The value of the scientific discoveries which have had the biggest impact in the quest to prolong human life is universally accepted. Vaccinations are routinely used as a shield to protect us from potentially lethal diseases. Antibiotics are commonly - perhaps too commonly - dispensed to destroy harmful bacteria. Outside of the medical field, improvements in sanitation have saved many lives. A breakthrough by South Korean scientists last week has similar life-saving potential. But the achievement is highly controversial. This is because it is in the sensitive area of stem-cell research. The team in Seoul, led by Hwang Woo-suk, was the first in the world to clone a human embryo last year. On Friday, it revealed it had created the first embryonic stem cells which genetically match patients suffering disease or injury. This is a big step forward in research and will, hopefully, see stem cells used to cure heart disease, cancer and Alzheimer's disease, among others. The genetic match makes it less likely future stem-cell treatments would be rejected by the immune systems of patients receiving them. The research has rightly been acclaimed by scientists around the world as an important and exciting achievement. One pioneer in the field went so far as to describe it as a scientific revolution. But the research has been labelled by its critics as morally offensive and 'Frankenstein science'. Certainly, it gives rise to difficult ethical and moral issues. This is because stem cells are harvested from human embryos. Opponents argue that even when these embryos are created in a laboratory, they are an early form of human life - which is destroyed during the experiments. The embryos created in South Korea were, however, not the product of fertilised eggs and were only a few days old. They were no more than a cluster of cells. The suggestion by United States President George W. Bush that this type of research involves 'taking life to save life' is not, therefore, a convincing one. There are also concerns that research of this kind could lead to cloning for reproductive purposes. It could potentially allow people to make carbon copies of themselves. Few would disagree that such research should be banned. But the quest for medical knowledge which will save and prolong life should be supported - and encouraged. There is certainly a need for the work to be undertaken in a safe and ethical manner. The South Korean team is acutely aware of these issues. It is opposed to reproductive cloning. And the scientists have conducted painstaking ethical reviews of their work. They are blazing a trail in this promising area of medical science. Their success has been possible because of the relatively relaxed rules on stem-cell research in South Korea - and also the funding the team receives from the government. Not all nations provide scientists in this delicate field with such encouragement. Many impose very tight restrictions. Indeed, the United Nations issued a non-binding statement in March calling on all governments to ban stem-cell research. But the debate goes on. This week the US Congress will debate a bill which aims to relax the very strict limitations imposed by Mr Bush in 2001. Stem-cell research holds out the hope of achieving spectacular medical advances which could save millions of lives. Despite all the controversy, it is destined to become a huge field of medical science. Governments should be focusing on how best to ensure that such research can continue - in a safe, ethical environment. And that includes Hong Kong, where tight regulations act as an impediment to progress. The South Korean scientists are leading the way. Most of the world will, in time, follow their example.