For the first time, human skin cells have been transformed into embryonic stem cells (eSC). Researchers at Oregon Health & Science University and the Oregon National Primate Research Center (ONPRC) created several lines of SC, which can then become any other cell type in the body and have great potential in regenerative medicine.
This very significant finding was published this week in the journal Cell
. It is possible the entire field of stem cell research shared an immediate flashback to 2005, when Korean scientist Hwang Woo-suk made the exact same claim, only to be discredited for faking his results. The Oregon work may really be a breakthrough. It has simultaneously reignited prospects for patient-derived personalized medicine, as well as worries about renegade scientists creating human clones.
This cloning story was widely noted in the science press. The Los Angeles Times
had good coverage, as did Scientific American
Shoukhrat Mitalipov, lead author and a senior scientist at ONPRC, said this in a press release:
A thorough examination of the stem cells derived through this technique demonstrated their ability to convert just like normal embryonic stem cells, into several different cell types, including nerve cells, liver cells and heart cells. Furthermore, because these reprogrammed cells can be generated with nuclear genetic material from a patient, there is no concern of transplant rejection….While there is much work to be done in developing safe and effective stem cell treatments, we believe this is a significant step forward in developing the cells that could be used in regenerative medicine.
Mitalipov and his group used what is called somatic cell nuclear transfer (SCNT) to change a skin cell to a stem cell. Basically, the nucleus of a skin cell (containing the genetic DNA blueprint) is implanted into an unfertilized egg cell that has had its genetic material removed. The egg cell now has a skin cell nucleus; it reprograms the skin cell and begins to divide, thus producing undifferentiated blastocysts that have the same properties as embryonic stem cells – without the need to use embryos.
SCNT does not entirely escape the ethical tightrope – it is how Dolly the sheep was cloned. Some say it’s only a matter of time before primates, then humans, are replicated. Mitalipov and others point out the technical difficulties of making a primate clone (they have been trying for years to do so), and join mainstream science in opposing any such effort toward human self-reproduction.
Indeed, Mitalipov got started with primaes. His group published a paper in 2007 showing that SCNT worked to make eSC lines from monkey skin cells. The long gap between the primate model and human cell cloning was partly technical, but mostly, said Mitalipov, due to regulatory issues.
Mitalipov’s team carefully navigated the politics of cloning. They also figured out ways to tweak the nuclear transfer process. They used an inactivated virus to unite the egg and body cells, along with electric jolts to jumpstart cell division. Early attempts produced a handful of blastocysts but no stable cell lines. So they added caffeine, which, counterintuitively, slows the process of egg activation.
Dr. George Daley, a Harvard stem cell scientist, told the Scientist:
I think it is a beautiful piece of work… This group has become remarkably proficient at a very technically demanding procedure and [has] shown that SCNT-ESCs may in fact be a practical source of cells for regenerative medicine.
Daley and other stem cell experts think cloned stem cells may have advantages over reprogrammed cell lines (so-called induced pluripontent stem cells, IPSC). Unlike iPSC, cloned cell lines have no “epigenetic memory” and are therefore in a more pure state. Here is a paper
from the National Institutes of Health, Daley as lead author, detailing the possible advantages of SCNT over iPSC.
Human clones? The Oregon researchers downplayed the notion that this research might somehow lead to the creation of humans.
"While the method might be considered a technique for cloning stem cells, commonly called therapeutic cloning, the same method would not likely be successful in producing human clones otherwise known as reproductive cloning," OHSU said in a press release. Attempts over many years to create monkey clones have failed, the university noted, and human cells are even more fragile and less amenable to cloning.
"Our research is directed toward generating stem cells for use in future treatments to combat disease," Mitalipov said. "While nuclear transfer breakthroughs often lead to a public discussion about the ethics of human cloning, this is not our focus, nor do we believe our findings might be used by others to advance the possibility of human reproductive cloning."
Cardinal Sean P. O’Malley of Boston, is far from comfortable with Mitalipov’s work. In a statement, he claims the Oregon work created and destroyed more than 120 human embryos -- human life that must be protected.
Creating new human lives in the laboratory solely to destroy them is an abuse denounced even by many who do not share the Catholic Church’s convictions on human life. This means of making embryos for research will be taken up by those who want to produce cloned children as ‘copies’ of other people. Whether used for one purpose or the other, human cloning treats human beings as products, manufactured to order to suit other people’s wishes.
The controversy won’t go away. Neither will Hwang Woo-suk -- he’s is still a cloner. Last year he claimed success in cloning of a coyote. Lately, he reportedly has a deal with Russia’s North-Eastern Federal University to clone a mammoth, the giant elephant that has been extinct for a few thousand years.