Immortality – Hype or Hope?

Kate Roach

Updated February 2004

Would you like to live forever? If not, how would 150 years do you? Regenerative therapies promise to leave almost no area of medicine untouched, including ageing. They will cure Parkinson's disease, motor neuron disease, Alzheimer's disease, strokes, paralysis, heart disease and cancer. At the core of this medical revolution is the humble stem cell. Research continues apace and treatments are becoming a reality. Immortality might be within reach. But, does it foretell a utopian dream, or a torrid nightmare?

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Stem cell magic

Much of the power of regenerative medicine is in the harvesting and manipulation of stem cells. The gardeners among you will already have some experience of the power of stem cells. Ever taken a cutting from a favourite plant? It's a simple procedure – cut off a short stem, dip it in rooting hormone and stick it in some compost. Several weeks later you should have a small but perfectly formed new plant. Plants have this regenerative property because they maintain small populations of stem cells in their tissues. These cells have the magic ability to divide and give rise to all the specialised cells and tissues of the plant. By the way, the term 'stem cell' doesn't mean cells from the plant's stem.

The property of plants to grow root cells and leaf cells from other mature tissues has long fascinated researchers. The holy grail of medical research has been to discover human and animal cells that can do the same thing. Humans, it turns out, do have stem cells, although they are trickier to manipulate than plant cells. They are present in the early embryo and also in the bone marrow, skin, gut, brain and liver of adults.

To date, embryonic stem cells have been considered the ultimate in their ability to regenerate and to produce all the specialised cells of the body. They are the most flexible for therapeutic purposes. But they are ethically contentious because five-day-old human embryos have to be destroyed to obtain them.

The adult stem cells have always been more limited in the range of cell types they can produce. But this picture is beginning to change. In June last year a group of US scientists, announced the discovery of a new type of adult stem cell that might turn out to be as versatile as the embryonic sort and a good ethical alternative. These cells can be harvested from adult bone marrow.

Subtle differences between the newly discovered adult stem cells and the embryonic ones may affect how they act therapeutically – a problem that is likely to occupy many man-hours of science. Whatever, stem cell research is moving on and therapies are fast becoming reality. A reality that has the potential to revolutionise medicine, our attitudes to death and dying, and the very fabric of our society.

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