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Thursday, March 11, 2004
Liposuction fat turned into stem cells
By ROWAN HOOPER
In "Fight Club," Brad Pitt's character turns human fat into soap and with beautifully sick panache sells it back to the same rich women who'd paid to have it removed by liposuction. Now scientists at Duke University Medical Center in Durham, N.C., have shown greater ingenuity and made something rather more lucrative from the same leftover liposuction fat: stem cells.
Until now, it was thought that adult stem cells could only be found in bone marrow. But the Duke researchers found that they could take cells from fat and "reprogram" them to grow into bone, cartilage, fat and nerve cells. Who would have thought that something so potentially useful could come from the sagging bottoms and rolling bellies of American fatties?
Kristen Lott, for one. A fourth-year medical student at Duke, Lott recently announced her lab's results at the 50th annual scientific meeting of the Orthopedic Research Society in San Francisco.
"Our findings indicate that 62 percent of human fat cells could be reprogrammed to turn into at least two other different cell types," Lott said. "This percentage of cells is quite high, meaning that they have a great deal of flexibility and that their ultimate destiny may not be so predetermined."
"These results suggest that these cells are truly stem cells that could provide a source of undifferentiated cells for multiple uses," Lott continued. "We're still a long way from using these cells as therapies in humans, but we're excited about the progress we've made so far."
Scientists across the United States will also be excited. Researchers in the States are currently subjected to tougher restrictions on the use of human stem cells than in many other parts of the world, restrictions that many American scientists feel will give other countries the edge in developing new procedures.
Stem cells can replicate themselves and generate different cell types. They are found in all stages of development, from embryo to adult, but crucially, those produced at the embryo stage have the potential to develop into any of the 200 different cells types: Researchers call these "totipotent" stem cells. Those derived from fat are not so flexible, and are termed "multipotent" stem cells.
They are so valued because they offer the chance to regenerate damaged or diseased organs. Those suffering from Alzheimer's, diabetes and spinal injury could benefit, which is why Christopher Reeve, paralyzed from the neck down, is so keen on stem-cell research.
And because the stem cells would be taken from the patient who requires the treatment, there is no danger of immune-system rejection. To make them, the nucleus of a cell from the patient is transferred into an egg cell that has had its own nucleus removed. The cell is then made to start dividing as if it were a normal fertilized egg.
Stem cells can be harvested from the embryo, which is then destroyed, usually while it is still only a tiny ball of 150 or so cells. (In the U.K., stem-cell research can only be conducted on embryos before Day 14 of development. This is sometimes called therapeutic cloning. Reproductive cloning, on the other hand, would allow the embryo to develop and be implanted into a woman with the aim of creating a cloned baby. Most governments support the former and strongly reject the latter type of cloning.
But U.S. President George W. Bush would like to stop all forms of cloning using human embryos, and in 2001 he restricted National Institutes of Health funding to a limited number of existing stem-cell lines. Bush, who identifies himself as a born-again Christian, has a moral objection to destroying embryos. Incidentally, Sen. John Kerry, the Democratic presidential nominee, says he would permit therapeutic cloning while banning baby-making reproductive cloning.
Farshid Guilak, director of orthopedic research and senior member of the Duke team, anticipates that the first patients set to benefit from the team's research are those who have suffered some sort of cartilage damage due to injury or trauma. And he looks forward to a time when entire joints ravaged by osteoarthritis can be relined with bioengineered cartilage.
"We don't currently have a satisfactory remedy for people who suffer a cartilage-damaging injury," Guilak said. "There is a real need for a new approach to treating these injuries. We envision being able to remove a little bit of fat, and then grow customized, three-dimensional pieces of cartilage that would be surgically implanted in the joint. One of the beauties of this system is that since the cells are from the same patients, there are no worries of adverse immune responses or disease transmission."
Rowan Hooper is a researcher at Trinity College Dublin. He welcomes comments at firstname.lastname@example.org A book of a selection of these columns translated into Japanese, "Nou to sekkusu no seibutsugaku (Evolution, Sex and the Brain)," is published by Shinchosha.