What are Stem Cells?
Stem cells are constantly in the news these days. Their use is being restricted. Stem cell research needs more funding. Stem cells may help cure a long list of diseases. But just what are stem cells and where can you find them?
Defining the Stem Cell
Everybody has stem cells; they are what make up our bodies. In fact, they are what our organs and cells are before they become, well, organs and cells. What separates a stem cell from other cells in your body is the fact that they are unspecialized. This means that they have not developed into any particular cell just yet. Under specific physiological conditions, however, stem cells begin to mature and develop into cells with special functions.
This process, known as differentiation, can also be induced artificially and this is the technology that scientists are trying to master in their stem cell research. By learning how to effectively induce and control differentiation, scientists will be able to turn unspecialized stem cells into other cells, like heart muscle cells or blood cells.
Additionally, stem cells have the ability to renew themselves many times over, a process known as proliferation. When they continue to renew themselves as unspecialized cells, the stem cells are thought to be proficient in self-renewal for a long period of time.
Sources of Stem Cells
Stem cells can be found in different places. And just where you get your stem cells from can make all the difference as to their potential.
1. Embryonic Stem Cells: Using a donated human embryo, scientists are able to extract the blastocyst (inner cell) from the 4-day old embryo. This is then cultured for about six months in a Petri dish until a ‘cell line,’ which contains millions of stem cells, is produced. Embryos are usually obtained from a donor who has given their informed consent that their embryos, originally created for IVF but are now no longer needed, may be used for stem cell research. These embryonic stem cells are thought to hold the most potential as they are primitive and can develop into any other cell in the body.
2. Bone Marrow: Bone marrow is the spongy material you find inside your bones. Contained within bone marrow, however, are stem cells. In fact, aside from cord blood, bone marrow is the richest source of adult stem cells. However, bone marrow stem cells have matured and therefore are more restricted as to what type of cells they can differentiate into. Moreover, normal environmental exposures and toxins have likely affected these cells. As a result, their use is more limited. Bone marrow transplants have been used to treat blood disorders, immune system disorders and genetic disorders.
3. Peripheral Blood Stem Cells: These stem cells also fall into the category of adult stem cells. Peripheral blood refers to the blood circulating in your system. Although this isn’t the richest source of stem cells, peripheral blood stem cell donors can be administered ‘growth factor’ drugs to help increase their number of stem cells. When donating the stem cells, blood is withdrawn from the body and stem cells are separated from the blood before the blood returns to the body. While this method of donation is simpler than bone marrow donation, there is a greater chance that the recipient will have complications, like graft vs. host disease.
4. Cord Blood Stem Cells: Like embryonic stem cells, cord blood stem cells hold great potential in treating a wide number of diseases and disorders. However, they can be obtained without causing controversy, which makes them a much greater resource. Additionally, although they are classified as ‘adult stem cells,’ cord blood stem cells are actually much more primitive than bone marrow or peripheral stem cells. These stem cells are taken form umbilical cord blood shortly after birth; once the umbilical cord has been cut, a nurse or doctor can drain the blood from the cord. This blood can then be frozen and stored privately or donated to public cord blood banks. When it is needed, the stem cells are thawed and ready to use in stem cell therapy. Currently, there are over 70 diseases and disorders cord blood stem cells can treat, with more being added to the list all the time.
Which is Best?
It is difficult to say that one source of stem cells is better than another; all have their benefits and drawbacks. For instance, bone marrow has been used successfully in stem cell treatments for many years now. However, it can be difficult to find a perfect matching donor in an appropriate amount of time. As well, giving bone marrow can be painful. Furthermore, because bone marrow stem cells are more developed, their potential for use is limited.
Embryonic stem cells have the ability to become almost any other type of cell in the body and therefore are capable of treating an incredible range of issues. From Parkinson’s disease to heart defects; from Alzheimer’s to baldness, it is thought that embryonic stem cells may be able to help. Yet, because they come from embryos, many people do not feel comfortable with this technology. The question of whether to use stem cells derived from embryos is surrounded by controversy making it very difficult to move forward with research in this area.
Many are hailing cord blood stem cells as the next best thing. Because they are primitive, these stem cells can treat many different disorders, although their ability is not as vast as embryonic stem cells. While it is very easy to collect stem cells, parents only have one chance to do it – when their child is born. Additionally, the amount of stem cells collected from cord blood is not as great as from other sources. However, a handful of treatments have been performed using stem cells from two separate cord blood sources with successful results.
Unlike bone marrow transplants, which require a perfect match between donor and recipient, people receiving a cord blood stem cell transplant do not need to be as perfectly matched on Human Leukocyte Antigens (HLA) for the transplant to be successful. This means that more people can benefit from these stem cells. Finally, because cord blood stem cells are collected and stored in cord blood banks, they are readily available to be used when you need it; you do not need to wait months for a proper donor to be found as with bone marrow transplants.