Truly Pluripotent Adult Stem Cells

Truly Pluripotent Adult Stem Cells. According to  Chazenbalk’s team, then: in-vitro testing of the cells suggests they may be truly pluripotent–meaning that they could be differentiated into every type (some 200) of human cell in the body, as can be done with both embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs).

Adult stem cells are normally designated multipotent: they can be differentiated into several other of the body’s cell types. But nowhere near as many as ESCs and iPSCs.

If Chazenbalk et al have found truly pluripotent adult stem cells–it will be a major breakthrough, as the derivation of both embryonic and induced pluripotent stem cells is time consuming (to say nothing of the bioethical issues raised by the use of embryos in ESC research).
It’s no surprise that some scientists are skeptical.

Alexey Bersenev, for example, points out on his stem cell blog that while the fact that MUSE cells express many pluripotency markers, similar to embryonic stem cells, marker expression alone is not rigourous enough of a test of pluripotency.

And the differentiation of the stem cells should be carried out in mice, not just in vitro, he urges.
University of California Davis stem cell specialist Paul Knoefpler is also cautious:

One puzzle admitted even by the researchers is that the MUSE cells do not form teratoma, a type of tumor generally readily produced in the laboratory by true pluripotent stem cells. Other purported adult pluripotent stem cells have also failed to make teratoma, raising skepticism, although if these cells were truly pluripotent their lack of teratoma forming activity would be good from a safety perspective.
Another concern is that the MUSE cells may be damaged by the severe stress that they endured including being exposed to large amounts of toxic debris and chemicals released by all their neighboring cells that were essentially nuked by the harsh conditions used in this protocol. Such damage to MUSE cells could include mutations and chromosomal damage; notably in this PLoS One paper the authors did not report looking for such damage (e.g. by karyotyping analysis that examines chromosomal integrity or by more advanced genomics techniques).

Adult stem cells that turn out to be truly pluripotent would represent something of a holy grail, but further testing will need to be done to show the UCLA team has discovered the real thing–and not simply another source of multipoint stem cells.

http://www.forbes.com/sites/johnfarrell/2013/06/08/have-scientists-finally-found-truly-pluripotent-adult-stem-cells/