South Korean stem cell pioneer Woo Suk Hwang briefly left a hospital Monday and made a tearful return to work after being treated for extreme stress brought on by an ethics scandal over his groundbreaking research.
By the end of the day, however, Hwang had returned to the hospital for unspecified reasons, said Seoul National University spokesman Lim Jong-pil. He had been hospitalized since Wednesday, and it wasn't immediately known how long he would stay.
The university, where Hwang works, also launched an investigation into the controversy over the veracity of his work.
Hwang, who gained international renown for cloning the world's first human embryos and extracting stem cells from them, hugged students who welcomed him back to his office at the university.
"I am sorry for causing anxiety to the public," Hwang told reporters. He vowed to continue his stem cell research and cooperate with the university's investigation.
Ethical lapses at issue
Hwang is considered a national hero in South Korea for his pioneering research. But the scientist has recently been questioned over ethical lapses.
He publicly apologized last month after admitting that, despite earlier denials, he used eggs donated by two junior female scientists in his lab. He also stepped down as head of the World Stem Cell Hub, an international project launched in October aimed at finding treatments for incurable diseases.
The South Korean Health Ministry cleared Hwang of ethics violations last month, saying the egg donations were voluntary and not coerced. However, U.S. support for his work has waned in the wake of the latest allegations.
Questions about images
In addition, Hwang's work came under question after he said an editing error led to some duplicate images of stem cell colonies being submitted to the journal Science.
The journal's editors have said the mistake doesn't affect the validity of the findings. But South Korean media reports have quoted an unnamed scientist at the University of Pittsburgh, whose scientists previously collaborated with Hwang, alleging the images were deliberately fabricated.
Seoul National University said Monday it would select an expert internal panel to investigate the allegations of fabricated photos. "I think all these controversies are the pain all of us pay to ensure our society, and especially science and technology, enter into (a) mature and advanced society," a spokeswoman said.
On Sunday, Hwang had asked the university to conduct the probe and said he was willing to provide Science with more data from his research to prove its authenticity.
South Korea's Science and Technology Ministry said it wouldn't intervene with the university's probe. It voiced concern, however, the investigation could delay Hwang's research.
"We hope that everything would be cleared up through discussions to establish facts, and normal research activity would be put back on track," Kim Young-sik, director general of the ministry's basic research bureau, told The Associated Press.