Episode 23: September 28, 2012
by Lee Falin, PhD
Stem cell research is a close contender with genetically modified foods as one of the most controversial areas of scientific research. But what exactly is stem cell research and why are so many people against it?
Sponsor: The podcast version of this article is brought to you by Stitcher. With free Stitcher SmartRadio
you can listen to this and thousands of other podcasts on your mobile phone. Use promo code QDT.
The Birds and the Bees
As you hopefully have been told by now, you started out your life as a single cell. As I mentioned in my episode on interspecies breeding, this cell, called a zygote, is formed when one of your father's sperm cells fuses with one of your mother's egg cells. You'll need to ask your parents if you want more details on how that fusion occurs.
That single cell divided, and divided again...and eventually formed a mass of cells called a blastocyst. The outer wall of the blastocyst eventually fused with the wall of your mother's uterus to form the placenta. The inside of the blastocyst is mostly hollow, with a small mass of cells called the embryoblast, which eventually went on to form the embryo which became you.
During the beginning of this process, all of the cells in the embryoblast were identical. As they continued to divide, they started to differentiate, becoming specific types of cells depending on what part of the body they would end up forming. Eventually these groups of differentiated cells would clump together to form tissue that would in time form organs. So in the end, you wind up with lots of different types of cells (bone, heart, brain, liver, skin, etc.) that all started out, or stemmed from, a single type of cell. This initial cell is called a stem cell.
Now, as you know, most of us are fortunate enough to have bodies with relatively powerful healing properties. If you get a cut on your arm for example, it eventually will heal. The blood cells you lost will regenerate, new skin cells will form to close the cut, and after a while, you'll be as good as new, plus or minus a little scaring.
This healing comes from the fact that certain organs have specialized stem cells inside of them. Your bones have hematopoietic stem cells, which are stem cells that can form different blood cells. Your skin has stem cells, which allows it to form new skin to heal cuts.
Unfortunately, not all of our organs have this ability. For example, the heart is particularly bad at healing damage, as is the brain, spinal cord, and many other vital organs. And while some creatures such as salamanders have the ability to re-grow their limbs, this is currently beyond our body’s ability.
Stem Cell Research
But one thing that scientists have wondered about for decades is if all of your cells came from stem cells, shouldn't there be some way of using stem cells to regenerate damaged tissue? For example in Scotland recently, two people had stem cells injected into their eyes as part of a clinical trial to repair their corneas and restore their sight. What if this technique could be applied to repairing heart damage, or spinal cord breaks, or brain damage that occurs from strokes? The possibilities are endless.
So if stem cell research is so awesome, why are so many people against it? Unfortunately, this is because the only way to obtain high quality stem cells is to suck them out of fertilized blastocysts. The trouble is that many people find this unacceptable.
Since some groups believe that life begins at fertilization, they consider the purposeful destruction of a blastocyst in the name of science to be akin to murder. Other groups say that it's okay to use a blastocyst up until it is two weeks old, because that is the last chance a blastocyst has to split into twins (the argument being that if a blastocyst can split into twins, it really isn't a person yet). Others say that life doesn't really start until 40 days after fertilization.
Most stem cells being used in research today come from either in-vitro fertilization patients who have donated their unused blastocysts, or by using donated egg cells.
There are alternatives to embryonic stem cells, of course. As I mentioned, adults have stem cells in various organs, too. Unfortunately, these appear to be very limited in the types of cells that they can create. (For example, the hematopoietic stem cells in your bones can only make new blood cells). Another alternative is to do research on animal stem cells, which is a very active area of research. Unfortunately people aren't rats, (most of them anyway), and so a certain treatment that helps rats might actually be toxic to humans.
There you have it, stem cell research in a nutshell. If you have more questions about this controversial research area, please leave them in the comments orsend me an email at email@example.com.
If you liked today’s episode, you can become a fan of Everyday Einstein on Facebook or follow me on Twitter.
Blastocyst and Scientist images courtesy of Shutterstock