Rossi said it was a happy coincidence that using RNA instead of changing the DNA was as much as 100-fold more efficient. He said the effect was possibly because the process more closely reflects how cells themselves transform.
Rossi successfully differentiated his stem cells into muscle cells using RNA, a process that may offer promise in gene therapy and other treatments. His method does not alter the cell’s underlying genome, though Rossi admits that he does not yet understand what it does to the cell’s epigenome, which controls expression of genes.
Rossi said that his cells, which he’s named RiPS, for “RNA induced Pluripotent Stem” cells, are more like embryonic stem cells than traditional iPS cells because they have not been genetically altered.
Melton said the Harvard Stem Cell Institute, which includes several hundred stem-cell researchers from across Harvard University and its affiliated hospitals, will now be making its standard iPS cells with Rossi’s method.
In a prepared statement, Yamanaka, now at the University of California, San Francisco, said Rossi’s approach to generating stem cells seems promising, and he would like to have someone in his lab try it.
“The quality of the induced pluripotent stem cells generated by this method should be carefully examined because their characteristics vary depending on the induction methods and the origins of the resulting cells,” he said. “The standard method to generate iPSCs for clinical applications has yet to be established. I think this method has the potential for it.”
Jacob Hanna, a postdoctoral fellow at the Whitehead Institute for Biomedical Research in Cambridge, said he’s also eager to begin working with the cells.
“I think it’s a very exciting paper with a very promising method,” said Hanna, who was not involved in the research. When asked if he was jealous that Rossi had developed the method first, Hanna said, “Yes, of course! It’s a very nice paper,” quickly adding, “Jealous in a very positive and supporting way.”