Human cloning “breakthrough?”

 

Last week, Joe Gibes commented on the BBC’s report on the scientific “breakthrough” of  Dieter Egli and his colleagues at the New York Stem Cell Laboratory. As the BBC and other news agencies presented it, Egli et al derived human embryonic stem cells through a “cloning” technique, but as Joe correctly noted, no clones were produced. In transferring the nucleus of an adult skin cell to a nucleated human egg and retaining both sets of DNA during subsequent embryonic development, the researchers had actually  created not clones but  genomic hybrids with, I would add, a generally lethal defect (triploidy).

I see nothing sinister behind the imprecise language, and I don’t think Joe does either. It is, in fact, understandable as the method employed was essentially a modification of the technique (“somatic cell nuclear transfer”) that Ian Wilmut and his colleagues at the Roslin Institute used 15 years ago to create “Dolly” the sheep, the world’s first clone of an adult mammal. The chief difference is that Wilmut et al transferred the donor nucleus to an enucleated egg.

Cloning adult mammals is, to put it gently, no piece of cake. In their ground-breaking publication that introduced Dolly to the world, Wilmut et al reported making 434 attempts to fuse a nucleated donor cell  to an enucleated egg. That effort yielded 277 (63.8%)  zygotes (“fused couplets”) which they then transferred to ligated sheep oviducts for culture. Of those 277,  247 (89.2%) were recovered and of those, only 29 (11.7%) developed to a transferable stage (morula/balstocyst). As a fraction of the original 434 eggs, that represents 6.7%. Now, 14 years after the initial report of Wilmut et al, the process of producing clones from adult mammalian cells remains highly inefficient.

The “Holy Grail” of cloning, as Joe and others have put it, is not a cute little lamb, but a human embryo. Most researchers in the field recoil at the idea of cloning to reproduce full-sized copies of ourselves, but they salivate at the prospect of creating disposable, embryonic miniatures whose genomic identity would purportedly constitute for their “parents” the key to great medical benefit. Human biology, however, has proven quite resistant  to such designs, and that, I would submit, is the “story behind the story” of Egli et al. The whole reason these researchers moved to the hybrid model was because of their inability, and that of many others before them, to produce an embryonic human clone using techniques that, albeit with great inefficiency, have proven successful in animals.[1] What the BBC and others tout as a “breakthrough” is, in fact, little more than an affirmation of the status quo in human cloning research.

Whether human biology will continue to frustrate the dogged efforts of Egli and others to produce a human clone, only time will tell. But at this stage, reality certainly mirrors fiction as the quest for the “Grail” remains exactly that – a quest. Sadly, this quest to clone ourselves exacts a great toll as it drains finite resources and, more concernedly, does great violence to human dignity with its reduction of human life to an object of mere utility.  That we would dump the quest and focus our health resources elsewhere seems a right and sensible thing to do, but I’m not banking on that happening soon as many a policy-maker and researcher are “all-in”  in the gamble on so-called “therapeutic” cloning. That researchers have already discovered a method for re-programming adult human cells to a pluripotent state that requires neither a human egg donor nor an embryonic intermediate reveals the ongoing quest to produce a human clone to be less about advancing good science and medical therapy and more about satisfying a prior agenda.


[1] Sheep (1997), Mouse (1998), Gaur (2000), Pig (2000), Mouflon Sheep (2001), Cat (2002), Cow (2002), Goat (2002), Rabbit (2002), Deer (2003), Horse (2003), Mule (2003), Rat (2003), Wildcat (2003), Dog (2005), Banteng (2005), Ferret (2006), Swamp Buffalo (2006), Gray Wolf (2007).  See the US Food and Drug Administration online publication “Technology Overview: Somatic Cell Nuclear Transfer and Other Assisted Reproductive Technologies” at http://www.fda.gov/animalveterinary/safetyhealth/animalcloning/ucm124765.htm

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Ronald Tarter

Human cloning is going to occur with or without the consent of the public or the government. The issues propelling cloning forward will prove to be overwhelmingly personal, powerful and compelling – bone marrow transplantation for a sick child, interneuronal stem stell transplantation to reverse the stroke damage incurred by a spouse or premature infant, etc.. The advent of repairative cloning technology will be followed by overpowering demand, and as the new cloning subsector of human medicine matures and becomes accepted the actual cloning of human beings will simply slide in through the door, lost in the shuffle. We need… Read more »