Picking Up the Pieces After Hwang

A year ago, it seemed so easy. In May 2005, Woo Suk Hwang and his colleagues told the world that they could make embryonic stem (ES) cells from cloned human embryos with an efficiency that astounded--and thrilled--their colleagues. In roughly one out of every 12 tries, the South Korean team reported, they could produce ES cell lines that were a genetic match to patients. Scientists hoped to use such cells to probe the genetic triggers of diseases such as diabetes and amyotrophic lateral sclerosis (ALS). Some dreamed of using them as the raw material for developing new tissues and cells that could treat previously incurable maladies.

A few months ago, those claims famously unraveled. It is now clear that Hwang's team does not have any ES cell lines created from patients. It is also clear that the group didn't fail for lack of trying: The team apparently used more than 2200 donated human oocytes in their experiments--more than five times the number they claimed in their papers (Science, 10 February, p. 754). The meltdown dashed the hopes of researchers and...