Islet-Stem Cell Transplants Result in Insulin Independence in New Clinical Trial
Miami, FL (September 21, 2005) -- The first of only six patients who will be transplanted with bone marrow stem cells and insulin-producing cells (islets) in a newly launched clinical trial is already off insulin and doing well, report scientists at the Diabetes Research Institute at the University of Miami Leonard M. Miller School of Medicine. The recipient received her transplant in June.
“This is the first time we have obtained insulin independence following a single infusion of insulin- producing cells and two infusions of stem cells (known as CD34+ hematopoietic progenitor cells) purified from the bone marrow of the same donor,” explains Camillo Ricordi, M.D., scientific director and chief academic officer of the Diabetes Research Institute (DRI).
The new clinical trial is a variation of the DRI’s pioneering islet cell transplantation technique. In addition to the islet cells which are harvested from a donor pancreas at the DRI’s state-of-the-art cellular processing facility, physicians also transplant bone marrow stem cells from the same donor in the hope that they can achieve insulin independence and eliminate the patient’s need for anti-rejection drugs. “Since we performed the first successful series of islet transplants in 1990, we’ve concentrated our efforts on the development of strategies to decrease and eventually eliminate the need for lifelong treatment of the recipients with anti-rejection drugs. It is still early to determine whether this specific trial will allow us to achieve this ultimate goal, but we are very enthusiastic about this initial success,” adds Ricordi.
“Unlike heart or liver transplantation, recipients of an islet transplant are not in an immediately life-threatening situation, so they must carefully weigh the decision to take potentially harmful anti-rejection drugs for life in order for their islets to survive,” says Rodolfo Alejandro, M.D., director of clinical islet transplantation at the UM Diabetes Research Institute.
The study procedure calls for the use of multiple donor tissues. When a donor pancreas becomes available, investigators will also simultaneously harvest 10 to 12 vertebrae from the same donor, from which they will extract bone marrow stem cells.
The idea behind the study is to create “chimerism,” a condition in which the stem cells from the donor immune system will co-exist with the recipient’s own immune cells, re-educating the recipient immune system not to reject the transplanted islet cells.
“If the trial is successful, it will actually be possible to identify the presence of cells from the donor throughout the recipient’s body,” explains Norma Sue Kenyon, Ph.D., associate director of Research and Program Development at the DRI, who will periodically test patients to determine their level of “chimerism” and track levels of immune response to donor tissues.
The first study patient, who has now been off insulin for three months, will continue to take anti-rejection drugs for one year, at which time she will be evaluated to see if sufficient levels of “chimerism” have been developed, and if her anti-rejection medications can be reduced and eventually withdrawn altogether.
Jeanne Antol Krull
UM Leonard M. Miller School of Medicine
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