Animal-human hybrids going nowhere – just as we predicted

When ‘Cloning & Stem Cells’ (Editor Prof Ian Wilmut) (1) and ‘Nature’ (2) both publish articles suggesting that animal eggs are not suitable to produce human stem cells, as has happened this week, most of the media decides it must be true.

When CORE made similar statements almost a year ago in its submission to the Courts during Judicial Review proceedings against the HFEA, it is hard to believe that anybody even bothered to assess our arguments.

What a joy this week to shout loud and clear, ‘We told you so!’

Some intimation of a change of direction came last month when the Medical Research Council turned down funding applications for the two existing animal-human cloning licences, but we never imagined that the tide would turn so quickly.

We have always argued that animal-human hybrid research was a dead end, and that pragmatic science would prove us right, even if we were not able to convince the UK with our intrinsic ethical objections.

To prove our point, here are some excerpts from an expert witness statement from Prof James Sherley, signed on April 3, 2008, as part of our Court submissions, contesting the licences issued by the HFEA:

‘The applicants’ suggestion that human-animal cloned embryos and derived ESCs will somehow cure themselves of animal mitochondria and animal mitochondria genomes is unsupported. In fact, the well-known phenomenon of mitochondrial heteroplasmy argues against this assertion. In my opinion, animal mitochondria components will persist in human-animal cloned cells and might even be selectively maintained! To my knowledge, de novo synthesis of mitochondria (i.e., not forming from an existing intact mitochondrion) has not been described. Therefore, the larger number of mitochondria in animal eggs is not only likely to persist, but may even predominate.’

‘Even with adjunctive immune-suppressing treatments, cloned hESCs could never provide effective therapies for two reasons. First, they will contain debilitating DNA reprogramming defects known to occur in all cloned animal embryos and ESCs. Second, even hESCs produced from in vitro fertilization (IVF) human embryos would, a priori, be unable to provide cellular functions that are obligatory for repair and maintenance of the organs of children and adults. (Sherley, 2004, J. Biomedicine Biotechnology 2, 71-72; Sherley, 2008, Cell Proliferation, 41 [Suppl. 1] 57-64)’

‘ … there is an even more obvious flaw in human-animal cloning research itself that makes approval of the licenses untenable. … In order for an embryo to function, grow, and develop normally, its complete genome must be unpackaged and read accurately and precisely as it simultaneously progressively increases its cell number and changes its form. Many crucial unpacking and reading factors are found in the part of the animal egg used for making human-animal cloned embryos; and these are unable to correctly unpack and read a foreign genome from another species, like humans. So, a human-animal cloned zygote, right from the beginning and throughout all later developmental stages, will necessarily be unnaturally aberrant.’

‘It is already well appreciated that even when cloned animal embryos are produced with a nucleus and egg of the same species (i.e., therapeutic cloning or somatic cell nuclear transplantation), the unpacking and reading are aberrant. This well-known and well-described problem accounts for the low efficiency of cloning in all species tested so far (including recently reported cloned ESCs from monkeys; Byrne et al. 2007 Nature, 450, 497-502, 22 Nov, 2007) and for the now well-recognized defects and deficiencies in cloned animals.’

‘These problems will be magnified in human-animal cloned embryos (and human-animal cloned ESCs, if it even proves possible to derive them), precluding any relevance of this research to human-human cloning research.’

‘ … cloned interspecies embryos will be intrinsically flawed and, therefore, will not provide relevant or useful information, let alone the cures suggested by scientists seeking licensure for these studies. There is a glaring problem, based on fundamental principles of cellular and molecular biology, which indicates that human-animal cloned embryos can never match up to this justification.’

Prof Sherley got it right; CORE got it right; and the rest of the world is catching up.



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