Pig cells hope for diabetes cure

When Professor Bob Elliott boards a plane from New Zealand to Moscow later this month, he will be taking extra care of his hand luggage. In a secure container he will be carrying millions of insulin-producing pig islet cells. Many believe they have the potential to transform the lives of patients with Type 1 diabetes. A trial about to start in Russia will help determine if this is true.

Go back 10 years, and a similar trial took place in Auckland, New Zealand, where Professor Elliott is medical director of the biotech company Living Cell Technologies. He said the trial was running without problems, but they felt compelled to stop.

"It was a purely precautionary measure because of limited research suggesting pig retroviruses could infect patients," he said. "Now we are confident this isn't the case. After more animal studies and carefully following patients for nearly a decade, the scare has gone."

It means the research is back on. It involves transplanting millions of pig islet cells into each patient. For the study, the cells are poured through a funnel into the abdomen after checking the condition of the intestines with a laparoscope. In the future, it may only require a simple needle puncture. Either way, it will take just a few minutes.

The islet cells should start to produce insulin in response to the body's demands. This control is lacking in patients with Type 1 diabetes. It means they need insulin injections to keep blood sugar levels constant. Otherwise they face serious health consequences - falling unconscious, or in the long term, blindness or organ damage.

Islet cell transplantation is already being tried with human cells, but there are big differences. Human cells are in limited supply, but pig herds could be expanded to meet demand. There is also the issue of immunosuppression. Anti-rejection drugs are needed with human cell transplants, but Professor Elliott said that is not the case with pig cells.

The clusters of cells are protected by encapsulation in a seaweed-based gel. The company believes it is leading the world with this technology.

Professor Elliott said: "If you need anti-rejection drugs the treatment isn't worthwhile - the side effects can be unpleasant, it would be getting rid of one problem and introducing another." T

The study's aim is at least a 25% reduction in need for insulin to maintain blood sugar control. Measurements will be taken at six months and one year, with patients then observed for the rest of their lives.

The researchers hope the reduction will be much greater in some, but even a 25% drop could reduce the dangerous fluctuations in blood sugars to a significant extent.

This is what patients like 51-year-old Michael Helyer really want. He took part in the first New Zealand trial. He received only a third of the dose now thought to be necessary, but experienced a 30% reduction in insulin requirement. Ten years later, some of the pig cells are still producing insulin. Mr Helyer leads a busy life running his own music store and is certain the treatment has helped.

"It's not about having fewer injections, it's about getting more control. You can't live a normal life if you're in fear of (blood sugar) levels getting too high or low all the time."

The use of pig islet cells has been tried before, but with different methods. In Sweden, pig foetal cells were injected into a vein with immunosuppressants, but there was little success. In Mexico, cells were transplanted into tubes under the skin, along with Sertoli cells from piglet testes, which are thought to offer a form of immunoprotection. A trial of 12 patients showed some improvement, but the results of further patients have not yet been documented. The procedure has since been stopped.

With this chequered past, it is not surprising there is some scepticism. Jo Brodie, Islet Project Co-ordinator at Diabetes UK, agrees the research has potential, but also has reservations. "A great deal more work is needed. Also, there are still ethical and safety issues that need addressing."

Living Cell Technology is going to great lengths to address these. Not least in its source of pig cells. They come from a herd isolated on a remote subantarctic island. They were abandoned by a sealing ship 200 years ago. Some of the descendants of this pure breed were transported to New Zealand to live in "pig palaces". These are bio secure facilities to ensure the pigs are totally disease-free. But the company is limited in where it can conduct its research.

There is a moratorium on the use of animal tissue in humans (xenotransplantation) in countries like Canada and Australia. Others, such as New Zealand, are currently deciding whether further trials can take place. But Professor Elliott is comfortable with Russia for the trial.

Surgeons there are experienced in xenotransplantation, and a growing clinical research industry means international regulatory standards are in place. He believes the study will provide data other countries won't be able to ignore.

He just wants to get started. This is his life work. "This is what all my diabetes patients want. If the trial is a success, we will be inundated."