In a dramatic example of medical recycling, researchers at Duke University reported Tuesday they have been able to "retrain" fat cells removed during liposuction to create functional cartilage.
Not only were the scientists able to transform the cells in the lab, they also grew new cartilage-forming cells on a three-dimensional scaffold, a critical step in being able to repair damaged cartilage in humans.
"This holds out the possibility, some time in the future, of taking fat cells from someone with a cartilage injury and growing new cartilage within a mold to replace damaged tissue," said Geoffrey Erickson, a graduate student in biomedical engineering at Duke University Medical Center who presented the experiment before the annual meeting of the Orthopedic Research Society in San Francisco.
The Duke researchers said it will still take at least three to five years to move their technique into actual medical use.
"For patients with cartilage damage, we envision being able to remove a little bit of fat, and then grow customized, three-dimensional pieces of cartilage which would then be surgically implanted in the joint," said Farshid Guilak, director of orthopedic research at Duke and senior member of the research team.
"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."
The researchers said at this point, they would expect the technique would mainly help people who injure their joints as a result of an accident or sports injury. Patients with osteoarthritis, a disease that causes deterioration of cartilage, would not be good candidates until the cause of the disease can be identified and corrected.
The team used a biochemical cocktail of several different steroids and growth factors to get a specific type of precursor fat cell, called adipose-derived stromal cells, to transform into cartilage cells. Normally, the cells would form the structure of fat deposits in the body.
The researchers compared a group of cells that didn't get the stimulant treatment with those that did, and found that only the treated group looked and acted like normal cartilage cells, producing the proteins and other substances released by that type of cell.
Cartilage is a connective tissue that lines joints throughout the body. But because the tissue is poorly supplied by blood vessels, nerves and the lymphatic system, it has a very poor ability to repair itself when damaged.
"For people who suffer a cartilage-damaging injury, we don't currently have a satisfactory remedy," Guilak said. "There is a real need for a new approach to treating these injuries."
Collaborating with the Duke team was Dr. Jeff Gimble of Artecel Sciences, a Durham. N.C., firm that holds the patent for the process that isolates stromal cells from fat. The research was funded in part by Artecel and the National Institutes of Health.
The loss of cartilage due to injury, degenerative diseases and aging affects as many as 60 million Americans, according to some estimates. Some surgeons have had success with harvesting, growing and re-implanting patients' own cartilage cells in injured knees.
Other researchers have been able to create cartilage cells from undifferentiated stem cells taken from bone marrow. But this type of harvesting is painful and invasive, and has yielded a relatively small number of cells.
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