May 19, 2002.
A children's pathologist and a Dalhousie University biologist in Halifax are using fish cells to eliminate a form of diabetes in humans.
"Rarely does one call anything a cure but this would certainly be very close," said Jim Wright, a researcher with the Isaac Walton Killam Children's Hospital.
He and Bill Pohajdak are creating genetically engineered fish that produce human insulin in cells that would be transplanted into people to regulate their blood sugar levels. Mr. Wright said it would be used in the treatment of Type 1 diabetes, which occurs mostly in children but persists into adulthood.
With this type of diabetes, the cells in the pancreas that make insulin -- islets -- have been destroyed by the immune system, so the treatment involves surgically replacing the islets.
In mammals, islets make up just one per cent of the pancreas and are scattered throughout the organ, which makes them difficult to extract.
Human donations are also impractical because only about 5,000 pancreatic glands are available across North America a year. It takes two to three organs to produce enough islets for one transplant.
There are 1.5 million diabetics and up to 50,000 new patients are diagnosed each year.
In some bony fish, the islet tissue is anatomically separated from the rest of the pancreas, which makes it easier to harvest, Mr. Wright said. And the fish can be mass produced.
Mr. Wright, who has been involved in diabetes research for more than 20 years, said his team has already proved that fish islets cure diabetes in mice. The problem the researchers face now is that fish islets make fish insulin, which is not as effective as human insulin.
Mr. Wright and Mr. Pohajdak have made a fish that makes human insulin "but we haven't yet been able to stop the simultaneous production of fish insulin as well. Our fish make both right now."
The next phase in the project is to stop production of the fish insulin. Mr. Wright said researchers worldwide are close to perfecting that technique -- it's already been done in mice.
"Once they've done that, it will be reasonably easy" to get the fish to produce only human insulin, he said.
"If successful, the long-term consequences would be probably quite tremendous," Mr. Wright said.
Diabetics need several insulin injections a day.
The islet transplants would regulate insulin production and stabilize blood sugar levels. That's important, because fluctuations in blood sugar levels increase the patient's chances of developing long-term complications, such as heart attacks, kidney disease and blindness.
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