The debate over which form of stem cells will be most beneficial for clinical applications is far from over, and there may well never be a clear “winner.” The true winners will be the patients who will benefit from whichever method proves most feasible, cost effective, broadly accessible, and acceptable to regulatory agencies—whatever cell-based therapies can deliver the cures needed regardless of the source of the cells.

“It is still early days” in the clinical testing of pluripotent stem cell-derived therapies; all three types of pluripotent stem cells will be around for a while, and the debate will continue, says Paul Knoepfler, Ph.D., associate professor at UC Davis School of Medicine. Dr. Knoepfler received the 2013 National Advocacy Award from the Genetics Policy Institute, organizer of the World Stem Cell Summit 2013, taking place in San Diego. The award recognizes his ongoing advocacy for stem cell research, including his blog ( and new book Stem Cells: An Insider’s Guide.

Ethical, socioeconomic, safety, manufacturing, complexity, and purity/characterization issues still swirl around the various stem cell types moving into clinical studies: traditional embryonic stem cells (ESCs) derived from discarded IVF materials; induced pluripotent stem cells (iPSCs); and somatic cell nuclear transfer (SCNT)-derived ESCs (NT-ESCs).

Each has its pluses and minuses. iPSCs offer a portal to personalized medicine, are “easier and cheaper” to make, “but may have [more] genomic glitches,” says Dr. Knoepfler, as shown during a session he chaired at the summit. Whether these genomic alterations, such as copy number variations (CNVs) and changes in DNA methylation patterns, are meaningful is not yet clear, however.

“Cloned ES cells are a tough technology and only a handful of labs in the world can do it,” says Dr. Knoepfler. Recent evidence that a stimulant such as caffeine can enhance the process may change the trajectory of this approach, making it difficult to predict where this field might be in five years’ time. The conventional route to ESC development from IVF embryos is more affordable and faster, but both ESC technologies carry an ethical burden.

For more from the World Stem Cell Summit, be sure to check out “Neural Precursors ‘Cure MS’ in Mice“, “Mary Ann Liebert Wins Stem Cell Education Award“, “$1M Award to Develop a Replacement Liver Announced“, “Stem Cell Leaders Call for Human Embryome Project“, “World Stem Cell Summit: December 6, 2013 Update“, and “World Stem Cell Summit: December 4, 2013 Update“.

Also, watch our video “A Brief History of Stem Cells” to see a timeline spanning over 60 years of stem cell research. 

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