Acid bath converts blood cells to stem cells

Stem cells have been created from mouse blood cells using a simple and quick method described as 'remarkable' by experts.

The study identifies a new type of stem cell that is formed under specific stress conditions and has the ability to become all cell types, including placental tissue.

These 'stimulus-triggered acquisition of pluripotency' (STAP) cells were created after cells from week-old mouse pups were bathed in weak acid for half an hour: a result that surprised the scientists, from the Riken Center for Developmental Biology, Japan.

Dr Haruko Obokata, lead author, said: 'A big part of the discovery process was in trying to work out a better explanation for what at the time was an unexplainable observation'.

Obokata and colleagues sampled blood from the spleens of mice that carried a gene only present in stem cells, called Oct-4. These mice had a fluorescent marker attached to the Oct-4 gene so that their cells would glow when Oct-4 was expressed. They found that some white blood cells exposed to acid stress (pH of 5.7, similar to that of Coca-Cola) for 30 minutes would not die as they had anticipated, but would grow. After two days some of these cells began to glow, indicating that they had become stem cells.

With this positive result, the team then injected the STAP cells into mouse embryos, and found that over time the STAP cells were incorporated into all three germ layers of a developing embryo. The pups of these mice also incorporated STAP cells into their tissues, showing that they were inheritable.

STAP cells could be used in stem cell therapy in the future to 'seed' damaged organs with healthy cells, decreasing the need for organ replacement.

Chris Mason, professor of regenerative medicine at University College London, commented on the study: 'If it works in man, this could be the game changer that ultimately makes a wide range of cell therapies available using the patient's own cells as starting material — the age of personalised medicine would have finally arrived'.

The study is published in Nature.

Update: the papers have now been retracted by Nature (see BioNews 761).