Fat Can Be - Stem Cell Source!

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-inch wide and moved it back and forth until it had sucked out about half a pound of fat.

Ersek's office throws away tons of liposuctioned fat every year. But he shipped his own to a California company for processing and long-term storage of some of the cells from that fat.

Why did he do that? It turns out the type of cell being stored for Ersek is medically promising. In fact, an international group of scientists is meeting Monday and Tuesday in Pittsburgh to discuss its potential.

Medical value? In fat? The waist product most people want to get rid of?

It's true. As members of the fledgling International Fat Applied Technology Society will discuss at their meeting, fat is a little-discussed source of stem cells, those 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," says IFATS president Dr. J. Peter Rubin, assistant professor of plastic and reconstructive surgery at the University of Pittsburgh School of Medicine.

The fat-derived cells, which are 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 Kerry has said he will reverse if elected.

Some who oppose research into embryonic stem cells champion the cause of adult stem cells, which are found in bone marrow and elsewhere and theoretically could be taken from the very people who will be treated with them. In recent years, scientists have found evidence that adult cells can turn into a wide variety of cell types.

While such studies have focused largely on cells from marrow, fat has "certainly been overlooked as a potential source of stem cells," says Dr. Adam Katz, a plastic surgeon who studies the 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, even slender people, carries enough to yield a good supply of cells for their own treatment. Fat produces so many stem cells that there's no time-consuming need to grow more of them in the lab. Giving up some fat isn't likely to be medically dangerous. And after all, who'd object?

"This is the only stem cell that people will pay you to take out of them," says Kevin Lee, chair of the neuroscience department at the University of Virginia.

While Ersek's self-liposuction was meant to publicize the idea of banking one's own fat-derived cells for future use, researchers say doctors may one day remove fat right when the cells are needed.

To be sure, the research into fat-derived cells is still in very early stages and many questions remain. Katz, in fact, says he's not even convinced the cells deserve to be called stem cells, because he's not sure they really do turn into other kinds of cells when transplanted into the body. Nonetheless, 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 suggestive evidence they can also turn into heart muscle and nerve cells.

Lee says people look at him askance when he talks about research into fat-derived cells, but some studies point to a possible payoff.

-Last May, scientists reported that 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 has found the cells will migrate to damaged brain areas in rats and turn into what looks like brain cells, though it's not clear yet whether the cells hook up with neighbors to form working circuits.

-Dr. Kai Pinkernell, a cardiovascular researcher at Tulane University, says he found an encouraging result in pigs that were given experimental heart attacks. When he took fat-derived cells from the pigs and put them into the hearts of the same donor animals, those hearts began to work better.

In fact, they worked just as well as hearts that received stem cells from marrow, the gold standard for this kind of experiment, he said.

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. He also says he's more interested in the results than the explanation.

Katz, the skeptic about whether such cells really change identities, 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.

Dr. 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.

"They're like orchestra leaders, we think, in terms of healing," Hedrick said. "They not only participate by playing an instrument, but they also direct some of the other people in the orchestra."

In any case, Rubin figures fat-derived cells might also 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, for uses like breast reconstruction after surgery, he said.

Researchers say they need to learn much more about just what the cells can do and how safe it would be to use them in treatment, especially what the 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 in Baltimore, called the fat-derived cells intriguing but said he had some questions of his own: How do they compare with stem cells from elsewhere in the body, like bone marrow? Do they really live in fat deposits or are they just passing through via the bloodstream? Apart from their abundant supply, do they have any 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."

Pinkernell, for one, is optimistic about finding a medical value in fat.

"Not a lot of researchers in the world have realized this tissue might be a potential source of these types of cells," he said. "But I think it's just a matter of time."