Pig cell procedure spurs diabetes study

By SIMON COLLINS science reporter

Pioneer British transplant surgeon Sir Roy Calne plans to investigate the apparent breakthrough in diabetes treatment by Auckland research company Diatranz and Mexican surgeon Rafael Valdes.

In 1968 Sir Roy became the second person in the world to conduct a successful liver transplant.

Last December he examined Dr Valdes' 12 Mexican patients who were given transplants of Diatranz' insulin-producing pig cells, and confirmed that one girl has been able to stop taking insulin injections completely for the past five months.

But Sir Roy, who trained Dr Valdes at Britain's Cambridge University, said in Auckland yesterday that the long-term effect of the transplants was still unknown, and he wanted to test the procedure in animals.

"I thought this was some extraordinary biological phenomenon and didn't fit in with standard technology, therefore most people don't believe it," he said.

"When something doesn't fit in with the standard technology, people either say it's not true or it's very interesting. I think it's very interesting. But work needs to be done."

He said the most unusual aspect of the Mexican trial is that the 12 teenagers were not given any drugs to suppress their immune systems, which would normally destroy any cells from other animals.

Instead, the insulin-producing islet cells from newborn pigs were inserted in cigarette-sized capsules just under the skin, using sertoli cells from the testicles to protect the foreign cells from attack by the immune system.

"No one really knows what they do, but it's been known for many years that the testicles are a privileged situation for transplantation.

"You can transplant tissues into the testicle which do not get rejected," he said.

"So in these Mexican patients, they have had islets that produce insulin and these sertoli cells. My impression is that the sertoli cells are the central factor in why they have done well."

Sir Roy said it was also unusual to insert the pig cells just under the skin, instead of next to the liver.

He is negotiating a collaborative research project with Diatranz medical director Bob Elliott to test variations on the procedure in animals - initially pigs and rats.

"We are hoping to study what happens, to see what the optimum numbers of sertoli cells are vis-a-vis the islets to get the best results."



"I would also like to study putting the same islet/testicle cell mix into the abdomen where they would go first to the liver."

He expects to do the research - which will take about two years - at the National University of Singapore, where he is a visiting professor.

Though animal/human transplants would be restricted under legislation now before Parliament, Sir Roy said "a cautious continuation" of human trials would also be sensible. "But it needs to be studied very carefully," he said.

"We don't know how long this lasts, or if it's a temporary success in some of the patients.

"As to whether it's a lasting one, we don't know at all. That's one of the things we'd like to study in animals."

In the long term, Diatranz believes the procedure may provide a cure for the world's 15 million Type 1 diabetics, who have to inject insulin several times a day.

nzherald.co.nz/health