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BW Businessworld

Cells Of Hope

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Regenerative medicine crossed another milestone this week when scientists at the University of Lund in Sweden demonstrated the direct conversion of skin tissue cells into nerve cells. So far, the standard technique in this field has been to convert adult cells (usually from the skin) into stem cells, and then converting stem cells into tissues or organs that have to be transplanted. This method has several risks and has not worked well in humans so far, although a few recent breakthroughs seem promising. The new method skirts the stem-cell route, and so avoids most of the risks associated with it.

Regenerative medicine is in some ways the Holy Grail of modern medicine. Damaged organs such as kidney, liver or the retina can seldom be repaired through drugs. The only way out is to transplant a new organ. This works for some time, but brings with it other risks such as rejection. The average life expectancy of a patient with a transplanted kidney, for example, is 10-15 years. Regene-rative medicine can one day provide these people with their own organs, but so far it has not worked to the extent required for field use.

Regenerative medicine is useful not just in transplanting organs. Bone marrow transplants are being used to treat leukaemia patients. Many neural diseases can in theory be treated with regenerated cells. For example, Parkinson's disease, caused by degeneration of brain cells that produce a chemical called dopamine (an important neurotransmitter involved in many brain functions) can, in theory, be treated by transplanted brain cells. However, this method has not worked in practice so far.

The use of stem cells in regenerative medicine has been dogged by several controversies. The use of embryonic stem cells has been criticised as unethical and has been banned at various times in several countries. Scientists have learned to convert adult cells — particularly of the skin — into a type of stem cell called pluripotent cells (which are capable of differentiating into most organs in the body), but the use of pluripotent stem cells in therapy is dangerous because they sometimes lead to tumours. The current method in Lund avoids this step, and converts cells of one type directly into cells of another type.

The Lund scientists have achieved this by reprogramming the skin cell, of a type called fibroblasts. Cells differentiate into different types because different kinds of genes become active in different kinds of tissues. You can use this process to change cells of one type into another. For example, if you shut down the liver genes in the liver cells and activate the retina genes, the liver cells will be converted into retinal cells. Lund scientists, led by Malin Parmar at the department of developmental neurology, found that this technique was much easier than people thought.

Parmar and her team activated three nerve cell genes in the fibroblasts, and another two genes involved in dopamine synthesis. This led to the conversion of the fibroblasts into dopamine-producing nerve cells, thereby demonstrating a possible therapy method for Parkinson's disease. This was a major breakthrough because it opened a new avenue of research with immense potential. For scientists to actually use it in a clinical trial, they need to see how the new neurons grow in the brain. They need to optimise their methods with the right kind of starting cell, see how well the new neurons grow in the brain, whether they survive in the long term, and also how well they produce dopamine. Of course, they would also need to see whether the patients get better with the treatment.

(This story was published in Businessworld Issue Dated 27-06-2011)