Ethicists and pro-life opponents of embryonic stem cell (ESC) research say that the rapidly advancing science has demolished the arguments of those justifying sourcing cells from embryos. The debate, they say, is over.
ESC advocates disagree, insisting that embryonic cells remain the “gold standard” in stem cell research.
The biggest challenge yet to ESC research emerged in November 2007, when scientists in Japan and the U.S. reported that ordinary human skin cells can be reprogrammed into a new kind of cell – an induced pluripotent stem (iPS) cell – that shares an ESC’s potential to develop into other types of cell such as blood, brain and muscle.
The discovery, which built on earlier pioneering work on mice by Japanese Prof. Shinya Yamanaka, was revolutionary, calling into question the need to obtain embryos – whether donated after IVF treatment, or cloned in a laboratory – and to destroy them.
Furthermore, iPS cells genetically match the donor whose skin cells were originally used, reducing the risk of rejection by the patient’s immune system – something that could occur if the cells came from a source such as a donated embryo.
But the iPS breakthrough had a downside: The reprogramming process involved the use of genetically engineered viruses, which scientists worried could mutate and cause tumors in tissues grown from the iPS cells.
This week, however, new research reported in the journal Nature revealed that scientists had managed to produce iPS cells without using viruses. An Edinburgh-based team from Britain and Canada reprogrammed skin cells by inserting four genes, which were removed once the process was complete, leaving no trace of the genetic modification.
“It is a step towards the practical use of reprogrammed cells in medicine, perhaps even eliminating the need for human embryos as a source of stem cells,” said the study leader, Dr. Keisuke Kaji of the University of Edinburgh’s Center for Regenerative Medicine.
The new development – the creation of cells brimming with the therapeutic potential of ESCs but without the ethical controversy or safety concerns – comes at a time when the U.S. scientific community is anticipating a lifting of restrictions of federal funding for ESC research, imposed by President Bush in 2001.
‘Don’t abandon ESCs’
The breakthrough is being welcomed by those on both sides of the debate over embryonic research, with ESC opponents say it further strengthens the argument that embryos are redundant in stem cell research.
Dr. David van Gend, national director of Australians for Ethical Stem Cell Research, called the advance “beautiful.”
“We can now create the equivalent of embryonic stem cells from our own body cells, without ever using women’s eggs or cloning a human embryo – and that removes all the ethical concern from this magnificent field of medical research.”
“This is ethical stem cell research we can all agree on,” said Josephine Quintavalle of the British organization Comment on Reproductive Ethics. “Embryonic-type cells have been derived successfully and safely from adult tissue without involving human embryos. This is very good news and takes much of the battle out of the stem cell debate.”
But ESC proponents are unconvinced.
“It will take years to thoroughly compare these [iPS] cells to ‘gold standard’ human embryonic stem cells to see if they are biologically and medically equivalent,” Rick Weiss, a senior fellow at the liberal Center for American Progress, wrote on the organization’s Science Progress site.
Weiss predicted that ESC research opponents would “jump on the findings as an excuse to argue that President Obama need not keep his campaign promise to loosen the federal funding restrictions.”
“Virtually all scientists agree that the smart way to unleash the promise of embryonic stem cells and regenerative medicine is to pursue multiple lines of work using cells produced by a variety of techniques under strict ethics guidelines, and see which ones prove most valuable in the end for various purposes,” he said. “The Obama administration must not waver in its commitment to this sensible approach.”
The Financial Times in an editorial also urged politicians to reject ESC research opponents’ “arguments that the latest developments are a reason to abandon embryonic stem cells.”
“The discovery of iPS cells was based firmly on work with human embryos, and every scientist in the field insists that its future depends on continuing to work on embryonic stem cells,” it said.
Ian Wilmut, head of the Center for Regenerative Medicine, where the study was done, agreed that embryonic work must continue for now. But he also conceded, in a radio interview, that “in a few years’ time” there will no longer be any need to use cells from embryo, and the ethical debate will “slowly fade away.”
Wilmut, a longtime proponent of cloning human embryos for their stem cells, is best known for his role in creating the world’s first cloned mammal, Dolly the sheep.
‘Yesterday’s redundant science’
The new development was reported just days after U.S. Senators Arlen Specter (R-Pa.) and Tom Harkin (D-Iowa) introduced legislation aimed at freeing up federal funding for research on unwanted IVF embryos. The Stem Cell Research Enhancement Act is virtually identical to earlier legislation passed by Congress and twice vetoed by Bush.
Although Obama has pledged to rescind Bush’s 2001 policy by executive order, Specter said legislative change was important, to ensure that the issue “does not ping-pong back and forth with each successive president.”
In Australia, parliaments in the six states are working on legislation that will bring them into line with a 2006 federal law that lifted a ban on the cloning of early-stage human embryos for stem cells.
Lawmakers in South Australia state are voting this week, and Australians for Ethical Stem Cell Research has written to each member to draw their attention to the new research findings.
The association said, “There could be no more timely scientific breakthrough than this, to confirm for you that creating and destroying cloned embryos for stem cells is yesterday’s redundant science: that while embryo-cloning might have been supported in good faith in the pre-iPS era, its unique justification no longer exists.”
Last May, lawmakers in another state, Western Australia, threw out equivalent legislation, after opponents argued that the unfolding iPS cell developments had made cloning for stem cells unnecessary.
The remaining four states passed their comparative legislation during 2007 – before the November 2007 iPS cell breakthrough.
Van Gend said that if Australia’s federal parliament had known in 2006 what was known today about iPS cells, “no cloning legislation would have seen the light of day.”