STAP cells, glowing green, have been integrated into the mouse fetuss body tissues. Credit: Haruko Obokata

Researchers have observed that plants, when stressed, can reprogram their cells into stem cells, capable of differentiating into many different cell types. Now, it appears mammals can perform the same trick. Japanese scientists say they have successfully reverted blood cells back to their embryonic state after dipping them in a stress-inducing bath of acid.

The team accomplished the feat using blood cells from mouse spleens, but are now trying to replicate it using human blood cells. Independent researchers are praising the discovery for both its simplicity and its potential to usher in new therapies and cloning techniques.

Scientists currently deploy one of two methods to obtain stem cells: extract them from human embryos, or reprogram adult cells into a stem-cell state (called induced pluripotent stem cells, or iPS cells). However, both methods have their drawbacks. Taking cells from an embryo destroys it in the process, and creating iPS cells requires a complicated choreography of genetic modifications.

The new method called STAP, for stimulus-triggered acquisition of pluripotency appears to be far easier. Chris Mason, a professor of regenerative medicine at University College of London, didnt mask his excitement for the BBC:

I thought my God thats a game changer! Its a very exciting, but surprise, finding If this works in people as well as it does in mice, it looks faster, cheaper and possibly safer than other cell reprogramming technologies personalized reprogrammed cell therapies may now be viable.

Haruko Obokata, the studys lead author, conceived of the idea after she noticed blood cells behaved peculiarly after squeezing them through a capillary tube. The cells would shrink to a size resembling stem cells. Intrigued, she replicated the technique by exposing blood cells to different types of stress. Three stressors perforating the cell membrane, exposure to an acidic solution, and physical squeezing caused the cells to behave like stem cells.

However, it was only the first step. Scientists needed to demonstrate that the transformed cells were truly pluripotent or capable of morphing into any type of cell.

To test that, scientists used mice bred to carry a gene that causes a protein in pluripotent cells to glow neon green. They injected the newly created stem cells into mouse embryos and the developing pups glowed all over, indicating that the embryos had successfully incorporated the stem cells into every tissue in their body. The team published their findings Wednesday in Nature.

Stressing blood cells harnesses a natural process, and could streamline the creation of stem cells. Jeff Karp, an associate professor at Brigham & Womens Hospital in Boston, told CNN the new method could produce stem cells up to 10 times faster than current methods.

Follow this link:
New Method of Creating Stem Cells is a "Game Changer"

The development of human embryonic stem cells, which have the ability to form any cell in the body, may enable us to repair tissues damaged by injury or disease. Initially, these cells could only be obtained through methods that some deemed ethically unacceptable, but researchers eventually developed a combination of genes that could reprogram most cells into an embryonic-like state. That worked great for studies, but wasn't going to work for medical uses, since one of the genes involved has been associated with cancer.

Researchers have since been focusing on whittling down the requirements needed for getting a cell to behave like a stem cell. Now, researchers have figured out a radically simplified process: expose the cells to acidic conditions, then put them in conditions that stem cells grow well in. After a week, it's possible to direct these cells into a state that's even more flexible than embryonic stem cells.

The catalyst for this work is rather unusual. The researchers were motivated by something that works in plants: expose individual plant cells to acidic conditions, grow them in hormones that normally direct plant development, and you can get a whole plant back out. But we're talking about plants here, which evolved with multicellularity and with specialized tissues in a lineage that's completely separate from that of animals. So there's absolutely no reason to suspect that animal cells would react in a similar way to acid treatmentand a number of reasons to expect they wouldn't.

And yet the researchers went ahead and tried anyway. And, amazingly, it worked.

The treatments weren't especially harshonly a half-hour in a pH of 5.45.8. Afterward, the cells were placed in the same culture medium that stem cells are grown in. Many of the cells died, and the ones that were left didn't proliferate like stem cells do. But, over the course of a week, the surviving cells began to activate the genes that are normally expressed by stem cells. This was initially tried with precursors to blood cells, but it turned out to work with a huge variety of tissues: brain, skin, muscle, fat, bone marrow, lung, and liver (all of them obtained from micethis hasn't been tried with human cells yet).

While these cells didn't divide like stem cells, they did behave like them. Injecting them into embryos showed that they were incorporated into every tissue in the body, meaning they had the potential to form any cell. That suggests they are a distinct class of cell from the other ones we're aware of (the researchers call them STAP cells).

But, if they don't grow in culture, it's hard to use or study them. So, the authors tried various combinations of hormones and growth factors that stem cells like. One combination got some of the STAP cells to grow, after which they behaved very much like embryonic stem cells. But a second combination of growth factors got the cells to contribute to non-embryonic tissues, like the placenta, as well. So, in this sense, they seem to be even more flexible than embryonic stem cells, and seem more akin to one of the first cells formed after fertilization.

The people behind this development have done a tremendous amount of work, so much that it was spread across two papers. Still, like many good results, it raises lots of other questions. Many cells in our bodies get exposed to acidic conditions every daywhy do those manage to stably maintain their identity? A related question is what goes on at a molecular level inside the cell after acid treatment. Understanding that will help us learn more about the stem cell fate itself.

And then there are the practical questions. How close are these STAP cells to an actual embryonic cell, in terms of the state of its DNA and gene expression? And, if there are differences, are they significant enough to prevent these cells from being used in safe and efficient medical treatments?

January 30, 2014. DOI: 10.1038/nature12968, 10.1038/nature12969 (About DOIs).

See the rest here:
Acid bath turns cells from any tissue into stem cells

Japanese scientists say they have developed a new process to make stem cells that is simpler and faster than current methods. Sarah Toms reports.

EMBRYONIC FORM: A mouse embryo formed with Stimulus-Triggered Acquisition of Pluripotency (STAP) cells.

BREAKTHROUGH: Stimulus-Triggered Acquisition of Pluripotency (STAP) cells.

In experiments that could open a new era in stem cell biology, scientists have found a simple way to change mature animal cells back into an embryonic-like state that allows them to generate many types of tissue.

The research, described as game-changing by experts in the field, suggests human cells could in future be reprogrammed by the same technique, offering a simpler way to replace damaged cells or grow new organs for sick and injured people.

Chris Mason, chair of regenerative medicine bioprocessing at University College London, who was not involved in the work, said its approach in mice was "the most simple, lowest-cost and quickest method" to generate so-called pluripotent cells - able to develop into many different cell types - from mature cells.

"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," he said.

The experiments, reported in two papers in the journal Nature this week, involved scientists from the RIKEN Center for Developmental Biology in Japan and Brigham and Women's Hospital and Harvard Medical School in the United States.

The researchers took skin and blood cells, let them multiply, then subjected them to stress "almost to the point of death", they explained, by exposing them to various events including trauma, low oxygen levels and acidic environments.

One of these "stressful" situations was simply to bathe the cells in a weak acid solution for around 30 minutes.

Read the rest here:
Ordinary cells turned into stem cells 'game-changing'