Self repair.

Some species have great capacity for self repair, being able to re-grow tails and even limbs but human capacity is limited. However, advances in biotechnology make it possible to grow human tissue so that skin can be grown for the treatment of burns and a human ear was grown on the back of a mouse, by means of a plastic implant seeded with living cells. The discovery of the gene responsible for growing blood vessels made it possible to inject this gene into the heart of a man suffering chronic angina and he is now free from angina attacks. But another patient died soon after a similar operation - whether the treatment was responsible for his death is not yet known. It is possible that humans may already carry the potential for greater self repair in stem cells left over from the embryonic state; the problem is how to utilise them. The brain contains neural stem cells which may account for cases of spontaneous recovery from brain damage. If neural stem cells could be used to repair damage to the spinal cord this would be a great medical breakthrough as serious damage to the spinal cord results in paralysis and no way of overcoming this has yet been found.