Hwang Woo-suk. Credit: Chung Sung-Jun/Getty Images
SEOUL -- Hwang Woo-suk defended his work today, saying he did, in fact, create 11 stem cell lines and claiming errors in a paper published in May in the journal Science were due to mismanagement, not fraud. He added that he can prove his ability to create patient-specific stem cells within the next ten days.
"I want to make it clear that we did make the stem cells and we do have the core technologies," he said in a televised news conference. "If I am given the minimum time and support to re-enact the experiment, I'm sure I can achieve it–so that the core technology will not die away."
Hwang admitted that six of his patient-specific stem cell lines were accidentally contaminated by a fungus in January and did not survive. He said he was able to revive two additional stem cell lines, form six additional lines and then form three more lines after the paper was submitted.
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On November 18th, he said, he and his researchers found out these stem cells had been switched with embryonic stem cells against their knowledge. When they tested the cells, they found they were the same as non-patient-specific embryonic stem cells stored at MizMedi Hospital in Seoul. Hwang said he has asked law enforcement authorities for an investigation into the switch.
He also said he is unfreezing five patient-specific lines that were frozen early on in the experiment. Within ten days, he said, researchers will be able to determine whether they came from the donors and are, therefore, patient-specific. He also said he could create more patient-specific cells if given the time and funding.
Despite his claims, Hwang—a national hero in South Korea for being the first to clone a puppy and to extract stem cells from cloned human embryos—said he was withdrawing the paper from Science. He said duplicate photos of the same colony are incorrectly labeled as different lines in the paper, and he apologized for this "human error."
"No matter what the reason, I feel responsible as head researcher for creating this huge controversy," he said. "And I apologize."
Hwang's statement followed a media storm yesterday, when collaborator Roh Sung-il told the press that Hwang had admitted to falsifying data in the Science paper. Earlier this week, US stem cell expert Gerald Schatten of the University of Pittsburgh sent a letter to Science and to the other authors of the paper asking that his coauthor credit be retracted. He also recommended that the paper be withdrawn, citing ethical concerns and allegations he had received that elements of the report may have been falsified.
Before reports of fabrication emerged, Hwang had already faced a month of shame, beginning when he admitted to accepting egg donations from junior researchers, for which he apologized. Hwang was hospitalized for stress shortly after his admission; he returned to his laboratory on Friday morning.