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8 Genetic engineering: Medicine What is your view of medical progress? Discuss the question above with a partner. Make sure you deal with the following aspects: • Is it right to test new methods of treatment on animals and/or humans? • Should people interfere with nature? • Who should take the decision to determine which medical treatment is ethically acceptable? Reading: How stem cells can turn back the biological clock Read the text about stem cell therapy. Some parts are missing. Choose the correct part (A–I) for each gap (1–6). There are two extra parts that you should not use. Write your answers in the boxes provided. The first one (0) has been done for you. Breakthrough discovery by Edinburgh researchers. Finding offers hope of replacing damaged organs. 1 2 British scientists have discovered a secret ingredient which gives stem cells the power to grow into any tissue in the human body. Stem cells are believed … 0 , but the biological machinery that allows them to form anything from nerves to liver and skin cells has until now eluded scientists. The finding paves the way for potentially radical changes in medicine. Ultimately, it could let researchers take skin or other cells from a patient and convert them into stem cells. With further work, these could be grown into tissues and organs … 1 . Researchers at Edinburgh University made the discovery during experiments in which stem cells taken from human embryos were fused with brain cells. Occasionally, when the two cells fused, the brain cell was converted into a stem cell. Effectively, the stem cell had turned back the clock on the brain cell, rewinding it to the earliest stage in its development. “We knew that stem cells could rewind other cells, but we had no idea how they did it,” said Professor Austin Smith, who led the study. To investigate, the researchers repeated the experiments after boosting levels of a gene inside the stem cells. The lab named the gene “Nanog”, after Tir nan Og, the Celtic mythical “land of the ever-young”. The tests, reported in the journal Nature recently, showed that every time a brain cell was fused with a stem cell boosted by Nanog, it was converted into a stem cell. The researchers believe that Nanog, alongside other genes, kicks into action a cascade of complex biological machinery that forces cells back into their simplest state, before becoming one of the 200 cell types found in the body. Previous studies have found that Nanog is first expressed on the third day of life, when a fertilised human egg is no more than a ball of cells. At the same time stem cells form, which go on … 2 . “The dream here is that if you have a patient with Parkinson’s disease or type I diabetes, where particular types of cells have died, then maybe we could take skin cells from the patient, expose them briefly to Nanog and convert them to embryonic stem cells. You then grow those up, convert them into replacement cells and … 3 . Because they are identical to the patient’s own cells, there is no danger of them being rejected by the immune system,” said Professor Smith. Such radical new therapies are likely to be many years away, but unlocking the secret that gives stem cells their versatility brings hopes much closer. Some researchers believe that by understanding how stem cells work, they will eventually be able … 4 stimulate healthy cells in damaged organs to regenerate themselves. “This is probably the $64 billion question when it comes to stem cells, but it’s not a simple question and 5 10 15 20 25 30 35 40 45 50 55 60 65 70 94 Science and technology Nur zu Prüfzwecken – Eig ntum des Verlags öbv