|Turned up to eleven: Fair and Balanced|
Wednesday, April 10, 2002
Transterrestrial Musings, a very short comment on the neo-Luddite Bush Admin. approach to cloning has prompted a vociferous response. I have posted several comments there, and will comment at length here. The crux of the argument, started by Orrin Judd, is that cloning is highly unethical for a number of (IMHO bogus) reasons, including the horrific failure rate, and the specious argument that there should be some debates over what rights a clone might have (do you ask this question about identical twins?). The argument finally devolves into a discussion of "organ farming" from anencephalic donors, who would be created by this method. This is in some Kassian way "yuck-inspiring", but I don't really see a moral issue. The anencephalic "person" has no will, and no soul, unless you are a Cartesian Dualist, which brings up its own problems. It is not conscious, and is in no real sense a person. However, setting that issue (its really a religious one) aside, the anencephalic donor is simply impractical. It would be very expensive, time consuming, and difficult to create, bring to term, give birth to, and care for an anencephalic newborn (they are often spontaneously aborted in utero). Maintaining an anencephalic "person" would be incredibly difficult and expensive. The complex hormonal pathways, and neurostimulatory pathways that are necessary for development would be lacking in this "person". Surprisingly (to those without an understanding of developmental biology), this, admittedly most "yuck-inspiring" scenario is also the least likely. This is at best science fiction, and not very good science fiction at that. Of course, we could always outlaw this sort of "organ farming", if we wished, rather than throwing the baby out with the bathwater.
A quick perusal of even the popular literature on organ replacement therapies suggests three options for dealing with organ shortages;
1. Animal organs-these can work, (also called xenotransplantation), but the patient must be immunosuppressed, and chiefly this would serve to stave off death until a human donor was found.
2. Artificial organs-mechanical-like the Abiocor heart, these would do the same as (1), but with lower risk of rejection, although still far too high for permanent replacements (so far)
3. Bio-artificial organs. This is already very far progressed in the case of liver and blood vessel tissues, and is based on the idea that cells, in a dish, given the right signals and "scaffolding" can organize themselves into a functional organ. The reason why this works lies in understanding how complex tissues develop. When tissues form and grow, the cells within the tissue excrete substances which form what is called the Extracellular Matrix (ECM). This matrix of glycoproteins is controlled by complex hormonal interactions by substances known as "growth factors." These are secreted by various cell types at various times, and when detected by their target cells, they trigger complex developmental responses, including the secretion and organization of the ECM. The cells then form a three-dimensional tissue or organ on this scaffolding, much of which is removed after the organ had fully grown. Work done by many scientists (including my wife) has shown that artificial scaffoldings can also be used, and cells in a premature state of development, when placed on these matrices, can develop into the "differentiated" tissue cell types. This has been done with the cornea (my wife worked on this), the liver, and blood vessels. The starting cells are not necessarily stem cells (embryonic or adult), but it is thought that using stem cells would add potency to this technique, perhaps allowing for organs that are not now available to be grown, quite literally, in a dish. In summation, don't brush this notion aside, because it is the most likely (IMHO of course), and would be far and away the most valuable method for organ manufacture. As an aside, for organ donation, adult stem cells would be the preferred starting material, because the adult stem cells could be taken from the patient himself (from the bone marrow), and the resulting organ would not have any chance of rejection. In an embryonic stem cell method, this would be more difficult (I'm not sure, but I don't think we know every cell surface marker involved in tissue rejection). That's all for now, back to my taxes! (ugh!!)