A Big Fat Hope for Medical Research
Dr. Robert Ersek, a 66-year-old plastic surgeon, invited reporters to his Texas operating room recently and, in front of their cameras, proceeded to liposuction himself.
After numbing the skin near his navel, he slipped in a hollow tube about a quarter of an inch wide and moved it back and forth until it had sucked out about half a pound of fat.
His office throws away tons of liposuctioned fat each year. But he shipped his to a California company for processing and storage of some of the cells.
Why did he do that? It turns out the type of cell being stored for Ersek is medically promising.
Medical value? In fat? The waist product most people want to get rid of?
It’s true. Fat is a little-discussed source of stem cells, versatile biological building blocks that can morph into a variety of tissues. Fat-derived stem cells, researchers say, might someday provide replacement tissue for treating such conditions as Parkinson’s disease, heart attacks, heart failure and bone defects.
“We’re trying to make fat do good,” said Dr. J. Peter Rubin, assistant professor of plastic and reconstructive surgery at the University of Pittsburgh School of Medicine. He’s also president of the fledgling International Fat Applied Technology Society.
The fat-derived cells, being studied by relatively few labs, aren’t the ones that store fat. Instead, they’re found in between fat-storing cells. They’re an example of so-called “adult” stem cells, different from the controversial embryonic stem cells.
When stem cells are taken from an embryo, the embryo is destroyed. That’s abhorrent to people who consider an embryo to be developing human life. President Bush has restricted federal money for research into embryonic stem cells, a step that Democratic presidential nominee John F. Kerry has said he will reverse if elected.
Some who oppose research into embryonic stem cells champion the cause of adult stem cells, found in bone marrow and elsewhere, and theoretically could be taken from the very people who will be treated with them. Scientists have found evidence that adult cells can turn into a variety of cell types.
Fat has “certainly been overlooked as a potential source of stem cells,” said Dr. Adam Katz, a plastic surgeon who studies fat-derived cells at the University of Virginia. Actually, it’s probably the most practical source, he said.
Why?
Fat is plentiful and researchers say it’s easy to harvest -- much easier than marrow, for example. Just about everybody carries enough to yield a good supply of cells for his or her own treatment. Fat produces so many stem cells that there’s no time-consuming need to grow more in the lab. Giving up fat isn’t likely to be medically dangerous. After all, who’d object?
“This is the only stem cell that people will pay you to take out of them,” said Kevin Lee, chairman of the neuroscience department at the University of Virginia.
Though Ersek’s self-liposuction was to publicize the idea of banking one’s own fat-derived cells for future use, researchers say doctors may one day remove fat when the cells are needed.
Research into fat-derived cells is still in early stages and questions remain. Katz says he’s not convinced they deserve to be called stem cells, because he’s not sure they turn into other kinds of cells when transplanted into the body. But he says they do show promise for being used someday to treat disease.
Rubin says there’s good evidence the fat-derived cells can morph into bone, cartilage, skeletal muscle, blood vessel tissue and fat, at least in the laboratory, with possibly can also turn into heart muscle and nerve cells.
Lee says people look askance when he talks about fat-derived cell research, but some studies point to a possible payoff.
* In May, scientists reported such cells could turn to bone and heal defects in the skulls of mice.
* Korean scientists reported last year that when they put human fat-derived cells in the brains of rats that had simulated strokes, the animals showed some improvement.
* Lee found cells will migrate to damaged brain areas in rats and turn into what look like brain cells, but it’s not clear if they hook up with neighbors to form working circuits.
* Dr. Kai Pinkernell, a Tulane University cardiovascular researcher, says he found an encouraging result in pigs given experimental heart attacks. When he took fat-derived cells and put them in hearts of the same pigs, the hearts began to work better.
But how? The standard explanation would be that the cells, sensing that the heart needed new muscle to replace tissue lost in the heart attack, morphed into heart muscle. But Pinkernell said he can’t prove that.
Katz said they could be producing therapeutic effects in other ways. Maybe they’re alerting other stem cells that already live in the target tissue or that show up from the marrow, he said. Or maybe they’re stimulating the growth of new blood vessels that speed up healing.
Marc Hedrick, president of Macropore Biosurgery Inc. of San Diego, which hopes to harness such cells to treat heart attacks, said there’s good evidence the cells can become heart muscle cells. But they probably also stimulate nearby cells to make new blood vessels, heightening the therapeutic effect, he said.
In any case, Rubin figures that fat-derived cells might someday provide a way to grow replacement bone and cartilage to resurface joints damaged by arthritis. They might even be used to make more fat, he said.
Researchers say they need to learn more about what the cells can do and how safe it would be to use them in treatment, especially what long-term risks might be. Attempts to test the cells in humans have been scarce worldwide, but researchers said human studies in the United States might start within five years.
Dr. Curt Civin, a stem cell expert at Johns Hopkins University, called fat-derived cells intriguing but said he had questions of his own: How do they compare with stem cells from elsewhere in the body, like bone marrow? Do they live in fat deposits or are they passing through via the bloodstream? Do they have unique abilities?
“When you really do the cost benefits, do they come out, even if they’re not unique, as superior in some respects?” Civin asked. “The jury is still out.”
“Not a lot of researchers in the world have realized this tissue might be a potential source of these types of cells,” Pinkernell said. “But I think it’s just a matter of time.”
