A primer on how stem cells work

Think about some of the big medical breakthroughs that have changed the human condition for the better.

There is the invention of the vaccine, which has nearly eliminated deadly viral diseases such as smallpox, polio, measles and mumps. There's the rise of antibiotics, which can rapidly heal all sorts of bacterial infections. There are surgical procedures such as heart surgery and brain surgery. Even the common appendectomy has saved millions of lives.

Those are all huge medical advancements, many of which we now take completely for granted. Together they have helped to double the average human lifespan.

Stem cell research promises to open up a new area of medical advancement that has the potential to be just as important. Once we understand and harness their full potential, stem cells may improve millions of lives. Which leads to the obvious question: What is a stem cell?

Here is a simple definition: A stem cell is a cell that has the potential to turn into many different kinds of cells.

To understand that, think about your own body. It contains dozens of different cell types. You have skin cells, which are completely different from liver cells, which are different from the cells that create tooth enamel, which are all different from muscle cells. But all those different types of cells came originally from stem cells.

You started out in your mother's womb as a single cell, a fertilized egg.

That little spark of life divided into a tiny clump of stem cells (known as embryonic stem cells). Then those stem cells started dividing and differentiating into the specific cell types that make up your body today.

Obviously stem cells were important when you were developing in your mother's womb, but how can they be therapeutic for you today? Let's look at a few examples.

The idea of a bone marrow transplant is actually a stem cell therapy of sorts. Bone marrow contains stem cells for creating new red and white blood cells. But in certain diseases, the bone marrow stops doing its job correctly. Or bone marrow can be destroyed in the process of treating an aggressive cancer. So the stem cells in the marrow are replaced with new stem cells from a donor.

One classic situation where stem cells will probably be useful is the treatment of Parkinson's disease. Parkinson's disease is caused when a certain type of brain cell (called a dopaminergic neuron) stops working. Dopaminergic neurons produce dopamine, and without dopamine your brain loses its ability to control your muscles. The hope is that stem cells can be injected into the brain, and that they can differentiate into the proper types of cells to replace the lost dopamine.

Another place where stem cells might help is in the treatment of paralysis. Imagine that you were to fall and sever your spinal cord. Depending on where the break occurs, this accident will paralyze your legs or your arms and legs. You will be paralyzed for life because the nerve cells in the spinal cord will not grow back on their own. With stem cells, there may be a way to coax new cells to repair the damage.

Another area of stem cell research is organ replacement. Since stem cells are undifferentiated, they have the potential to turn into specific cell types. What if you could coax stem cells into growing a new heart or a new kidney?

One of the first successes in the new era of organ replacement came in 2008, when scientists grew a woman a new wind pipe using stem cells. They started with a piece of donated wind pipe three inches long. They stripped off its outer cells to create a scaffold for new cells. Then they seeded the scaffold with stem cells from the woman needing treatment. The stem cells covered the scaffolding and created a new piece of windpipe that her body would not reject. Surgeons inserted the replacement windpipe and eliminated a significant problem for her.

It is easy to imagine many new techniques that become possible with stem cells. But at this moment, the research in this area is still very new.

Scientists and doctors have a long way to go before they completely understand stem cells and how to use them. It is hoped that, by opening up research, new treatments will become available in the near future.

 E-mail this story   Printer-friendly version  

Copy and paste the link: