inhibitory mechanisms may block conversion to pluripotency. Research is underway to generate stimulus-triggered acquisition of pluripotency (STAP) cells using human tissue: in February 2014, Charles Vacanti and Koji Kojima (Harvard researchers originally involved in the discovery and publication of STAP) claimed to have preliminary results of STAP cells generated from human fibroblasts, but concomitantly cautioned that these preliminary results require further analysis and validation. History In the early 2000s, Charles Vacanti and Martin Vacanti conducted studies that led them to the idea that stem cells—spore-like cells—could be spontaneously recovered from ordinary tissues that are stressed via mechanical injury or increased acidity. The technique for producing STAP cells was subsequently studied by Obokata at the Brigham and Women's Hospital (BWH), while she was studying as a post doc under Charles Vacanti, and then at the RIKEN Center for Developmental Biology in Japan. In 2008, while working at Harvard Medical School, she verified at the request of Charles Vacanti that some of the cultured cells she was working with shrank to the size of stem cells after being mechanically injured in a capillary tube. She went on as directed, to test the effects of various stimuli on cells. After modifying the 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 Obokata'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 as an article (together with a shorter jointly-written "letter") within the journal Nature. A series of experiments, first turning a mouse embryo green by fluorescently tagging STAP cells, then videotaping the transformation of T-cells into pluripotent cells, finally convinced skeptics that the results were real. Investigation into disputed claims In the months after the two Nature papers were released, all scientists who tried to duplicate Obokata's results failed and suspicion arose that her results were due to error or fraud. An investigation into alleged irregularities was launched by RIKEN on February 15, 2014. The allegations questioned the use of seemingly duplicated images in the papers, and reported failure to reproduce her results in other prominent stem-cell laboratories. Nature also announced