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 to 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 that is 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 plui-potent 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 know 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.

 

Dr. Bernstein summarizes an article on stem cells that was published in the journal Nature:

This study demonstrates that after wounding the skin of an adult mouse, an embryonic-like change in the epidermal cells outside of the hair follicle stem cells can be induced to form new hair follicle stem cells. In other words, these cells originate from epidermal skin cells in the wound, but then are able take on the characteristics of hair follicle stem cells and actually produce hair. These regenerated hair follicles establish a stem cell population that can produce a hair shaft and continue through all stages of the follicular cycle. The research suggests that these regenerated hair follicles grow new hair through the introduction of Wnt proteins.

The technology, developed at the University of Pennsylvania School of Medicine, has been licensed by Follica Inc. a privately held medical device company.

Reference: “Hair Follicle Regeneration in Adult Mouse Skin After Wounding,” Ito, M., et al. Nature 447, 316-320, May 17, 2007