Transplants And Diabetes Essay, Research Paper

Three Toronto scientists have developed an organ

transplant procedure that could, among its many

benefits, reverse diabetes. The procedure was

developed by Bernard Leibel, Julio Martin and

Walter Zingg at the University of Toronto and the

Hospital for Sick Children. The story of their work

began in 1978, when they delved into research

which had never before been tried. They wanted

to determine if the success rate of organ

transplants would increase if the recipient was

injected with minute amounts of organ tissue prior

to the transplant. The intention was to adapt the

recipient to the transplanted tissue and thereby

raise the threshold of rejection. In the case of the

diabetes experiment, this meant injecting rats with

pancreatic tissue before transplanting islets of

Langerhans, small clusters of cells scattered

throughout the pancreas which produce insulin,

glucagon, and somatostatin. In their first

experiment, outbred Wistar rats were injected

with increasing amounts of minced pancreas from

unrelated donor rats for one year while a control

group was left untreated. Then both the treated

and control groups received injections of

approximately 500-800 islets of Langerhans from

unrelated donors. Of the five treated animals, two

became clinically and biochemically permanently

normal. Six months later, Martin examined the

cured rats and found intact, functioning islets

secreting all of their hormones, including insulin.

None of the controls were cured. Encouraged by

their first results, Leibel, Martin, and Zingg

decided to repeat the experiment with rats with

much stronger immune barriers (higher levels of

rejection). Seven rats out of nine were cured. "We

set up a protocol and worked patiently with small

numbers," says Leibel, "but the results are

indisputable." In addition to reversing diabetes,

there are two other benefits to the pre-treatment

procedure, according to the scientists. The first is

that the pancreas produces all the other hormones

of a normal pancreas, not just insulin. The second

benefit is that the transplant recipient doesn’t have

to take immunosuppressive drugs, which are so

toxic for diabetics. At present, diabetics who

receive a transplanted pancreas must take such

drugs for life. The scientists eventual goal is a

human trial, but they admit it will be years before

such a study is conducted. The obvious benefit for

diabetics, if human trials prove successful, would

be a return to a normal life without dietary

restrictions or insulin shots. But to Liebel, the most

important reason to continue research is to

eliminate the debilitating, degenerative diseases

such as kidney, eye and heart failure that

eventually plague the aging diabetic.