Cloning pioneer Woo Suk Hwang apologized Friday for the controversy around his purported breakthroughs in stem cell research but stood by his work, saying it would be authenticated after tests performed within days.
"Our research team made patient-specific embryonic stem cells, and we have the technology to produce them," Hwang told a news conference.
On Thursday, a doctor who provided human eggs for Hwang's research told local broadcasters that Hwang had agreed to withdraw a research paper published by the journal Science in May because the stem cells produced for the internationally acclaimed article were faked. However, Science has said it hasn't received any such notification.
Hwang acknowledged Friday that the cells created for the Science article had all since died after being contaminated, and that efforts to save them failed.
Still, he said other cells were now being unfrozen that would serve to prove the veracity of his work within days.
"I would like to have time to confirm the validity of the technology," Hwang said.
Roh Sung-il, chairman of the board at Mizmedi Hospital, who co-wrote the paper and provided eggs to Hwang, told MBC television Thursday that Hwang had pressured a former scientist at his lab to falsify data to make it look like there were 11 stem cell colonies. Nine of the embryonic stem cell lines Hwang had claimed were cloned in the paper were faked, Roh told KBS television, and the authenticity of the other two was unknown.
Hwang alleged Friday that five of his stem cell colonies had been replaced with those produced by Mizmedi, and he called on law enforcement authorities to investigate how that happened.