diabetes who participated in the
study. Additionally, seven of thirteen people with leg ulcers
healed completely. Most people only required one
treatment with Apligraf.
The FDA's expansion of the use of Apligraf is good news for
people with diabetes who have foot ulcers, and offers hope for
limiting the damage and disability associated with this dangerous complication.
The immune system works by recognizing substances that are
foreign to the body and destroying them to prevent infection.
However, scientists have not been exactly clear on the method
that the immune system uses to determine which cells are foreign
and which cells belong to the body. A recent study provides a
better theory about how it is done.
Scientists at the Washington University School of Medicine in
St. Louis have published the results of their research in the
journal Science (vol 288, issue 5473, pages 2051-2051, June 16,
2000). They show that all cells in the body have a receptor on
their surface called CD47. This receptor acts as a
"password" so the cell may be recognized by the immune
system.
Researchers showed that cells that did not have the receptor
were broken down by red blood cells almost immediately. In their
experiment, scientists bred mice without the CD47 receptor. Then
they injected cells from these mice into normal mice. They found
that the red blood cells without the receptor were broken down
within 24 hours, and were no longer detectable in the
bloodstream.
This research may provide a reason for diseases in which the
body destroys some part of itself, such as occurs in Type 1 diabetes,
certain anemias, and
arthritis. Scientists hope that further research into CD47 will
provide ideas for treatment of these diseases.
Easier Meal Adjustment With Insulin Pumps
The advantages of using an insulin pump are numerous, but one
of the most prominent of these is the fact that pumpers can
customize their insulin doses and therefore establish more
control.
The American Association of
Clinical Endocrinologists has recently published a
report showing that people who use pumps have better control of
their blood sugar levels partially because they are able to
adjust mealtime doses. The study was conducted for fourteen
months, and showed that people were able to better control their
Hb1c levels without weight gain when they made adjustments based
on their meals.
Information provided by The Diabetes Mall @ http://www.diabetesnet.com
Books, gram scales, and more: (800) 988-4772 or (619) 497-0900
Copyright © 2000 by Diabetes Services, Inc
Email Webmaster
with suggestions or problems.
|
