Petri Dish Politics - biomedical revolution

Reason, Dec, 1999 by Ronald Bailey

"What happens when a skin cell turns into a totipotent stem cell [a cell capable of developing into a complete organism] is that a few of its genetic switches are turned on and others turned off," writes University of Melbourne bioethicist Julian Savulescu in the April 1999 issue of the Journal of Medical Ethics. "To say it doesn't have the potential to be a human being until its nucleus is placed in the egg cytoplasm is like saying my car does not have the potential to get me from Melbourne to Sydney unless the key is turned in the ignition." Since nearly every cell in the human body contains the complete genetic code of an individual, it is logically possible using biotech to turn every one of a person's cells into a complete new human being. If one doesn't turn on the ignition of a car (or one doesn't strip the suppressor proteins from a nucleus and put the cell into a womb), then the car won't go (or the skin cell won't grow into a human being). In other words, simply starting a human egg on a particular path, either through fertilization or cloning, is a necessary condition for developing a human being, but it isn't sufficient. A range of other conditions must also be present.

"I cannot see any intrinsic morally significant difference between a mature skin cell, the totipotent stem cell derived from it, and a fertilised egg," writes Savulescu. "They are all cells which could give rise to a person if certain conditions obtained." Those conditions include the availability of a suitable environment like a woman's womb. A petri dish is not enough.

"If all our cells could be persons, then we cannot appeal to the fact that an embryo could be a person to justify the special treatment we give it," concludes Savulescu. "Cloning forces us to abandon the old arguments supporting special treatment for fertilised eggs."

The DNA content of a skin cell, a stem cell, and a fertilized egg are exactly the same. The difference between what they are and what they could become is the environment in which their DNA is found. Thus, Savulescu argues, the mere existence of human DNA in a cell cannot be the source of a relevant moral difference. The differences among these cells are a result of how the genes in each are expressed, and that expression depends largely on which proteins suppress which genes. Does moral relevance really depend on the presence of the appropriate proteins in a cell? Trying to base moral distinctions on this level of biochemistry seems a bit quixotic.

So, asks Savulescu, is it immoral for you to take one of your skin cells, put it into an enucleated egg, and begin to grow it in a petri dish with the intention of making new brain cells to cure your Parkinson's disease? The cell was your tissue, with your genes. The transformed cell would not exist except for your intention - it would simply have flaked off and gone down the drain. "It's important to remember that essentially every cell in our body has a full complement of genes and in that sense is potentially totipotent," Varmus, the NIH director, reminded the National Bioethics Advisory Commission. That a cell contains a complete set of human chromosomes, yours, surely does not make that cell the moral equivalent of a baby. But as Savulescu and Varmus point out, if one is committed to the sort of genetic essentialism relied on by many opponents of cloning and embryonic stem cell research, then one is also logically committed to maintaining that the only difference between your skin cell and your twin is which proteins decorate their DNA strands.