POSTED 31 MAY 2007
Remember Dolly, the Scottish sheep who said "Ewe, Two"? Ten years ago, this wooly charmer -- the first mammal clone -- put cloning on the scientific and ethical maps. Produced from the union of a gene-free egg with the bare nucleus of an adult cell, Dolly gamboled across the front pages, attracting notice from the tabloids and just about everybody else.
She history's first identical twin based on an adult mammal.
Photo: Courtesy UW-Foundation.
Long before Dolly's somewhat premature death, embryonic stem cells joined cloning as emblems of a brave new reproductive future.
In bioethics, the epochs date BD and AD: Before Dolly, and After Dolly. Before Dolly, the idea of making a carbon copy of yourself was science fiction or Brave New World. AD, that is theoretically possible (although nobody has yet grown a human clone, as far as we know).
Clone: to make an exact genetic copy -- an identical twin.
After Dolly, society has had to confront the merits of limits on scientific advances. Is more knowledge always a good thing, or are certain scientific pathways best unexplored?
Here's another question: Do clones inspire clowns? In 1998, a Chicago physicist named Richard Seed (of all names!) announced plans to produce the first human clone before disappearing from the headlines. In 2002, a bizarre sect of spaceship-worshipping Raelians claimed that "Baby Eve," the clone, had already been born. She never showed her carbon-copy face.
These scary headlines, even more than the curious crowd who crowed about commencing cloning, raised big questions among scientists, ethicists, and just about everybody else: Even if it proves possible to clone humans for reproduction, is it wise, ethical and safe? Does such cloning amount to playing God?
Beyond reproductive cloning, what about "therapeutic cloning," making a carbon copy of an embryo solely as a source of embryonic stem cells? Because these cells can grow into any body cell, therapeutic cloning might lead to genetically matched spare parts that do not trigger an immune response. But people who believe that life begins at conception condemn research on embryonic stem cells as murder, because the embryo is destroyed when the cells are extracted.
Reproductive cloning: to use cloning to make a new animal.
Ten years AD, cloning discoveries continue to produce surprising scientific results that raise ethical, political and scientific questions. Here are some tidbits we gleaned from a talk by Ian Wilmut, of the Scottish Center for Regenerative Medicine and the Roslin Institute. Wilmut led Dolly's cloning, and remains active in the field.
Researchers are using reproductive cloning to genetically change pigs so their organs would escape immune attack after transplant into humans. The idea is to ease the shortage of transplant organs, and reduce deaths on transplant waiting lists. In one test, a pig heart transplanted into a baboon lasted 179 days; normally, the immune system would immediately destroy such a transplant. BTW, Wilmut says the baboon retained its original-equipment heart, and thus survived the experiment.
Cloned animals can be used to create human antibodies. These small, specific molecules are "currently used for many different human clinical applications; including treatment of infectious disease, cancer, transplanted organ rejection, autoimmune diseases and for use as antitoxins," wrote James Robl of Hematech. This firm is working on genetically educating cows to make human antibodies (see #1 in the bibliography) in their milk. Cow's mammary glands are good at making proteins, and the idea is to genetically change the animals to make desirable, high-price proteins for medical purposes. "This was a very strong potential use for our technology," says Wilmut. "This could not be done in any other way."
Meat from cloned cows could soon appear on your dinner plate. The Food and Drug Administration has indicated incipient approval of clone-chops and clone-burgers, and the European Food Safety Authority is probing the safety issue.
Cloning is already being used to "breed" better "bucking bulls" for the rodeo trade.
Photo: ALS Association
Cloning could be used to study diseases caused by unknown genes. Wilmut points to ALS (Lou Gehrig's disease), an invariably fatal destroyer of motor nerves. About 10 percent of cases are inherited through mutations that are largely unknown. The research plan, he says, is to create cell lines with these mysterious mutations, "and study them anyway you can with modern techniques, to look for the difference between normal and sick cells. ... The aim is to have a system where you can test new drugs to find something you can give to the patient to stop the degeneration. This would be a huge advance."
Photo: San Diego Zoo
Cloning could be used to help restore endangered species. In 2003, researchers cloned two Java bantengs, an endangered bovine from Southeast Asia. One of the animals was grossly deformed and put down, but the other is on display at the San Diego Zoo.
Did we forget to mention that a Kentucky fertility-clinic operator told us that he's already implanted five cloned human embryos into women? None became pregnant. Trust us, we'll return to Panos Zavos.
Therapeutic cloning: to use cloning to create stem cells to cure disease. The cells are usually genetically matched to the patient.
Photo: Roslin Institute
In case you've pulled a Rip Van Winkle for the past 10 years, here's our 50-word cloning recipe.
1. Remove mature cell from the animal you want to clone.
2. Grab an egg from another animal and suck out nucleus and the genes.
3. Squeeze the genes from step 1 into egg from step 2.
4. Zap the cell with electricity, causing it to start dividing.
With luck, that's all there is to it. But cloning mammals is rather inefficient; it took 277 tries to get the single embryo that became Dolly.
Beyond basics: Ready for some fun with the cloning clowns?