Living Cell Technologies announced that the first patient in their trial to receive a transplant of insulin producing porcine cells is doing well, and has reduced his insulin dose by 30%. Great news! A few months ago I read about the start of LCT’s trial, and wrote about it for The Faster Times. I’m re-posting the article here in my blog. I’m curious to hear your thoughts on xenotransplantation.
The Beast Within: Experimental Diabetes Treatment Infuses Pig Cells Into Humans
originally posted on The Faster Times
I first heard about xenotransplantation as a child. In 1984, the issue caused great uproar when a dying infant in California, Baby Fae, received a heart transplant from a baboon. Baby Fae lived only 20 days with her baboon heart.
I recall talking to other kids in my elementary school about Baby Fae. The story fascinated and horrified us at the same time. I didn’t know then the really disturbing fact about the Baby Fae case, that her doctor had given her a baboon heart without first trying to find a human heart. And I didn’t know then about issues of medical ethics and consent, or about the risk of animal viruses being transferred to humans. All I knew was that the story of Baby Fae was devastating, and more than that, something about it felt innately wrong.
I thought of Baby Fae a few days ago while reading about a New Zealand biotech company, Living Cell Technologies, which last week began an experimental diabetes treatment that will implant islet cells from newborn pigs into eight human volunteers. The porcine cells are encapsulated in a seaweed-derived membrane in order to discourage the volunteers’ immune systems from rejecting them. And because of the encapsulation, immunosuppressant drugs will not be used.
The implanted cells produce pig insulin, which is very similar to human insulin. In fact, until the advent of synthetic insulin, pig insulin was used to treat humans. Living Cell Technologies hopes the porcine cells, which are implanted via infusion into the volunteers’ abdominal cavities, will be able to delay the complications of Type 1 diabetes, though the medical director of the company, Professor Bob Elliott, acknowledges that the treatment is not expected to eliminate all of the symptoms. Type 1 diabetes is an autoimmune disorder that destroys the insulin-producing cells of the pancreas. Insulin is the hormone that allows glucose to move from the bloodstream into the cells, where its energy is put to use. Without insulin, glucose remains locked outside the cells and they starve.
I have diabetes, and for a moment I flashed on the idea of having porcine cells infused into my stomach. The thought gave me the chills. I got the same feeling I’d had when I thought about Baby Fae with a baboon heart, something about the creepiness of cross species transplants, something that just isn’t right. (I thought perhaps my anti-pig feelings stemmed from the fact that I grew up in a Kosher home, so I asked myself if I’d feel the same way about cow cells. Yes. I love cats so I thought about being infused with cat cells. I’ll admit, cat cells bother me much less than pig or cow cells, but I still don’t like the thought of it.)
It’s not just a gut feeling, however, that makes me wary of xenotransplants. Scientists have warned that implanting animal cells into humans carries the risk of introducing a new virus into our species. Think of HIV, Mad Cow Disease, SARS. We’ve got avian flu breathing over our shoulders. Early this year a pig-to-human Ebola case was confirmed in the Philippines. And now here we are in the midst of the swine flu epidemic, which only makes the thought of porcine cells in my body more disturbing.
Elliott has said that the risk of a pig endogenous retrovirus, the virus thought to be most contagious for humans, infecting humans is largely “theoretical.” There is no evidence of a risk of retrovirus infection, he said. And the piglets Elliott uses have been isolated on islands south of New Zealand. They are not known to carry any agent that could infect humans and they are held in a sterile environment.
Elliott has done this before. He ran two previous trials, the first with six patients in New Zealand in 1995-1996. The second, in Russia, began in July 2007 and was comprised of 10 patients.
The cells implanted into one of the volunteers in the 1995-1996 New Zealand study continued producing insulin 12 years after being implanted, which suggests that this procedure can work. The other volunteers either rejected the porcine cells or the implanted cells stopped producing insulin.
Ideally, human, not pig, insulin producing cells would be used for transplants, but there are many obstacles on the road to successful islet cell transplants, and the major problem limiting the therapy is the lack of human donors. It’s way too early to know, but perhaps one day porcine cells will be commonly used to treat diabetes. Maybe they’ll even work better than human cells. Unless researchers find a way to mass produce human islet cells, the porcine ones will certainly be more available. As is often the case in medicine, it’s really a question of the benefits versus the risks. The patients in Elliott’s trial all suffer from a very unstable, severe form of diabetes, but for the most part, diabetics aren’t doomed like a baby with defective heart.