Scientists generally agree that all cloned animals are biologically flawed. But they don’t agree about what that means for stem cells derived from cloned embryos, the basis for therapeutic cloning.Also known as somatic cell nuclear transfer, therapeutic cloning is a promising approach to create individually customized cellular therapies for treating certain disorders. Demonstrated in mice but not in humans, it begins with stem cells derived from a cloned embryo. But if cloned embryos can’t produce normal organisms, how can they produce normal stem cells? Analyzing the complete gene-expression profiles of both cloned and fertilization-derived stem cells in mice, scientists at Whitehead Institute for Biomedical Research now have concluded that the two are, in fact, indistinguishable.
