New method for growing stem cells

Excerpted from “Acid bath offers easy path to stem cells,” Nature. January 29, 2014 — In 2006, Japanese researchers reported¹ a technique for creating cells that have the embryonic ability to turn into almost any cell type in the mammalian body — the now-famous induced pluripotent stem (iPS) cells. In papers published this week in Nature², ³, another Japanese team says that it has come up with a surprisingly simple method — exposure to stress, including a low pH — that can make cells that are even more malleable than iPS cells, and do it faster and more efficiently.

“It’s amazing. I would have never thought external stress could have this effect,” says Yoshiki Sasai, a stem-cell researcher at the RIKEN Center for Developmental Biology in Kobe, Japan, and a co-author of the latest studies. It took Haruko Obokata, a young stem-cell biologist at the same centre, five years to develop the method and persuade Sasai and others that it works.

Obokata says that the idea that stressing cells might make them pluripotent came to her when she was culturing cells and noticed that some, after being squeezed through a capillary tube, would shrink to a size similar to that of stem cells. She decided to try applying different kinds of stress, including heat, starvation and a high-calcium environment. Three stressors — a bacterial toxin that perforates the cell membrane, exposure to low pH and physical squeezing — were each able to coax the cells to show markers of pluripotency.

Obokata has already reprogrammed a dozen cell types, including those from the brain, skin, lung and liver, hinting that the method will work with most, if not all, cell types. She now wants to use these results to examine how reprogramming in the body is related to the activity of stem cells. Obokata is also trying to make the method work with cells from adult mice and humans. “The findings are important to understand nuclear reprogramming,” says Shinya Yamanaka, who pioneered iPS cell research. “From a practical point of view toward clinical applications, I see this as a new approach to generate iPS-like cells.”

Commentary

CMDA Member and Senior Fellow for Family Research Council David Prentice, PhD: “Stress a Cell, Get a Stem Cell. It seems every time one turns around there’s a new non-embryonic stem cell discovery, each more amazing than the last. The latest in the journal Nature is no exception: simply stressing normal adult cells can transform them into embryonic-like stem cells, similar to the Nobel prize-winning induced pluripotent stem (iPS) cells made by Dr. Yamanaka. But unlike Yamanaka’s technique, these ‘STAP’ cells transform from mature mouse cells into stem cells under the influence of stressors such as acid or stretching, without genetic manipulation and in a much shorter time period. And don’t be confused by some of the stories, including the Nature news report. These are not adult stem cells as found in body tissues, nor are these new stem cells inherently embryos or able to form embryos, despite the fact that these mouse STAP stem cells can form placental as well as body tissue types. It takes more than haphazard production of all tissues to form an organism, as has already been seen with human embryonic stem cells. Dr. Maureen Condic has produced an in-depth review of the range of stem cell potency.

This new technique shows once again that there are many acceptable, ethical routes to stem cells, and absolutely no necessity for life destroying embryo research. Adult stem cells from tissues, which are the gold standard for patient treatment, as well as iPS cells and STAP cells, emphasize that ethical, life preserving science is also the best science.

Resources
CMDA Ethics Statement on Stem Cell Research
Scientific Demagoguery in the Stem Cell Wars by David Stevens, MD, MA (Ethics)