Monkey Cloning

Scientists in Oregon have made stem cells from cloned monkey embryos
November 14, 2008 Scientists in Oregon have successfully cloned a monkey. On the face of it, this doesn't sound like that big of news. After all, scientists have already cloned sheep, mice, cats, dogs and lots of other animals too. And these researchers didn't even grow a whole new monkey. So what's the big deal? The big deal is that this is the first primate that has ever been cloned. Which means it is the first step towards human cloning*. This is not important because scientists want to clone Albert Einstein, Ted Williams or even Pavorotti. No, the reason scientists want to clone humans is to make personalized embryonic stem cells. With these sorts of stem cells, doctors can cure many diseases and heal severed spinal cords without tissue rejection. *Earlier claims of human cloning by Dr. Huang Woo-suk were not correct.
How to clone a monkey
In many ways, cloning a monkey is just like cloning any other animal. Basically, all a scientist needs is some monkey DNA, a monkey egg and some experience with very expensive equipment. First, a monkey cloner needs some monkey DNA. This makes sense since DNA contains all of the instructions for making a living organism. In fact, it is even "written" in a code that uses four letters—A, G, C, and T. So monkey DNA has the instructions for making a monkey.

Fusing an egg without a
nucleus with an adult cell
makes a clone.
But scientists can't just read these instructions and create a new monkey. Only a cell can read all of the DNA of an animal all at once. And the cell can't do this with the kind of naked DNA you can get out of a strawberry at home. A cell needs DNA in its natural environment—in the nucleus of a cell. So the first step is really to get a monkey nucleus. The second step is to remove the nucleus from a monkey egg and to replace it with the adult monkey nucleus. What scientists actually do most of the time is to fuse the adult cell with the egg that is missing its nucleus. But the end result is the same—an egg with a new nucleus. So now the scientist can just grow the fused egg up and make a clone, right? After all, every cell has the same DNA so all the instructions for making a monkey are now in the egg. Except that it won't work because all DNA is not the same. All the letters of DNA are the same between one cell and another in any single animal. But the DNA is used differently in different kinds of cells. And the cells "mark" up DNA differently depending on how they use it. These marks affect how the DNA is read when it is moved to a different cell. So the DNA of a skin cell is marked differently than the DNA of a liver cell, or a muscle cell, or any other kind of cell. To successfully clone an animal, these markings need to be changed from an adult cell to that of a fertilized egg. And this is what the group in Oregon successfully did. They removed the nuclei from 304 eggs and fused each egg to an adult monkey skin cell. Of these 304 eggs, thirty five were successfully made into an early embryo called a blastocyst. The scientists could have then implanted these blastocysts into a surrogate mother to try to grow a new monkey. But that wasn't the purpose of the research. Their purpose was to make embryonic stem cells.

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Cloning as a source of embryonic stem cells

Embryonic stem cells
can become any other
kind of cell.
Embryonic stem cells have the potential to cure many diseases. Diabetics won't need insulin anymore. Paraplegics will walk again. Parkinson's will be cured. And the list goes on and on. One of the big problems with stem cells, though, is the same problem with the transfer of any tissue from one person to another—rejection. If the stem cell doesn't match up, then the body may reject it. So, an obvious answer is to use a patient's own stem cells. Adults have stem cells that are responsible for replacing worn out cells in their body. But these stem cells are limited because they can only turn into some kinds of cells. For example, blood stem cells can only become blood, not nerves. So blood stem cells could not fix a severed spine. And scientists haven't found enough nerve stem cells to repair a spine either. The best kind of stem cells to use would be embryonic stem cells except that they are long gone in an adult. Which is where cloning comes in. If an adult were successfully cloned, then that adult would have a limitless supply of embryonic stem cells. Again, scientists would not grow the clone to adulthood. Instead, they would grow it to around 100 cells or so and then make embryonic stem cells from that. Right now scientists can't clone a human cell but monkey cloning is the first step in the process. But it is only a baby step. Scientists still have a long way to go before human cloning becomes routine (or even feasible). The researchers started out with 304 eggs and eventually got 2 embryonic stem cell lines. This is too high a rate of failure to be useful (or ethical) in humans. Harvesting human eggs is an invasive, expensive process. To get 300 eggs, you'd need many, many donors. Too many to make this anything but a treatment for the very wealthy. Scientists need to either improve the odds that any given egg can be converted to a blastocyst or they need to figure out how to make an egg in the lab so they don't need to harvest them. They are working on both approaches. A third approach is a bit more radical but solves many ethical problems as well. Perhaps when a child is created using in vitro fertilization, a single cell can be removed before the embryo is implanted into the mother. Scientists could then coax that cell into growing into an embryonic stem cell line. Now if the pregnancy is successful and an embryonic stem cell line is established, the child has personalized embryonic stem cells frozen away for later use. This has worked well in mice and has been reported to work in humans as well. Once scientists have figured out how to make personalized embryonic stem cells, doctors can use them to begin to tackle all sorts of health problems.