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Pre-Transplant Procedure

 

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 pretreatment 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. 

 




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