All living organisms are made up of billions upon billions of cells. Each type of cell serves a different function, and every organ is solely constructed of one type of cell. From brain cells to skin cells, they all have one specific task that they are able to perform. These cells all start from the same place however, a blank slate from which they differentiate and morph. These ‘un-programmed’ cells are known as stem cells.
Stem cells in mammals come in two different varieties: embryonic stem cells and adult stem cells. The difference between these types is fairly simple to understand. Adult stem cells can be found in both juvenile and adult mammals and are the means by which the body is able to repair itself. Without them, injuries would not heal, leaving dying cells and tissues no way to be replenished.
The reason that scientific interest exists in these stem cells is their ability to divide indefinitely, producing all the cells needed for an organ to function. This means that potentially, with a small sample of adult stem cells from a liver, scientists could grow an entirely new liver. The medical applications of this process are incredible in their scope and could save millions of lives when the process is more fully understood and developed.
For many years now, adult stem cells have been successfully used in the treatment of a variety of diseases. The most common use has been for the treatment of leukemia and other types of blood and bone cancers through the process of bone marrow transplants. They have also proven effective in the treatment of spinal cord injuries, liver cirrhosis, and several vascular diseases. Unfortunately, stem cell function deteriorates as the cells continue to age. This limits the potential of the possible medical applications of adult stem cells.
Embryonic stem cells on the other hand, are both far more controversial and useful than their adult stem cell counterparts. The controversy is rooted in the source of the embryonic stem cells, and the ethical debate surrounding the harvesting of the cells continues to rage throughout the world. Embryonic stem cells can be harvested from a human embryo four to five days after the fertilization process. The debate is centered around the question of whether or not an embryo at such an early stage of development should be considered a living person. This has obvious parallels to the debate over the morality of abortion. Essentially, when in the process of development does an embryo become a person?
The medical applications of embryonic stem cells are varied and unprecedented in scope. It is believed that these stem cells could be incredibly effective in the treatment of several genetic disorders like Parkinson’s disease and cystic fibrosis, which for many are currently a death sentence. They are also being looked at as a method of treating diabetes or severe heart failure. The most optimistic of these possible applications is in DNA repair; in layman’s terms a cure for the aging process. Until further research is done however, many of these treatments remain entirely hypothetical.