Human embryo photo: Dr David Becker, Wellcome Images
Earlier this week, the Berlin wall of stem cell research came crashing down.
Yamanaka and colleagues published a report showing that they could obtain cells exhibiting all the qualities of human embryonic stem cells from adult human skin cells. This raises the possibility that human stem cells could be isolated in a way that avoids the ethical concerns regarding use of early human embryos.
The work was an extension of findings the group published in 2006 which showed that, by manipulating four transcription factors (Oct3/4, Sox2, Klf4 and c-Myc), it was possible to “de-differentiate” adult mouse skin cells into stem-like cells that were capable of developing into a variety of tissue lineages and even producing a new mouse.
There was considerable debate following the publication of the mouse work as to whether the same approach would work in humans. The paper, “Induction of Pluripotent Stem Cells from Adult Human Fibroblasts by Defined Factors,” published in the November 30 edition of the journal Cell, seems to put those concerns to rest.
The Yamanaka group has shown that the skin-derived stem cells have all the markers of an embryonic stem cell, can develop into cells of all three germ layers including neural and cardiac cell types and could form teratomas when implanted into mice.
These cells will undoubtedly become a major research tool for studying cellular development and fate control mechanisms. However, it is still too early to claim that the cells will become the basis for treating practically every disease under the sun (as many media reports have breathlessly claimed).
In order to be therapeutically useful it will be necessary to induce “stem-ness” without the use of retroviruses and also to find a way to control the frequent development of cancers that is seen when the cells are given to a recipient.
Despite these caveats, the work of the Yamanaka group in mice and humans is revolutionary and represents a major leap forward in our understanding of cell biology.
Download the paper: “Induction of Pluripotent Stem Cells from Adult Human Fibroblasts by Defined Factors“
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