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Stem Cells. The Controversy.

Without a doubt, one of the most controversial topics of popular discussion is stem cell research. In fact, one would be hard pressed to peruse the newspaper or magazine stand without encountering some reference to the global stem cell debate--but, what, exactly are stem cells, and why are they so controversial?

Stem cells intended for use in human applications are found in embryos during early stages of development, in fetal tissue, umbilical cords, and more rarely, in some adult organs. The reason these cells are so valuable is because of their capability to produce or "become" other cell types--for example, brain cells, heart cells, skin, etc. In short, these are "master cells," holding the ability to divide in cultures, and to be manipulated allowing it to transform into any type of cell. Of course, this is extremely important due to the fact that scientists can use this capability to either create organs (thereby helping to meet the tremendous shortage of donor organs), or to create tissues to treat various diseases and disorders.

The reason the discourse surrounding the topic of stem cells these cells is so controversial is due to the fact that the most promising source of stem cells is human fetal tissue. Embryonic stem cells were first successfully isolated and cultured in 1998 by a group of scientists led by University of Wisconsin's James Thomson. Of course, in order to harvest the cells from such a source, the embryo, itself, must be destroyed. Because of this, many who hold anti-abortion views find this practice to be highly immoral and repugnant. With all of the controversy surrounding the use of stem cells derived from embryos, many wonder why research isn't conducted only on adult stem cells. But scientists say isolating adult stem cells is very difficult and multiplying them outside the body is not yet possible in most cases. In addition, there is only preliminary evidence that cells obtained from an adult organ can be coaxed into becoming different tissue types. Therefore, the reason embryo stem cells are used at all is because of their ability to transform themselves into virtually any type of cell made by the human body. The specific way this works is best described according to the process of normal embryonic development.

Of course, most people know the origin of human life begins with the sperm fertilizing the egg. After this, a single cell is created that holds all of the genetic information needed to form the entire human body. This cell divides and redivides over several days until these cells (known as totipotent, or as having "total potential") begin to specialize into the formation known as the "blastocyst," which has a hollow sphere of cells, and a cluster of inner cells (the inner cell mass). While the outer cells of this blastocyst proceed to form the placenta, the cells within the inner cell mass go on to form virtually all of the tissues and organs of the human body. It is these cells that are harvested to research stem cells.

Embryonic stem cells are of great interest to medicine and science. The first potential applications of human embryonic stem cell technology may be in the area of drug discovery. The ability to grow pure populations of specific cell types offers a proving ground for chemical compounds that may have medical importance. The study of human development also benefits from embryonic stem cell research. The earliest stages of human development have been difficult or impossible to study. Human embryonic stem cells offer insights into developmental events that cannot be studied directly in humans in utero or fully understood through the use of animal models. Understanding the events that occur at the first stages of development has potential clinical significance for preventing or treating birth defects, infertility and pregnancy loss.

As we know, stem cells can be found in humans, children as well as adults. These stem cells can be found in the blood (the blood stem cell), where they are found in the bone marrow (hence, the "bone marrow transplant"). In this capacity, the function of blood stem cells is to continuously refill the body's supply of red blood cells, platelets, and white blood cells. Without the blood stem cells in the marrow, the human body cannot survive.

Another main source of stem cells is found in the umbilical cord. So called "cord blood" is an incredibly rich source of the types of stem cells that make up the blood as well as the immune system. These cells can differentiate into blood cells (red, white, platelets), so successfully that some patients with Leukemia, Sickle Cell Anemia, and non-Hodgkin's lymphoma, have been completely cured. In addition, many scientists believe that the stem cells harvested from the umbilical cord could have a tremendous impact on the research and treatment of diseases and disorders such as Alzheimer's, cancer, and many brain disorders (particularly pediatric).

The problem with umbilical cord stem cells, however, is the small amount that can be harvested from any particular cord. Because this is the case, the use of these cells for transplants is normally reserved for pediatric patients or very small adults. However, there are emerging new methods by which these stem cells can be expanded. For example, the American Society of Hematology has discovered a way to expand cord blood cells, and has proven that these cells are every bit as successful as non-expanded cord blood cells. Not only is this development good for those in desperate need of transplantation, but because cord blood is harvested without damaging the fetus, the controversy surrounding its use is minimal. ()

It is true that adult stem cells can be used for research. These cells are found throughout the human body, and they, too, have the capacity to develop into different types of cells--however, they pale in comparison to the ability of embryonic cells to differentiate into specialized cells. As many researches believe, adult stem cells are more "rigid" in their ability to grow and replicate. However, there is promising research that these cells can be successfully harvested and used.

As previously stated, the controversy surrounding stem cell research is primarily due to the use of embryos. Not only could using cord blood and adult stem cells end the moral outcry, but in expanding the amount of cells, many with immune and blood disorders could be helped. However, there is another side to the coin--for just as there are millions against the use of embryonic stem cells for research and development, so, too are there millions in favor of their use due to their tremendous potential.

It is true that embryonic stem cells are superior