Stem cells are
cells that have three basic properties. They are not specialized and have
none of the specific functions of adult cells. They can self-replicate for
long periods of time without differentiating, unlike cells such as nerve and
blood cells. They can also differentiate to become any one of a variety of
specialized cells. (NIH & DHHS, Stem cell basics, 2006)
Stem cells can be found in embryos as well as fully formed animals. Embryonic stem cells are found in the inner cell mass of the blastocyst, while adult stem cells are found in many organs among specialized cells. Adult stem cells are a small percentage of the cells in the body. Embryonic stem cells can generally proliferate for longer than adult stem cells in labs. Embryonic stem cells are pluripotent, while adult stem cells are only multipotent. Adult stem cells generally differentiate into the type of tissue they are in, but it has been found that they have some plasticity and may differentiate into other cell types besides their normal ones. (NIH & DHHS, Stem cell basics, 2006; Univeristy of Wisconsin-Madison, Embryonic stem cells, 2006)
The field of stem cell research is a very new area, but there have been some stem cell cultures raised in labs. Scientists, after extracting embryonic stem cells from a blastocyst, raise them in culture dishes filled with a nutrient-rich medium. Once there is a large group of stem cells, they are tested to make sure they are healthy stem cells. Scientists then may try to differentiate them into specific cell types, although little is known about the processes to do this. (NIH & DHHS, Stem cell basics, 2006)
Stem cell technology has the potential to be applied in many ways in the future. Certain diseases such as diabetes and Parkinson's result from the lack of only a few cell types. Stem cells could be differentiated into the required cell type and implanted into the patient to cure one of these diseases. (Univeristy of Wisconsin-Madison, Embryonic stem cells, 2006) Stem cells could also be used for drug testing, especially for types of cells such as heart cells that are not currently available (Yu & Thomson, 2006). Stem cells would also give us a look at early human development which may help us cure or treat birth defects, pregnancy loss, and infertility. (Univeristy of Wisconsin-Madison, Embryonic stem cells, 2006)
Ethically, stem cell research is good because it has the potential to alleviate human suffering. However, there is also the problem that embryonic stem cell research, which holds much more promise than adult stem cell research, involves the destruction of embryos. We must weigh this advantage and disadvantage against each other to determine whether stem cell research is morally allowable or not. (Australia, Department of the Parliamentary Library, Rickard, 2002)
Generally, countries' laws permit the use of excess in vitro embryos for stem cell research with certain conditions. These conditions usually are that the embryo was created for and is no longer needed for reproductive purposes. Also the donors of the embryo must give written consent, and there must have been no money involved in the donation.
