There are few controversies that polarize individuals as does the one surrounding stem cell research. I will attempt to take a very difficult subject and educate readers about it.
The human body is made of approximately 220 different types of cells. Each is the foundation for the development of all of our tissues and organs. Once these different cells develop into specific tissues and organs, we have an embryo.
A stem cell is essentially the building block of the human body. The stem cells inside an embryo will eventually give rise to every cell, organ and tissue in the fetus’ body. Unlike a regular cell, which can only replicate to create more of its own kind of cell, a stem cell has the capability of reproducing itself many times over.
There are two types of stem cells: embryonic stem cells and adult stem cells. Embryonic stem cells come from an embryo. When the embryo is between three and five days old, it contains stem cells, which work to create the various organs and tissues that will make up the fetus.
Adults have stem cells also. These cells are located in the heart, brain, bone marrow, lungs and some other organs. They are regenerating cells damaged by disease, injury and everyday wear and tear.
Scientists remove stem cells from the embryo and grow them in a nutrient-rich solution in the laboratory. This growth and re-implantation of these cells continues until, in just a few months, several stem cells can become millions of stem cells. Embryonic stem cells can then be frozen and used at a different time. Although I have made this sound simple, the process is very difficult and time consuming.
As difficult as embryonic stem cells are to work with, adult stem cells are much more difficult for scientists to develop. Stem cells are not only harder to find in adult tissue, but scientists also have difficulty getting them to replicate in the laboratory. Embryonic and adult stem cells are hard for scientists to grow into specific tissue types.
If scientists can ultimately learn how to direct stem cells to become different cells and thus form different types of tissue, they can use them to replace diseased tissue. This has not happened because scientists still haven’t learned how to have the stem cells become a specific tissue or cell type (heart vs. brain, for example).
A real issue that stands in the way of stem cell use is the problem of rejection. If a person is injected with stem cells taken from a donated embryo, his or her immune system may see the cells as foreign invaders and launch an attack against them.
Eventually, scientists would like to be able to grow entire organs in a laboratory to replace ones that have been damaged by disease. Based on this theory, a biodegradable reproduction of the organ would be implanted or attached to the individual and the organ specific stem cells would seed the new organ. As the tissue grew from the stem cells, the implanted or attached part would degrade, leaving a complete ear, liver or other organ.
Some of the conditions that may one day be treated with cell-based therapy are: Parkinson’s disease, diabetes, heart disease, spinal cord injury, burns, Alzheimer’s disease and vision loss.
Stem cell research has become one of the biggest issues dividing the scientific and religious communities around the world. At the core of the issue is one central question: When does life begin?
Even as scientists move forward in their understanding of stem cells and their ability to manipulate them, the ethical and political debates rage on. As would be expected, stem cell research is extremely expensive, and thus many governments have placed tight restrictions on it.
Stem cell research is controversial because in order to get stem cells, scientists either have to use an embryo that has already been conceived or clone an embryo using a cell from a patient’s body and a donated egg. Either way, to harvest an embryo’s stem cells, scientists must destroy it. Some individuals say that destroying it is the equivalent of taking a human life, though it may only have four or five cells.
Also at issue is the idea of cloning. Cloning is the process of making a genetically identical organism through nonsexual means. The idea of human cloning brings to mind frightening scenarios of babies genetically engineered to be “super humans” with top IQs and super-hero-like physical capabilities, or babies created solely for the purpose of harvesting their organs.
Cloning has been used for many years to produce plants (even growing a plant from a cutting is a type of cloning). In 1997, animal cloning garnered a lot of attention with the birth of the first cloned mammal, a sheep named Dolly. Since Dolly, several scientists have cloned other animals, including cows and mice.
The recent success in cloning animals has sparked fierce debates among scientists, politicians and the general public about the use and morality of cloning plants, animals and possibly humans.
To bridge the debate, scientists are exploring less controversial avenues of research, using adult stem cells that are trained to act like embryonic stem cells. Even if the outcome of the debate favors the use of stem cells, it will likely be at least a few more decades until stem cell therapies come into widespread use.
Dr. Van Stitt Jr. is vice president and chief medical officer of Gaston Memorial Hospital.