... recently, scientists have started to raise concerns about iPS cells.

Last year, a group led by Dr. Robert Lanza, chief scientific officer of Advanced Cell Technology, compared batches of iPS cells to embryonic stem cells and noticed the iPS cells died more quickly and were much less capable of growing and expanding.

"It was the first study showing there were problems. No one wanted to believe it," Lanza said in a telephone interview



n July, Daley's team reported more problems in the journal Nature, showing that iPS cells retain a bit of memory of their prior life as adult tissue, which could limit their use.

And earlier this month, an international team led by researchers at the University of California San Diego found genetic mutations in 22 iPS cell lines taken from seven different labs.

http://www.reuters.com/article/2011/...72U7DL20110331