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Our Little Builders
DR REBECCA KEOUGH - MOLECULAR AND BIOMEDICAL SCIENCE
The Advertiser
29 June 2006
Stem cells have the potential to repair just about any part of the body.
STEM cells are the tiny heart of a furious world-wide debate. Their potential to heal is enormous. But one of their sources is contentious: human embryos. Yet not all stem cells need come from embryos. Some types live in all of us.
All stem cells offer exciting opportunities to medical science. For they hold the blueprints for making the many and varied cells that make up the body.
In the laboratory, researchers can direct stem cells to make the type of tissue needed to replace cells damaged by disease or accidents.
Potentially, conditions ranging from neurological diseases (such as Parkinson's disease) to Type 1 diabetes, spinal damage and heart-attack damage could be treated using stem cells. The task science faces is finding the right signals to send the correct stem cells to stimulate them to produce large amounts of the necessary specialised cells.
Stem cells are "unspecialised", waiting around, not doing much, until they receive instructions to convert themselves into a particular type of cell, such as muscle.
We all have adult stem cells in our bodies that replace tissues which are constantly turning over such as skin, hair and blood.
But adult stem cells have already received some of their instructions and are therefore limited in the kind of cells that they can become.
Blood stem cells can only develop into different types of blood cells and so on.
Nor do all parts of the body have a reserve supply of adult stem cells.
Science has not yet found adult stem cells for the kidney or the heart. This may be why the body can't replace the dead cells when these vital organs are damaged.
Embryonic stem cells are, however, much more adaptable. They are found in the very early embryo and only last about 4-7 days after fertilisation of the human egg.
These stem cells are the founder cells from which all the cells of the body are produced.
When grown in the laboratory, embryonic stem cells retain this potential to form almost any type of cell if given the right signals.
So, do stem cells hold the promise of new cures? Using stem cells to treat patients is not new. Bone marrow transplants work because blood stem cells present in the transplanted marrow are able to keep making new blood cells.
What is new is the versatility of embryonic stem cells to produce any type of cell needed. This could lead to the growth of cells in the laboratory, such as heart muscle cells, for treating heart-attack victims.
A key to the success of stem cells is to be able to manufacture large numbers of the cell that is needed for transplant, without other kinds of cells being made as well.
Although we know many of the signals that are needed to direct a stem cell down a particular path, some still get lost along the way, resulting in a mix of different cells. Basically, whenever a stem cell meets a fork in the road, we need to supply a molecular policeman that will send it in the right direction.
Medical science is focussed on discovering this precise set of instructions needed to make stem cells form particular types of cell.
It may even be possible to give these signals to a patient to stimulate their own stem cells in healing their injuries - such as activating neural stem cells to replace damaged brain cells.
Once we have detailed roadmaps for different cell types, the distance from stem cell to therapy becomes even shorter.
Dr Rebecca Keough is a Research Fellow in the School of Molecular and Biomedical Science at the University of Adelaide.
Building blocks
* Cells talk to each other. Stem cells are particularly sensitive to signals from other cells and their environment. These signals tell the cell to remain as a stem cell or direct it to become a particular kind of cell.
* To help embryonic stem cells form neural cells, muscle or blood etc in the lab, the cells are initially grown in clumps, called bodies.
* Looking at the bodies under a microscope is one way to tell if other, unwanted cell types are also present. These unwanted cells could send signals that change the fate of the rest of the cells.
* Two types of photograph are shown here. Scanning electron microscopy of a body shows all the cells on the outside are the same. Fluorescence microscopy
shows cells that can make muscle and blood are sometimes found with cells that have been directed to make neural tissue.
These photos are featured at the Science Meets Art exhibition, a free photographic exhibition featuring images of cells at the Barr Smith Library, University of Adelaide, until July 16.
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