The advantage of using embryonic stem cells in cloning research, organ transplantation, and in finding cures for disease, is that these cells are basically “unprogrammed.” This means that the stem cell has not yet determined what it will grow to become so, in theory at least, scientists can manipulate them into becoming anything that they are programmed to be.
Two teams of scientists working independently (Kazutoshi Takahashi and Shinya Yamanaka at Kyoto University, Japan and James Thompson’s team at the University of Wisconsin) announced that they had successfully replicated the biological abilities of the embryonic stem cell using only skin cells. Called “induced pluripotent stem cells” these former skin cells were programmed to become other types of cells, acting in the same way as the embryonic stem cells.
This transformation was accomplished by introducing four basic genes into skin cells, via a viral carrier. These genes cause the adult skin cells to revert and become the equivalent of embryonic stem cells. The breakthrough is in the ability to “unprogram” skin cells so that they revert to cells that have the same response and abilities as embryonic stem cells.
The debate regarding embryonic stem cells has been focused on the harvesting of the cells. A fertilized embryonic egg is allowed to mature until it formed blastocysts. These blastocysts contain the newly formed stem cells. When these stem cells are removed, the embryo is destroyed. If skin cells can be successfully converted to stem cells, this could negate the ethical questions of the use of embryonic stem cells and produce a large amount of readily available stem cells for research.
Caution must be taken with this new technology. For example, one of the genes used to unprogram the skin cells is carcinogenic (cancer-causing).
Research must also be done to verify that these reprogrammed cells don’t have subtle differences between themselves and true embryonic stem cells.
Although the ability to “unprogram” skin cells to form pluripotent stem cells is a significant breakthrough, it is important to stress that this is still a research tool and it will take quite some time before it is known if these cells can truly substitute for stem cells in the treatment of disease.
References:
Kazutoshi T, Tanabe K, Ohnuki M, Narita M, Ichisaka T, Tomoda K, Yamanaka S: Induction of Pluripotent Stem Cells from Adult Human Fibroblasts by Defined Factors: Cell (2007), 131, 1-12.
Kolata G, Scientists Bypass Need for Embryo to Get Stem Cells, New York Times, 2007; A-21:23.
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