Human pluripotent stem cells without human cloning

Nov 21 2007

Two major scientific papers published this week in Science and Cell unveil a proven way to generate patient-matched human pluripotent stem cells without human cloning, and without the use of human embryos or human or animal eggs.

Research groups in Wisconsin and Japan have generated "induced pluripotent stem" (iPS) cells with the properties of human embryonic stem cells by direct reprogramming of adult cells.

These are the studies which prompted Ian Wilmut, creator of Dolly the sheep and one of the world's leading authorities on the cloning process Somatic Cell Nuclear Transfer (SCNT), to announce that he was abandoning SCNT to focus on reprogramming instead.

The following summary and analysis was produced by Maureen Condic, Ph.D., Associate Professor, Department of Neurobiology and Anatomy, University of Utah School of Medicine and Markus Grompe, M.D., Director, Oregon Stem Cell Center and Professor, Department of Molecular and Medical Genetics Oregon Health Sciences University (affiliations are for reference only). A fuller version of their analysis is available at the Do No Harm: The Coalition of Americans for Research Ethics website at http://www.stemcellresearch.org/statement/pptalkingpointsweb.pdf.

Unlike embryonic stem cells, which are obtained by destroying live embryos, iPSCs are made directly from adult cells by adding a small number of factors to these cells in the laboratory. These factors remodel the mature cells and convert them into stem cells that are functionally identical to stem cells obtained from embryos. No human eggs are required and no human embryos are generated.

Adult cells are obtained from a simple skin biopsy, 1/10th inch in diameter and about as painful as a blood draw. One study was able to produce an average of 10 pluripotent stem cell lines from a single skin biopsy. This approach can be used to generate stem cell lines from patients with specific genetic diseases to better study these conditions, and to provide patient-specific stem cells for possible stem cell therapies.

Direct reprogramming of human cells is one of the most significant scientific findings of the last quarter century; more significant than cloning Dolly the sheep. Indeed, the scientist who originally cloned Dolly, Professor Ian Wilmut, recently stated that direct reprogramming is "extremely exciting and astonishing", a scientific approach he finds "100 times more interesting" than cloning--so much more interesting that he will abandon cloning research and pursue direct reprogramming instead.

The power of direct reprogramming is that, like cloning, it generates stem cells that are genetically identical to the patient who donated the adult cells. Reprogrammed cells would not be rejected by the patient's immune system if used for medical therapies. Unlike human cloning, which has thus far not been accomplished and remains only a theoretical possibility, iPSCs have been generated by two independent laboratories, making patient-specific pluripotent stem cells a reality today. Also unlike cloning, no eggs are needed for the iPS procedure and no human embryos are produced or destroyed, thus resolving major ethical and practical difficulties associated with the cloning procedure. Thus, on both ethical and practical grounds, direct programming is superior to cloning as a means of obtaining patient-specific pluripotent stem cells.