Ben Bova: Cloning's potential shows it's more than just a funny idea
By BEN BOVA, special to the Daily News
April 25, 2004
http://www.naplesnew...2834614,00.html
Ben Bova - (Author "Immortality: : How Science Is Extending Your Life Span--and Changing The World")
Even cloning has its funny side.
When Woody Allen began work on his science fiction comedy, "Sleeper," in the early 1970s, he felt he needed a science fiction expert to check his script. I was chosen for the job.
Being a consultant to Woody was lots of fun. He isn't at all the chump he plays on the screen. He's sharp and very much in charge, although I must admit that he's more than a little neurotic.
"Sleeper" takes place 200 years in the future. The highlight of the film is the idea of bringing the assassinated world dictator back to life by cloning cells from his nose, all that was left of him after an assassin's bomb destroyed the rest of his body. Everyone thought that it was a very funny idea, cloning a whole human being from cells taken from his nose. Everyone thought that it would take 200 years before cloning could be made to work.
Well, there have already been several claims by somewhat dubious organizations that they have successfully cloned a human being. And more recently, reputable researchers from a laboratory in South Korea announced that they have cloned human stem cells, a major step toward therapeutic cloning. More on that in a moment.
But first I've got to tell you that a team from MIT and Columbia University have reported cloning mice from mouse nasal cells. Woody's "nose job" from "Sleeper" was their inspiration, they told reporters.
Score one for the funny guys.
Human cloning, though, is a serious business. Several nations, including the U.S., have either passed laws already or are preparing legislation to make human reproductive cloning illegal.
Reproductive cloning means producing an entire human being through cloning. Many ethical and religious objections have been raised against reproductive cloning, although I think many of the objections are based mostly on fear of the unknown. There are medical objections, as well.
In reproductive cloning, the nucleus of a fertilized human egg cell is removed and replaced with the nucleus from a donor's cell. The nucleus contains the donor's DNA, the genes that are the cellular blueprint that determines the physical characteristics of the baby. The microscopic cell is then placed in a woman's womb to be brought to term.
While the growing embryo has its donor's DNA, it is affected by the biochemistry of the surrogate mother. The genes interact with the environment they find themselves in. The resulting baby will not be an exact duplicate of its donor parent. Very close, perhaps, but not exact.
Moreover, carrying a cloned fetus to term might be dangerous for the surrogate mother. No one yet knows if there will be problems of tissue rejection or other unforeseen medical complications.
Be that as it may, the report from South Korea about cloning stem cells is another kettle of fish altogether. Now we are talking about therapeutic cloning. Therapeutic cloning is not intended to produce a new human being in its entirety. It is aimed at producing new cells, perhaps eventually whole new organs, to replace human tissue damaged by disease or injury.
Therapeutic cloning may well lead to a new era of medical treatment, in which diseased tissue is replaced by healthy cells grown from the patient's own cells. No danger of rejection. No side effects from drugs or radiation.
Once you were a single cell, a fertilized egg. The genes in that one cell contained all the information needed to build your heart, your brain, your arms, legs, eyes, every part of you. Locked in the DNA of every cell in your body, your genes still contain that information. They could, if properly "motivated," build replacement parts for you.
But most of the genes in most of your cells have been deactivated. And a good thing, too. You really don't want to sprout an extra arm or grow another few feet of intestines. When cells do multiply in an unregulated manner, they create tumors. That's what cancer is: cells multiplying uncontrollably.
Back when you were a single cell, that cell's genes were totipotent. That is, they could diversify into all the different types of cells that your body needed. As you grew, your cells multiplied and began to specialize into specific types of cells: skin, nerve, muscle, etc. By the time you were born, all your parts were in place, and most of the genes in most of your cells switched off, their job finished.
Yet each cell of your body still contains all the genes necessary to make a new copy of yourself. That is the basis for reproductive cloning.
Your body also contains stem cells, cells that have the ability to generate other types of cells. Stem cells are not totipotent, as your original embryonic cells were. But they are multipotent: the stem cells in your body can generate many different types of cells.
This is the basis of therapeutic cloning: using stem cells to built new tissues that can be used to replace tissue damaged by disease or injury.
Researchers interested in therapeutic cloning have been using embryonic stem cells, usually obtained from embryos discarded at fertility clinics, because these very early cells are still totipotent, or close to it. However, because of religious and political objections to using embryos, attention will inevitably focus on finding and using the stem cells that are still present in the adult body.
Adult stem cells are not as potent as embryonic cells, but they can still be used to generate many different types of body cells, which can be cloned and used to replace damaged tissue. Is your heart on the brink of failure? Grow a new one, or at least renew enough cardiac tissue to make your heart young and strong again.
One day in a future that most of us will live to see, patients will regenerate skin, nerves, whole organs and limbs from stem cells of their own bodies. Regeneration will take the place of much of surgery, chemotherapy and radiation treatments.
And probably the earliest and most lucrative use of stem-cell regeneration processes will be in cosmetic surgery. Smoother skin and tighter muscles will be obtained through tissue regeneration. No more scalpels and scars, thanks to therapeutic cloning.
Naples resident Ben Bova's latest futuristic novel is "The Silent War: Book III of the Asteroid Wars." Dr. Bova's Web site address is www.benbova.net.
