- The Observer,
- Sunday September 7 2003
Stem cells are the source of all cells - brain, skin, heart and others - that make up the human body. Just like a plant stem that branches into leaves and flowers, stem cells branch out to form different bits of our bodies.
There are two basic types:
· Adult stem cells act as a pool from which the body can repopulate itself with cells when old ones die out. When a skin stem cell divides, it forms a skin cell and another skin stem cell. The latter is retained as a future source of skin cells; the former migrates to the body's surface and takes its place among other skin cells.
· Embryonic stem cells are created in the first two weeks of life and are the source of all cells that make the growing foetus.
Although scientists acknowledge they have much to learn about stem cells, they already see ways to exploit them, for example in setting up stem cell banks to provide transplant materials for patients.
Several thousand lines of embryonic stem cells could be created to establish such a bank, each originating from an excess embryo created when a woman undergoes IVF treatment. These cells will be grown and kept in culture dishes. Patients would be given stem cells matched as closely as possible to their immunological make-up. For a diabetic, they would be injected into the pancreas where, coaxed by drugs, they would be transformed into insulin-making cells.
Immunosuppressant drugs may still be required when transplanting embryonic stem cells, and doctors are planning improvements. One method is to isolate an individual's own adult stem cells - say their dopamine stem cells - and grow them in laboratories. These would be re-injected, in this case into a Parkinson's patient's brain, where they should restore their lost dopamine production.
Ultimately, scientists hope to take a skin cell and transform it into a brain cell that could be grown and re-injected into a patient's brain - a technique that would simplify cell isolation and avoid problems of rejection. Scientists insist that this means using embryos as sources of stem cells.
