Sigh, I just can't help but comment when people use loaded words like "killing children" and "babies" when they are talking about embryonic stem cells. I would like to make a correction to this.
Embronic stem cells (ESC) are extracted from an fertilized embryo that is only a couple days old. This is a hollow ball of cells containing a smaller clump of cells inside. The wall of the ball, called the trophectoderm, forms the placenta and extra-embryonic tissue. The clump of cells inside the ball is the "inner cell mass" and are ESCs. These are, by definition, not any particular tissue and are very similar or identical to one another. This embryo does not have a human heart to beat, nervous system to be conscious or feel pain, or any defined tissues of any kind (they do NOT have a body or features). They are physiologically-speaking incapable of experiencing pain or suffering and have absolutely no consciousness."But they have the POTENTIAL to be a person" is an argument to defends the position that ESC research is unethical and destruction of life. Well, most of the embryos that would be used for this type of research are surplus embryos that are donated by couples finished with their families and that would be incinerated as biomedical waste. In the absence of injecting that frozen embryo into a pseudo-pregnant (hormone treated woman), it has ZERO potential of becoming a human. So, I would argue that this is not destruction of life.
Sorry, whew, that was a tangent and a half. The difference between the two kind of stem cells is that the ESCs, being extracted from the mass that produces every single cell in the body.....they can theoretically be coerced in the culture dish to turn into every single cell in the body, without exception (a property known as pluripotency). There are other sources of stem cells found in the adult but these usually have very refined potential, and can often only make cell types from the organ (and perhaps a few others. This is known as multipotency). For example, bone marrow contains stem cells called hematopoeitic stem cells (HSCs) that make all of your blood cells, but they can make other types as well, including cardiac muscle. Although there is evidence that they can make neurons too, it is unlikely they can produce all of the estimated 800 differenct types of neurons that make up your central nervous system.
Chord blood stem cells are the same deal. They are stem cells that are produced from a mature source and therefore are probably limited to only a relatively small number of cell types they can produce, compared to ESCs.
|