In 2002, President George W. Bush authorized funding for human embryonic stem cells (hESCs) using federal money for the first time - but he limited that federal funding to existing lines.
His political opponents latched onto his decision and declared that he "banned" hESCs and that he was an enemy of science, a fabrication which dogged him in the overwhelmingly Democratic-voting science community. In 2009, President Barack Obama used an executive order to slightly modify the lines federal money could fund, and his political supporters declared he "lifted the ban" on hESCs. Meanwhile, the president refused to lift the actual ban on using federal funding for somatic cell nuclear transfer in humans, despite calls from biologists to understand the science and not let hysteria determine policy.
But the Obama administration's ongoing distrust of science has repercussions. Another study has found that SCNT is much better and more accurate at reprogramming human skin cells to become embryonic stem cells, capable of transforming into any cell type in the body, without epigenetic abnormalities that plague other methods.
Writing in Nature (SCNT is government funded in the UK and the Nature publisher is a British subsidiary of a German media conglomerate), the authors affirm what scientists in America have long said; for stem cell therapies to advance, scientists need for the administration to get out of the way. Stem cell therapies hold the promise of replacing human cells damaged through injury or illness, meaning embryonic stem cells could someday treat or cure Parkinson's disease, multiple sclerosis, spinal cord injuries and many other diseases and conditions.
Shoukhrat Mitalipov, Ph.D., director of
Oregon Health & Science University's Center for Embryonic Cell and Gene Therapy, made a breakthrough in May 2013 when they successfully used somatic cell nuclear transfer to convert human skin cells into embryonic stem cells. In 2007, Mitalipov's team successfully transformed monkey skin cells into embryonic stem cells.
The somatic cell nuclear transfer process Mitalipov and his team use involves transplanting the nucleus of one cell, containing an individual's DNA, into an egg cell that has had its genetic material removed. The unfertilized egg then develops and eventually produces stem cells.
Since 2006, however, many scientists have been focused on a different process to convert adult somatic cells — for instance, skin cells — into something very much like embryonic stem cells. The process happens through the introduction of four specific genes into the adult cell and produces transformed cells called induced pluripotent stem cells — or iPS cells. These cells, like embryonic stem cells, are capable of transforming into any type of cell in the body. The iPS process was pioneered by Japanese scientist Shinya Yamaka in 2006, who shared the 2012 Nobel Prize for his work.
Since Yamaka's discovery, however, it's been known that iPS cells do not match exactly to genuine embryonic stem cells. That could affect how they can be used in stem cell research or therapies.
The current research is the first to more deeply compare the somatic cell nuclear transfer and iPS methods — and to analyze how the SCNT and iPS methods worked when they each started with the same set of skin cells.
The study found that stem cells produced from the skin cells by the SCNT method were almost identical to embryonic stem cells produced through in vitro fertilized eggs — which are considered the "gold standard." The iPS cells made from the same skin cells, in contrast, retained a large number of the skin cells' characteristics, referred to as "memory."
"We think the difference is remarkable," Mitalipov said. "The SCNT method faithfully erases the memory of the skin cell and converts it into an embryonic stem cell. The iPS method produces a cell with significant differences and abnormalities."
"If you believe that gene expression is important, which we do, then the closer you get to the gene expression patterns of embryonic stem cells, the better," said co-author Joseph R. Ecker, Ph.D., professor and director of Salk's Genomic Analysis Laboratory and co-director of The Center of Excellence for Stem Cell Genomics. "Right now, nuclear transfer cells look closer to the embryonic stem cells than do the iPS cells."
"If we can figure out how the egg manages to do a better job at reprogramming compared to the iPS method, it may help us develop a better iPS method," says co-author Louise C. Laurent, assistant professor in the Department of Reproductive Medicine at the University of California, San Diego.
Until then, Mitalipov said, he believes the SCNT method is a much better candidate for cell replacement therapies. "And we hope science can continue to develop stem cell therapies — so that somebody they can help us battle and defeat diseases that are defeating us today."