Embattled scientist Haruko Obokata has failed to produce her so-called STAP cells in experiments at Riken, officials at the research institute and other sources said Thursday, casting further doubt on her claims.
Obokata, a Riken researcher, was the lead author of a pair of papers that claimed to have discovered a new and simpler way to produce pluripotent stem cells, which are capable of developing into any type of tissue, through a process dubbed stimulus-triggered acquisition of pluripotency, or STAP.
Obokata and her team were lauded after their papers on the purported STAP discovery appeared in the prestigious journal Nature earlier this year. The papers were eventually retracted due to allegations of misconduct, and Riken has been trying to verify Obokata’s findings ever since.
The state-backed institute, which said it might halt its attempts to verify Obokata’s method, plans to hold a press conference in Tokyo Friday to announce the results of its verification efforts. Obokata is not expected to attend.
Obokata was allowed to join Riken’s efforts in July under monitoring by a third party. She tried to replicate her own study using genetically manipulated mouse spleen cells that glow green if a gene indicative of pluripotency is activated.
In the course of the experiments, Obokata sometimes succeeded in creating the glowing cells, but only at a very low rate, the sources said. She repeatedly attempted to produce a mouse, a feat which would have illustrated the cells’ pluripotency, by injecting them into the fertilized eggs of another mouse but failed.
A Riken team conducting the experiments said in an interim report in August that it had yet to reproduce STAP cells following the steps outlined in Obokata’s papers, which involved subjecting mouse cells to mildly acidic liquid.
The papers were initially seen as trailblazing when they appeared in the British journal in January. But inconsistencies in them quickly led to allegations of data falsification and fabrication, leading to their retraction in July.
To prevent further misconduct, Riken has revised internal rules to require all staff to receive education on research ethics and stipulate procedures for recording data, Riken sources said.