Cloning and Research

Stem cells are cells in the very early stages of life that have the potential to become any type of cell, for example - a nerve cell, or a muscle cell. There is a lot of excitement about stem cells, as they be could be used to repair damaged organs, regenerate defective parts of the brain and spinal cord, or even eventually be made into complete organs for transplantation.

Stem cells come from two sources - early embryos, where they are destined to become all the different cells of the body - or adult tissue.

Embryonic stem cells are obtained from embryos left over from IVF. They is a huge amount of controversy surrounding embryonic stem cell research, as it ultimately means pulling apart an embryo that could have been a new life. Stem cell research has been restricted in some countries, including the US and Germany.

In countries where these restrictions are in place, the main focus is now on adult stem cells. But the problem is that isolating adult stem cells is very difficult, as they are not as easy to manipulate as embryonic stem cells.

There have, however, been some very successful trials using adult stem cells, including a trial at the Texas Heart institute in conjunction with the Pro-Cardiaco Hospital in Brazil, where they are using adult stem cells taken from bone marrow to treat people with severe heart disease. These stem cells are repairing the damaged areas of the heart by becoming new muscle and blood vessel cells.

The ultimate goal is to grow complete organs for transplantation. This is what is being done at Tokyo University by Professor Asashima, who is using frog stem cells to grow complete organs. He has succeeded in growing 15 organs, including, eyes, heart, kidneys and cartilage tissue. He is now attempting the same with mice and has so far succeeded in growing simple tissue such as skeletal muscle cells.

Cloning
Cloning is the process of making a genetically identical organism. It requires removing the DNA from an adult cell, such as the skin cell, and placing it into an unfertilised egg that has had its DNA removed. The cells are then fused together with an electric shock (which mimics the egg and sperm coming together in sexual reproduction) and the cell begins to divide.

Cloning is so difficult to get right because the skin cell the DNA is taken from needs to be taken back to an embryonic state to allow the egg to grow into a foetus.

Many animals have already been cloned, including sheep, goats, cows, pigs and a cat, but a lot of these cloned animals seem to be defective in some way. A company called Clonaid claim to have produced three cloned babies, but this has not yet been verified by an independent genetic test.

Primates seem to be more difficult to clone than other animals and past attempts at cloning human embryos for therapeutic purposes have so far been unsuccessful.

But it is only a matter of time before the technique is mastered. Cloning does not require complex instruments - only the sort of equipment currently found in most IVF clinics. All it would take is a plentiful supply of eggs and a team of scientists willing to go for it, despite the risks. At present there is only a 2% success rate, with 98% of the attempts resulting in deformed animals.

Did you know?
Dolly the sheep is named after country and Western singer Dolly Parton, as Dolly the sheep was cloned from a mammary cell. Dolly gave birth to four lambs, including Bonnie in April 1998, followed by three more lambs in 1999.