‘Stem cell research can revolutionize medicine, more than anything since antibiotics.’
These are the words of 40th US President, Ronald Raegan. But what are stem cells, and why did Raegan see them as a revolutionary device in modern medicine?
Our bodies are made up of millions of cells, each one with a designated task. But before they differentiate, they exist as stem cells. There are three main types of stem cell, which behave slightly differently when becoming specialised.
The first of these main types is embryonic stem cells. This type of stem cell is the foundation of human development; they appear in early embryos (blastocysts), around 5 days after the egg cell begins to divide. Embryonic stem cells are pluripotent, meaning they can differentiate to become any kind of cell we find in the human body. Brain, liver, hair, muscle. You name it, an embryonic cell can differentiate to become it.
The second sort of stem cell, however, behaves slightly differently. Adult stem cells, which are the other main sort, are vital in cell regeneration. Unlike embryonic stem cells, adult stem cells do not possess a pluripotent nature. Instead, they are known as multipotent, allowing them to become specialised based on the organ in which they are found, although this supply is limited.
The final category, induced pluripotent stem cells, are essentially specialised cells that have been ‘reprogrammed’ to behave like embryonic stem cells. These cells were developed after groundbreaking research in the field of stem cells discovered that adult specialised cells could be manipulated to behave like embryonic stem cells. However, the process to reprogram this type of stem cell is yet to be fully understood, so its use in cell therapy is still theoretical.
Adult stem cells are most commonly used in blood transplants. These may be necessary to treat certain diseases and conditions of the blood and immune system, or to restore the blood system after treatment of specific cancers. These transplants require a donor with the same blood type; often this a sibling, parent or close relative, although not always. Since the transplants come from someone who does not necessarily have the same genetic makeup as the patient, there is a risk of rejection from the immune system. To combat this, cord blood banking can be done at birth, leaving the patient with a rich supply of blood stem cells. This can be used as treatment for children suffering from certain cancers, e.g. leukaemia. However, the quantity of cord blood obtained from an umbilical cord isn’t enough to treat adults. As a result of this, double the quantity is needed, meaning that the cord blood has to be matched to the patient to minimise risk of rejection. Adult skin cells are also used for skin grafts, to treat severe burns, very large burns, or both. However, the skin grafts are usually reserved for life threatening burns.
On the other hand, embryonic stem cells have potentially endless possibilities for cell therapy. However, there are ethical considerations, since these stem cells are primarily obtained from blastocysts. Some scientists and religious people question when human life truly begins, and whether it is morally right to produce embryos that will be destroyed in a matter of days. Furthermore, since these cells have to be formed in a laboratory, there is also a risk of viral transmissions and infections.
All in all, stem cells have the potential to be used in a plethora of life-changing treatments. However, the knowledge on this vast and diverse field is not fully developed, and new things are still being discovered. Fundamentally, stem cells have the power to revolutionise modern medicine.