On Monday the National Institutes of Health released their final guidelines detailing what types of human embryonic stem cell research will qualify for federal funding. Although the rules permit federal funding of research on embryonic stem cell lines produced from excess early embryos from in vitro fertilization clinics, they disallow federal support of two key techniques used to derive embryonic stem cells in animals: that of transferring the genetic material from one cell into an egg without a nucleus, and that of stimulating an unfertilized egg to divide.
"In terms of extending the classical embryonic stem cell lines that can be used with federal funding, this is an important step forward," said Stanford University School of Medicine stem cell researcher Irving Weissman, MD. "However, the policy banning funding of other stem cell lines produced by transferring the genetic material from a patient to an egg is a terrible disappointment. It seems inconsistent with the president's promise to allow scientific facts to determine science policy." On March 9, President Barack Obama made a statement about his administration’s approach to science policy, in which he vowed to ensure "that scientific data is never distorted or concealed to serve a political agenda, and that we make scientific decisions based on facts, not ideology."
The nuclear transfer process, also known as SCNT or "therapeutic cloning," has been used to derive embryonic stem cells in many animal species. Recent successes in non-human primates, such as monkeys, suggest that researchers will eventually be able to duplicate the feat in humans. However, the rules bar federal funding of research on any human cell lines derived in such a manner, even if their derivation was consistent with all medical ethical considerations.
"They could have said that they would evaluate these stem cell lines when and if they are derived to determine whether they met the appropriate ethical standards," said Weissman, who directs Stanford's Stem Cell Biology and Regenerative Medicine Institute. "Instead, their only justification for not funding research on these lines was that SCNT didn't have public support."
Many who oppose human embryonic stem cell research point to recent advances in another technique called induced pluripotency that "reprograms" adult cells to look and act like their embryonic counterparts. Focusing on these so-called iPS cells, they argue, circumvents any ethical qualms about the use of human embryos. Although such research is important and has been replicated at Stanford and elsewhere, Weissman said, iPS cells can cause cancer in mice if any of the genes used to reprogram the cells remain active.
In contrast, SCNT has been shown in mice to generate stem cell lines that reliably reproduce the genetics of the donor. Furthermore, when SCNT-derived cell lines bearing disease-causing mutations are introduced into developing mice, the recipient animals themselves develop the disease-a proof of principle that has not yet been shown with iPS cells.
In fact, organizations like the International Society for Stem Cell Research, of which Weissman is president, had urged the NIH to allow federal funding for research on both iPS and on SCNT-derived human embryonic stem cell lines. "The NIH is gambling that iPS cells will be functionally equivalent to human embryonic stem cells," said Weissman. "But we don't yet know if diseases like juvenile diabetes, cancer or Lou Gehrig's disease can be recapitulated in this manner."
Source: Stanford Medicine News
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