Riken's Haruko Obokata has resigned after efforts to replicate her approach for reprogramming cells to an embryonic-like state failed.
In now-retracted papers published in Nature nearly a year ago, Obokata and her colleagues claimed to be able revert differentiated cells to a pluripotent state by exposing them to a strong stimulus like low pH, a phenomenon dubbed stimulus-triggered acquisition of pluripotency, or STAP. Critics soon began to point out inconsistencies in images in the papers and questioned the methodology; a number of labs said they couldn't repeat the findings.
Riken also launched an investigation, which identified instances of fabrication and falsification, and found Obokata guilty of research misconduct. Its independent team also could not replicate the STAP approach, though continued to try different cells under various conditions.
Those efforts, even with Obokata's subsequent help, Riken now says have failed, ScienceInsider reports.
"Dr. Obokata has been unable to reproduce the … phenomenon," Shinichi Aizawa, who was leading the Riken verification team, said during a press conference according to the Wall Street Journal. "While we initially planned to continue efforts until March, we will end the experiments at this point."
In the wake of this announcement, Obokata has resigned. In a statement, Obokata says that she is "very puzzled by these results."
ScienceInsider notes that there are still "a number of lingering questions" regarding this case, including why none of Obokata's co-authors tested the approach in their labs and why the papers were accepted by Nature after being rejected by Science and Cell, and receiving unfavorable reviews from Nature's own reviewers.