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NZ research implants pig cells in human diabetics

NZ research implants pig cells in human diabetics

A New Zealand company is preparing to implant pig cells into people as an experimental diabetes treatment, though some scientists warn the risk of introducing a new virus to humans is too great.
Biotechnology company Living Cell Technologies says it will start work immediately to recruit eight patients with Type 1 diabetes to take part in cell implants from newborn pigs. The New Zealand government gave its approval last week.
The piglet cells will be implanted in the abdomen to manufacture insulin, company medical director Bob Elliott said. The cells will be coated in a seaweed-derived membrane to discourage the volunteers' immune systems from rejecting the foreign cells. The coated implant also means there is no need to use immunosuppressant drugs, he noted.
The cells produce pig insulin, which is very similar to human insulin, and replicates its effects by lowering blood sugar, Elliott said.
The harmful effects of Type 1 diabetes _ including blindness, premature coronary illness and limb amputation caused by poor blood circulation _ could be delayed by the treatment but would not be entirely eliminated, he said.
Elliott has run two previous trials, the first with six patients in New Zealand in 1995-1996. The other, in Russia with 10 patients, began in July 2007.
While five of the New Zealand patients either had the implants rejected or the pig cell insulin faded within a year, in one volunteer the implanted pig cells continue producing insulin 12 years after being implanted _ "proof of principle that this (methodology) can work," he said.
The Russian trial is only part way through, but Elliott said five of the patients had recorded measurable drops in the amount of insulin they need to inject _ one reported a 36 percent fall, another a 25 percent reduction _ and "very good insulin control."
One patient had reported going off all injected insulin for five months, he said.
A scientific paper on the trial is to be produced by the end of 2009, he added.
Scientists and ethicists are debating whether animal cells or organs should be transplanted into humans to improve treatments or deal with shortages of donated human organs.
One risk is that viruses that exist in pigs but not in humans could jump species, potentially causing new illnesses and _ in the worst case scenario _ new pandemics. Scientists say there are more than 100 pig viruses that can potentially transfer to humans. Elliott said recent research suggests the pig viruses thought to be most infectious for humans _ porcine endogenous retroviruses _ can be monitored and controlled.
Elliott said pig insulin has been injected to treat diabetes in humans for 50 years and, "nobody came to any harm."
"You are much more likely to get some nasty disease from an organ donation or an organ donor than you are from pigs," Elliott said.
Megan Sykes, an expert in immunology and cross-species transplants at Harvard Medical School, said it was too early to start human trials of the treatment because no scientific data from animal studies had been published, and because of the risk of a new virus spreading to humans.
"There should be preclinical studies that suggest it is going to work, and there's nothing in the public domain about this particular treatment that says it will," she told The Associated Press by telephone from Massachusetts. "That is an area of concern."
The risk of virus transmission could be minimized, but, "speaking for myself, I feel that ... to take that risk there should be a strong expectation of efficacy (shown in) preclinical studies," she said.
She said she believed New Zealand, with its strict regulatory framework for xenotransplantation, has the capacity to minimize risk arising from the human trial.
The study will use cells from newborn offspring of pigs recovered from Auckland Island south of New Zealand, where they had remained isolated from outside diseases for some 200 years.
Approving the research, Health Minister David Cunliffe said it would comply with World Health Organization requirements.
Conditions imposed on the trial include oversight by an independent safety management board and a favorable peer review by a leading international expert to be nominated by the Health Ministry.
Patrick Manning, president of the New Zealand Society for the Study of Diabetes, a group representing diabetes doctors, said proving pig cells safe and effective could overcome severe shortages of human cells.
The risk of infection by a pig virus was "extremely low, though it (is) premature to say the risk is absolutely zero," he said.
Only "pioneering research" studies such as that approved in New Zealand would truly determine the risk, he said.
The project is expected to begin by next March and run for 18 months, Elliott said.
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Updated : 2020-12-01 14:16 GMT+08:00