Indeed they have been found in muscle, blood and brain tissue. But researchers have been surprised to discover that a stem cell from one organ can make the cells of another organ if placed in the chemical environment of the second organ. Researchers, for example, showed last year that they could convert human blood stem cells into brain cells. Initial research with fat stem cells suggests that they can be converted into many other types of body tissue, possibly including nerve cells. The possibility that fat stem cells can make all these other tissues may make it less likely that scientists will have to rely on the controversial use of human embryonic or fetal stem cells to usher in the new era of stem cell medicine.
Many people are opposed to using tissue from human embryos or aborted fetuses for research purposes.
Supporters of using human embryonic cells, which are known to be capable of making all the other cells of the body, contend that stopping such research would limit knowledge about what these cells can do for human health. If we are carrying around our own reservoir of stem cells in our fat, then you can make the argument that we shouldn't be using human embryos. A remarkable feature of stem cells is that they can make copies of themselves, as well as spin off cells that can change into the tissue of specific organs. Farshid Guilak, director of orthopedic research at Duke University Medical Center, who first announced the conversion of fat stem cells into cartilage in February, has now implanted converted human cartilage into mice. So far our results show that once the fat stem cells have been converted into cartilage, they stay that way.