San Antonio, TX (6/11/00)- The Holy Grail of diabetes research,
an unlimited source of functional, insulin-producing beta-cells is now a reality,
announced researchers at the American Diabetes Association's 60th annual meeting.
The new ability to produce these cells, missing in patients with insulin-dependent
diabetes, offers the promise of effective treatment and possible cure for
the disease without depending on the donation of organ tissue, always in short
supply.
A
research team from the University of California in San Diego reported the
creation of an immortalized cell-line that produces the precious human beta-cells
in virtually unlimited numbers. The finding couldn't come at a better time,
as clinical researchers have also recently announced improved success with
beta-cell transplantation in patients with Type I, insulin-dependent diabetes.
The new laboratory technique could assure a reliable supply of the insulin-regulating
cells for patients who need them.
left: Dr.
Fred Levine and colleagues in the lab
"Even if you had unlimited success with tissue transplantation, there is
simply not enough donor tissue to treat the millions of people who have diabetes.
We have now been able to create an immortal human cell line, and have demonstrated
in mice that these cells are functional when transplanted, secreting insulin
in response to glucose stimulation.," said Fred Levine, M.D., Ph.D.,
associate professor at the UCSD Cancer Center and the Whittier Institute in
San Diego, whose laboratory reported the successful results
The new cell line was created by hybridizing human beta-cells with an line
of cancer cells, a standard approach for creating immortal, protein producing
cells. It took the researchers eight years to develop the technique for making
these particular cells. The research presented at the ADA conference involved
studies with mice. In those studies, the experimental beta-cells responded
to glucose by producing sufficient insulin in the animals. Human studies are
still some years away, Levine cautioned.
Some 16 million people in the US alone have diabetes, primarily of the Type-II,
non-insulin-dependent variety. If a sufficient supply of beta-cells were available,
both Type I (insulin-dependent) and Type II patients could also benefit from
cell transplantation.
Important Progress on the Transplant Front
Until
now, transplanting beta-producing cells into patients with diabetes has involved
either transplanting a donor, islet-cell producing pancreas, or, direct infusion
of islet-cells. These methods have been used with some success for several
years, but were hampered not only by a shortage of cells for transplantation,
but also by interaction with the patient's immune system requiring the use
of immunosuppressive drugs. Researchers from Edmonton, Alberta, Canada reported
important progress on the front recently with a modified approach. Developed
by Dr. James Shapiro, the 'Edmonton Protocol' uses a novel steroid-free combination
of three drugs--Tacrolimus, Sirolimus and Daclizumab--which together prevent
rejection of the transplanted islets and also stops the autoimmune diabetes
from returning. The protocol also uses more islets and transplanted them immediately
rather than putting them in an incubator for several days after they are removed.
That work is now being expanded to clinical trials across North America, under
the auspices of the Immune Tolerance Network, a consortium of research centers.
right: a healthy
islet cell (click for transplant animation)
Other approaches now being investigated in the area of islet-cell transplantation
include the concomitant use of bone marrow stem cells during transplantation,
the use of monoclonal antibodies to modulate the immune response, and the
use of genetic engineering techniques to deliver other potentially useful
anti-rejection proteins.
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