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Diabetes Patients to Be Implanted With Pig Cells In New Clinical Trial

October 22, 2008 01:55 PM
by Emily Coakley
In a new clinical trial, people with Type 1 diabetes will be injected with insulin-producing pig cells, raising hopes for a cure and concerns over xenotransplantation.

Pig Potential Investigated for Years

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Research involving the pig cells started more than a decade ago, but was stopped by New Zealand officials over concerns about transmitting viruses from pigs to people. Bob Elliott of Living Cell Technologies pioneered the research. 

In approving the trial, David Cunliffe, New Zealand’s health minister, said, “It remains clear to me that any such trial will always carry a very low residual risk, so the key issue has always been whether this risk is sufficiently small and can be successfully managed,” according to the Daily Telegraph.

The pigs that will provide the cells come from a quarantined herd that has lived in isolation for 200 years on the Auckland Islands.

The newspaper described the procedure: “Islet cells from the pancreas of pigs are coated with a seaweed gel and implanted into the abdomen of patients to manufacture insulin and help control their blood sugar levels.”

Sophie Foster, 11, told the New Zealand Herald she would consider having the procedure if it were approved. She now uses a pump to help regulate her insulin levels.

“Diabetes is quite a pain for me, because at my age a lot of people have sugary drinks and unhealthy food and I’m stuck with fruit and vegetables. I would like to eat other things, probably stuff like lollipops,” Foster told the Herald.

A small clinical trial involving pig cells and people with Type 1 diabetes is underway in Russia, though the volunteers there have received smaller doses than those in New Zealand will receive, the Daily Telegraph said.

Background: Efforts to cure Type 1 diabetes

In 2002, the journal Nature Medicine reported on doubts surrounding another experiment involving pig cells and diabetes.

Researchers said that one teen who received the cells didn’t use insulin for more than a year after the procedure, while a dozen others needed less insulin. Another dozen didn’t see any changes to their insulin requirements.

The trial raised concerns for a number of reasons. It was conducted in Mexico, “outside internationally recognized regulatory conditions,” Nature Medicine said, and the data lacked evidence of a particular peptide that should have been present in the subjects’ blood samples if the pig cells were producing insulin.

Nature Medicine concluded, “At best, the scientific community has expressed a guarded reaction to the potentially groundbreaking work.”

Related Topic: Xenotransplantation

Some say xenotransplantation could solve the chronic supply shortage that hinders organ donation.

“Xenotransplantation, or transplanting organs and tissues from a different species, has generated considerable interest as a potential solution to the great unmet need,” wrote William Beschorner, a professor at the University of Nebraska Medical Center and chief scientific officer for a company called Ximerex Inc., in a 2006 article on eMedicine. Ximerex is a company that is working to grow human cells in pigs.

Pigs aren’t the only animals involved in xenotransplants, though Beschorner argues they are ideal for human transplants.

“Many pig organs are similar to their human counterparts in size, anatomy, and physiology. Numerous pigs can be produced quickly under standardized, clean conditions. In addition, pigs can be readily modified, as their genes can be added or removed. Moreover, human cells can be grown in the pig,” he wrote.

Beschorner also said that the risk of pig cells transmitting porcine endogenous retroviruses (known as PERV) to people, causing a major public health crisis, is “infinitesimal.”

“The potential medical value of xenotransplants far outweigh the minimal potential risk of PERV and should not be a barrier to xenotransplantation,” he wrote.

But the risk of PERV is only one potential problem with xenotransplantation. The PBS show “Frontline” explored animal rights concerns in a 2001 piece called “Organ Farm.”

David White, research director at a British company called Imutran, told “Frontline”: “We have to be frank about this: We are exploiting these pigs. But I believe it’s far more justifiable to exploit these pigs in order to save people’s lives than for the production of food.”

Tissue from baboons has also been used in humans. According to the site HIV and Hepatitis, in 1995, a man with “advanced AIDS” received a baboon bone marrow transplant. Though the marrow didn’t do what doctors had hoped, the man was still alive eight years after the procedure and suffered no “adverse events” from the transplant.

Reference: Diabetes Web Guide

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