• Kyodo


The new type of stem cell developed by Japan’s state-backed Riken institute and Harvard University is a scientific breakthrough that shows we can use a simple method to reprogram mature body cells into an immature state similar to cells in a fertilized egg.

The team’s study on “stimulus-triggered acquisition of pluripotency,” or STAP, was carefully reviewed before publication in the British science journal Nature. The findings are likely to have a significant impact on the field of biology, as well as on medicine and cancer research.

In experiments, the scientists soaked lymph corpuscles taken from 7-day-old mice into mildly acidic liquids for about 30 minutes. The few cells that survived were then cultured and transplanted into mice, where they developed into nerve and muscle tissue.

Researchers of regenerative medicine trying to revive organs and tissues that have been damaged or lost due to injuries or diseases have pinned high hopes on versatile stem cells, which have the power to develop into any type of cell.

Embryonic stem cells, which were the first stem cells to be discovered, required the destruction of fertilized eggs, raising ethical concerns.

A newer method was developed by Nobel Prize-winning Japanese scientist Shinya Yamanaka of Kyoto University to create what he calls induced pluripotent stem cells, or iPS cells, which do not use fertilized eggs. But the method faces the challenge of potentially causing cancer as the production process involves injecting genes into the cells.

The STAP cells are a third way. They simply require exposing body cells to acidic liquids for cultivating, without destroying embryos or manipulating genes. The Riken team says no abnormalities have been found in chromosomes.

One of the co-authors of the paper is Yoshiki Sasai, deputy director of the Riken Center for Developmental Biology. He said he initially wondered “if such a thing would be possible.”

The referees of the U.K. journal apparently had the same doubt.

It has been known that plant cells return to an immature state in response to changes in the environment. However, it was considered impossible that animal cells that had survived a harsh environment — in this case, acidic liquids — would revert to an immature state.

The paper’s lead author, Haruko Obokata, a scientist at the Riken center, conducted further experiments during the nine months before the paper was chosen for publication following its submission to Nature last March. For days, she took pictures of cell movements and performed genetic analysis to prepare for questions from referees.

If scientists can produce the same result with human cells in the future, the STAP method may offer a promising avenue for disease research and regenerative medicine.

“There is no reason that what you can do with iPS cells cannot be done with STAP cells,” Sasai said.

But competition for producing stem cells using the STAP method is expected to be “incredibly tough worldwide,” Sasai said. He said the next couple of years would be decisive, adding he is personally rooting for Obokata to develop her research.

The paper says that acidic liquids rejuvenate cells by causing stress to them. There may be more than one method to cause cell rejuvenation as cells have been known to change their nature after surviving different types of stress, such as pressure and toxins.

If scientists further refine the technique to change the nature of cells, they may pave the way for using cell stress as medicine and repairing damaged organs inside the body of patients.

Obokata doubts the technique can be quickly applied to advanced studies, saying it is still only being tested on mice. But she also expressed hopes for new possibilities, such as its application in cancer research.

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