Riken announced Friday that it will halt any further attempts to replicate the supposedly ground-breaking stem cell production method one of its researchers claimed to have discovered earlier this year.

The technique, dubbed stimulus-triggered acquisition of pluripotency (STAP), garnered international attention after two research papers on the subject were published in the prestigious journal Nature last January before being retracted months later.

Riken also said Friday it had accepted a resignation letter dated Dec. 21 from Haruko Obokata, the discredited 31-year-old scientist who was the lead author of the papers.

The papers in question claimed to outline a simple but revolutionary way to generate stem cells, which are capable of developing into any type of tissue.

However, falsified data and other fabrication attempts emerged that led the state-backed research institute to set up a team in April to verify the findings. The team was headed by fellow Riken researcher Hitoshi Niwa, who co-authored the papers.

In July, Obokata agreed to retract the papers and began her own experiments at Riken with a third party present to replicate her work using genetically manipulated spleen cells of mice that glow green if a gene indicative of pluripotency is activated.

Riken said Obokata conducted the experiments nearly 50 times and managed to create green-glowing cells, but only at a rate considered very low, meaning the experiments failed, a Riken spokesman said at a press conference in Tokyo.

The spokesman said that after the institute learned of the failure at the end of November, it decided to end the verification attempts, which were originally scheduled to last until next March. The Riken team made a preliminary announcement in August that it had not yet succeeded in replicating the research results.

Niwa admitted that having had no doubt about the data might have been the problem in the first place, but said that he “believed” in the data released by Obokata and co-author Teruhiko Wakayama of Yamanashi University, and that he had faith in science being based on “belief in the inherent goodness of men.”

Obokata was not present at the press conference but she released a statement on Friday saying that she “regrets” the result of the verification experiments.

Obokata said she had to conduct the experiments in an environment that had “far more constraints” than she ever imagined. Obokata was confined in a room to do the experiments and was constantly monitored by camera.

She said she was making a desperate effort to gain satisfactory results under whatever conditions were provided, and that she tried her best, “beyond the limits of the soul.”

“I’m just totally shattered and very perplexed by the results,” she said.

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