THE MOST FAMOUS sheep in the world, Dolly, was a clone. Ever since she was created in the Roslin Institute in Scotland in 1997, the scientific community and public have been somewhat obsessed with the idea of cloning animals, including humans. Since Dolly other animals have been cloned including mice, sheep, cows, goats, pigs, rabbits, monkeys and cats and even the milk and meat from offspring of cloned animals has been approved for human consumption, in the EU and US.
But it is the concept of human cloning which really captures our imagination, and several movies have been made with human cloning as the theme, including The Island or TV programmes like Star Wars – The Clone Wars (pictured above). Is it all science fiction? Actually no. The idea that humans could be cloned is not beyond possibility but there are some ethical and scientific issues surrounding it. For instance, the movie The Islandfeatures a cloning farm where human clones are produced for use as spare parts; making the point that human cloning could be abused.
Scientists have various ways of cloning including reproductive cloning, therapeutic cloning and DNA cloning.
Dolly the sheep was produced by reproductive cloning techniques. This involves a process called somatic cell nuclear transfer, where the DNA of the animal you want to clone is removed from one of its cells and inserted into an egg, whose nucleus has been removed. The egg is then stimulated with an electric current to start it dividing. Once the embryo reaches a certain stage it is implanted into a female host where it stays until birth.
The success rate for this technique is low and less that between 1-4 per cent of nuclear transfers are successful (Dolly took 275 attempts). A human clone would be made this way.
DNA cloning is much more common and involves the insertion of a small section of DNA (called a gene) into a host cell, usually a bacterium. This technique has been around since the 1970s and human genes are often inserted into bacteria. It is used to make a wide range of useful materials such as human hormones (eg insulin for diabetics), vitamins, antibiotics and crops resistant to certain herbicides.
But the third category, therapeutic cloning, has enormous potential for medical advances. Therapeutic clones are also produced using somatic cell nuclear transfer but this time the embryos are not inserted into a host female. Instead they are used to make stem cells.
Stem cells are cells in your body which have the potential to be any type of tissue, eg nerve, muscle or skin tissue. In theory these stem cells could be used to produce replacement organs, such as hearts, liver, kidneys or skin, or to grow nerve cells to cure diseases, such as Alzheimer’s and Parkinson’s disease, or even help relieve the symptoms of brain damage or strokes. There would be no chance of organ rejection either, as the cells are genetically identical to your own.
But the ethical issues don’t go away with therapeutic cloning. Many people believe that life begins at conception and so the use of somatic cell nuclear transfer involves the creation of human life. Using these cells for research or the creation of spare parts raised huge ethical concerns for many.
The moral questions surrounding human cloning has led many countries to ban it. Reproductive cloning has been prohibited by the EU, Australia and several US states. But, several countries, including Australia and the UK, make research into therapeutic cloning legal although the area is carefully regulated. Various religions condemn human cloning.
So human cloning hasn’t been invented for a number of reasons. First it’s hard to do. Second, are the moral and ethical challenges. But who knows, we may well see human clones used to manufacture replacement organs in the future? Only time will tell.
Find out more: Why is Cloned Meat So Hard to Swallow? url.ie/a4wo