Stimulus-triggered acquisition of pluripotency cell
Stimulus-triggered acquisition of pluripotency cells (also known as STAP cells) are a type of pluripotent stem cell that can be generated by subjecting ordinary cells to certain types of stress, such as the application of a bacterial toxin, submersion in a weak acid, or physical squeezing.
In the original research presenting the technique, STAP cells were produced by bathing differentiated T cells in an acid bath with a pH of 5.7 for half an hour. Following this treatment, the cells were verified to be pluripotent via observing the presence of Oct-4, a transcription factor expressed in embryonic stem cells, using green fluorescent protein. On average, 25% of cells survive the stress, and 30% of those that survive convert to pluripotent cells. Squeezing the cells had an effect toward pluripotentcy, but with lower efficiency. STAP cells injected into mouse embryos grew into a variety of tissue and organs found throughout the body. According to the researchers, the mice "[appeared] to be healthy, fertile, and normal" after one-to-two years of observation.
STAP cells are able to differentiate into placental cells, meaning they are more potent than embryonic stem cells or induced pluripotent stem cells (iPS). It is not clear why such ordinary cells do not convert into stem cells when subjected to similar stimuli under ordinary conditions, such as acidity in the body. It is hypothesized that the reaction is somehow blocked when the cells are within a body. Work is underway to generate stimulus-triggered acquisition of pluripotency (STAP) cells using human tissue, but no results are available as of February 2014.
The technique for producing STAP cells was developed by Haruko Obokata at the Brigham and Women's Hospital (BWH), while she was studying under Charles Vacanti, and then at the RIKEN Center for Developmental Biology in Japan. The finding was spawned by a chance observation of Obokata. In 2008, while working at Harvard Medical School, she noticed that some of the cultured cells she was working with shrank to the size of stem cells after being squeezed through a capillary tube. She went on to test the effects of various stimuli on cells. After perfecting her technique, Obokata was able to show that white blood cells from newborn mice could be transformed into cells that behaved much like stem cells. She repeated the experiment with other cell types including brain, skin, and muscle cells with the same result.
Initially Obakata's findings were met with skepticism, even among her coworkers. "Everyone said it was an artefact – there were some really hard days", she recalled. The manuscript describing the work was rejected multiple times before its eventual publication in the journal Nature. A series of experiments, first turning a mouse embryo green by fluorescently tagging STAP cells, then video taping the transformation of T-cells into pluripotent cells, finally convinced skeptics that the results were real.
Compared to the existing iPS techniques, stimulus-triggered pluripotency cells could be generated more easily and efficiently, though the method has only been demonstrated as effective in mouse cells. If the findings can be duplicated in human tissue, it could lead to cheap and simple procedures to create patient-specific stem cells. Stem-cell researcher Dusko Ilic of King's College London called STAP cells "a major scientific discovery that will be opening a new era in stem-cell biology". Shinya Yamanaka, a pioneer of iPS research, called the findings "important to understand nuclear reprogramming ... [and] a new approach to generate iPS-like cells". The fact that STAP cells can form placental tissue could make the use of the cells considerably easier by bypassing the need for a donor egg and in vitro cultivation.
Previously, stem cells have been created by the controversial technique of cloning embryos, or via genetic manipulation of adult cells into iPS cells. Progress on iPS-based therapies has been slow due to regulatory hurdles surrounding genetic manipulation. Additionally, iPS techniques have an observed efficiency of around 1%, significantly lower than the observed efficiency of STAP.
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 Cyranoski, David (2014-01-29). "Acid bath offers easy path to stem cells". Nature News (Nature Publishing Group). Retrieved 2014-01-30.
- ↑ Gallagher, James (2014-01-29). "Stem cell 'major discovery' claimed". BBC News. Retrieved 2014-01-31.
- ↑ NHS Choices (2014-01-30). "Breakthrough in stem cell creation using acid bath - What did the research involve?". nhs.co.uk. Retrieved 2014-02-06. "They put them in a weak acid solution (pH 5.7) for 30 minutes at 37°C, and then put them into petri dishes and grew them at normal pH."
- ↑ Thomson, Helen (2014-01-29). "Stem cell power unleashed after 30 minute dip in acid". New Scientist. Retrieved 2014-01-31.
- ↑ 5.0 5.1 5.2 5.3 5.4 5.5 5.6 Sample, Ian (2014-01-29). "Simple way to make stem cells in half an hour hailed as major discovery". The Guardian. Retrieved 2014-01-31.
- ↑ Grens, Kerry (29 January 2014). "New Method for Reprogramming Cells". The Scientist.
- ↑ "STAP cell pioneer nearly gave up on her research". The Asahi Shimbun. 30 January 2014. Archived from the original on 30 January 2014.
- Stress turns ordinary cells pluripotent News release at RIKEN with videos.