Reprogramming Stem Cells to Be Cartilage

Working with stem cells derived from fat tissue, researchers have shown that these cells can be converted into cartilage and induced to produce collagen. As cartilage has few blood vessels, nerves and lymphatic support, it has a limited capacity for repair when damaged. This makes it an especially good candidate for replacement by engineered tissue.

The research team, from Duke University (Durham NC, USA), used fat cells left over from liposuction. These were filtered to isolate a colony of cells rich in stem cells. These cells were fed growth factors and cultured in a three-dimensional configuration to simulate the way cartilage cells grow naturally. Fat cells grown in this way began to produce collagen, a main ingredient of cartilage. When these cells were implanted under the skin of mice, they continued for three months to produce collagen and other ingredients in a matrix characteristic of cartilage. These results were reported in the April 2002 issue of Biochemical and Biophysical Research Communications.

"For patients with tissue damage, we envision being able to remove a small piece of fat and then growing customized, three-dimensional pieces of tissue that would then be surgically implanted where needed,” said Dr. Farshid Guilak, director of orthopedic research at Duke.
In a related study, cells were taken from a pad of fat that lies behind the kneecap using a minimally invasive procedure that is less disruptive than liposuction. Three groups of these cells were placed in three different environments and given steroids and growth factors that would encourage the growth of cartilage, bone, and fat. After a period of weeks, the cell cultures were examined. The first group had developed collagen matrix molecules characteristic of cartilage. The second group developed calcium phosphate deposits as if they were beginning to build a structure of bone. The third group began producing fat cells.

These results suggest that it may be possible to reprogram stem cells taken from fatty tissue into a variety of other cell types.



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