This post is an attempt to explain what stem cells are, and the differences between the different types. I am not going to touch on the ethics of stem cell research in this post, but leave that for a later discussion. I do think it is important that people understand what a stem cell is before they are able to make a judgment call on the ethics surrounding the subject. That may sound obvious; but experience has shown me that again, and again, people (including very powerful people) will make a really serious decision, without fully understanding the issue behind stem cells.
I am also going to try to keep this short and therefore I may be accused of over-simplifying. I apologise in advance for that, and should be able to give more information if anyone requires it. I am not going to talk about the research at this stage either. It is just looking at the stem cell themselves, what they do, and where they come from.
Almost all living organisms have stem cells. The name comes from the fact (like a plant) these are the stem, that have the capability to produce different types of cells & therefore tissue. They are of course the cells which allow animals to grow (both in the womb, and later in life). They are also the cells which allow our bodies to repair damage. So if you want to see them at work, then you can cut yourself. Eventually the cut will heal over, and new tissue will be grown to heal the cut. Clever things…we would be in trouble without them.
Now there are different types of stems cells, and they are identified by the number of different types of tissue that they are able to produce.
- Totipotent - can produce any cell within the body
- Pluripotent - can produce almost any cell of the 3 germ layers.
- Multipotent - can produce any cell of a particular family of cells
- Unipotent - is only able to produce one type of cell
The potentially most useful cells are the ones that can produce the most type of cells - the first 2 (actually the focus is mostly on pluripotent) groups. And indeed it is these cells (and how they are harvested) that cause almost all the controversy.
In humans, pluripotent stem cells are taken from blastocysts, which are 3-5 day old embryos. The embryos are provided by fertility clinics. When females are receiving certain fertility treatments then they are given drugs to cause them to super-ovulate (or to produce many eggs). These are removed from the uterus and fertilised with the sperm. In other words, these embryos have never been inside a human body and would never go on to produce a foetus. If they were not to be used for stem cell research then they would be discarded, thrown out with any other organic waste.
A really exciting recent development from 2 separate pieces of research from last year, is the possibility to use adult multipotent skin stem cells, and alter them so that they could become pluripotent. Should this technique be fully successful, then it may remove almost all of the objections that people may have against stem cell research.
In the next post I would like to discuss the different research areas, and the lists of diseases / impairments / medical advantages that may be possible through this research. I think only when there is a full understanding of the facts, and issues that we can then go on to discuss the ethics.