Two new papers have just been published documenting further advances with induced pluripotent stem cells—-stem cells that are “embryonic-like” but that are not derived from embryos. When the announcement was made about the successful attempts at creating induced pluripotent stem cells from adult cells in humans, I wrote an article for the Weekly Standard about how this discovering would mark ” The End of the Stem Cell Wars .” These most recent papers confirm that induced pluripotent stem cells should allow peace for all parties—-in fact, it appears that these cells are proving to be superior to embryonic stem cells in certain respects. One of the initial worries about the method, however, was that the viral vectors used to introduce the transcription factors that reprogram the adult cells to a pluripotent state might cause cancer. But one of the just-released papers, authored by Dr. Shinya Yamanaka—the researcher behind the previous ipsc discoveries—notes that the cancer risk can be overcome.
Here’s a summary of the Yamanaka results:
In this latest study, published in the Feb. 14 issue of Science, the Japanese researchers prove these stem cells are made from normal mature adult cells, and they show that these stem cells can be implanted using a retrovirus without fear of causing cancer.“This is a real nice follow-up and confirmation of the previous papers that looked at inducing normal cells to become stem cells,” said Dr. Hugh Taylor, an associate professor at Yale University School of Medicine.
“The question that still existed from the previous paper was whether these stem cells were some sort of adult stem cells,” Taylor said. “This paper shows that these stem cells are fully differentiated adult cells, that they can be reprogrammed into stem cells,” he added. “You can probably take almost any adult cell and turn it into a stem cell.”
In addition, there has been a fear that using a retrovirus to implant stem cells results in an increased risk of cancer. This study showed that doesn’t happen, Taylor said. “It proves, without a doubt, that these cells are safe for human use,” he noted.
However, Taylor thinks the cells need to be studied over a longer period to ensure they don’t have an elevated cancer risk.
“It will still take years of basic research before we become able to use iPS cells to treat patients,” said lead researcher Dr. Shinya Yamanaka, from Kyoto University in Japan. “We are doing our best to bring it to clinics as quick as possible.”
Here is the paper .
The second paper, from a team of researchers at Harvard, does some important background work in the reprograming methodology. Science Daily summarizes :
Harvard Stem Cell Institute (HSCI) and Massachusetts General Hospital (MGH) researchers have taken a major step toward eventually being able to reprogram adult cells to an embryonic stem cell-like state without the use of viruses or cancer-causing genes.In a paper released online today by the journal Cell Stem Cell, Konrad Hochedlinger and colleagues report that they have discovered how long adult cells need to be exposed to reprogramming factors before they convert to an embryonic-like state, and have “defined the sequence of events that occur during reprogramming.”
The full paper is here .
