[ASC-media] Media release: Stem cells - gateway to 21st century medicine
Australian Academy of Science
scied at science.org.au
Tue Nov 11 09:40:37 EST 2003
11 November 2003
Nova topic: Stem cells - gateway to 21st century medicine
Stem cells are a powerful new technology that can't be ignored. Proponents say they will revolutionise medicine, while opponents call them Frankenstein technology. Just what are these headline-making cells? The new Australian Academy of Science Nova: Science in the news topic has easy to understand information on stem cells at http://www.science.org.au/nova.
Most of the 3 trillion cells of the body have completely specialised functions. Blood, lung, brain, skin or liver cells are all wonderfully specialised for what they do. By and large, they cannot do anything other than what they were designed for. Stem cells, on the other hand, do not have a specialised function; they are an immature kind of cell that still has the potential to develop into many different kinds of cell. They are 'all-purpose' cells.
There is another characteristic of stem cells that makes them so prized. Unlike our specialist cells, stem cells have the capacity to keep multiplying. This capacity to both proliferate and form different types of cells makes them ideal for replacing tissue that is lost. Need new pancreatic cells to replace the one you've lost to diabetes? Let stem cells churn them out for you. That's the potential of stem cells and the reason why research scientists, biotech companies and sick people are so passionate about having the freedom to develop that potential.
Scientists distinguish between two types of stem cells: embryonic stem cells and adult stem cells. Embryonic stem cells are obtained from surplus 5-day-old embryos. Such embryos are produced in the 'test-tube' for infertile couples, but often more are produced than needed. These surplus embryos are stored in the freezer and normally thrown away after 5 years. Embryonic stem cells, derived from surplus embryos, can be programmed to become any cell of the body. They also have the capacity to keep proliferating indefinitely in a culture dish.
Adult stem cells exist in certain mature tissues and supply the tissue with replacement cells throughout life. For instance, our blood stem cells churn out 5 million cells per second! Until recently, only tissues like blood and skin, which replace themselves prodigiously, were thought to have stem cells. Now it seems that whichever organ researchers look at, they find stem cells, even when those organs don't seem to be very good at replacing their lost cells, like the brain or pancreas.
Compared to embryonic stem cells, which can make replacement cells for any tissue, adult stem cells are normally dedicated to making the cells for one particular tissue. For instance, skin stem cells usually can only make skin, not brain or blood. And when isolated and placed in the culture dish, they don't grow indefinitely as embryonic stem cells do.
Most researchers believe it is essential to carry out research on both embryonic and adult stem cells. Both have advantages and drawbacks. Researchers cannot yet say which types of cells will work best.
More about stem cells is on the Australian Academy of Science's Nova: Science in the news website at http://www.science.org.au/nova. The topic also includes a glossary; student activities; further reading; and annotated links to relevant websites.
The topic was developed with support from the National Stem Cell Centre.
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