Tearfully accepting the 'mistakes' in her research, a young female scientist who was accused for fabricating data also insisted that her conclusions were accurate.
Haruko Obokata, 30, blamed her youth and inexperience for errors in her methodology, but said she had managed to create the building-block cells capable of growing into the specialised cells of the brain, liver, heart or kidneys.
"I apologise with my whole heart to my co-authors... and many others for causing trouble because of my insufficient efforts, ill-preparedness and unskilfulness," a visibly shaken Obokata told a press conference.
Obokata was feted as a modern-day Marie Curie after unveiling research that showed a simple way to re-programme adult cells to become a kind of stem cell.
So-called Stimulus-Triggered Acquisition of Pluripotency (STAP) cells were hailed as a breakthrough that could provide a ready supply of the base material for much-needed transplant tissue at minimal cost.
Campaigners said it represented a leap forward in the fight against degenerative diseases.
Her profile -- a young woman in a world dominated by middle-aged men -- was seized on by Japan's media, which was charmed by eccentricities that included her insistence on wearing a housewife's apron in the laboratory, instead of a white coat.
But within weeks of her paper being published in the prestigious journal Nature, questions began to emerge, with fellow scientists saying they were unable to replicate her results.
The respected Riken Institute, which sponsored the study, launched an inquiry and declared last week that the study was flawed.
This "amounts to phoney research or fabrication" by Obokata, Shunsuke Ishii, head of Riken's probe committee, told a press conference.
The institute said this week it was launching a year-long study to establish if there was any truth in Obokata's findings.
On Wednesday the young scientist choked back sobs during a two-and-a-half-hour press conference carried on at least two channels, in which she insisted: "STAP cells do exist. I successfully made STAP cells at least 200 times."
She said she did not believe her study should be retracted and said she hoped to announce new research showing "a certain recipe" to create the cells.
"If there is any future for an inexperienced person like me as a researcher, I want to keep working towards the development of STAP cells to a level that could be helpful to someone," she said.