After my most recent post on multiple sclerosis in which I discovered that stem cells have the ability to prevent the MS from progressing any further, I decided to look into stem cells a bit more in order to gain a better understanding of what they are, and how they can benefit medicine in the future.
What are stem cells?
Stem cells are found in multicellular organisms, and they have the ability to differentiate and become specialised. In addition, they can also undergo mitosis to produce more stem cells. There are two main types: embryonic and adult (somatic) stem cells.
Where do they come from?
Embryonic stem cells – these cells come from the embryo when it is only 4-5 days old, meaning it contains only 100-150 cells at this point. At this stage, the embryo is known as a blastocyst, and consists of an outer layer of cells (trophectoderm), and an inner mass of cells which are undifferentiated.
Adult stem cells – such cells can be found throughout the body, and will remain in a quiescent (inactive) state until activated by disease or damage to tissue. Whilst most commonly found in the bone marrow, these stem cells can also be found in tissues such as the brain, the blood, the skin and the liver.
Stem cells now have a huge number of uses, given that scientists have figured out how to successfully remove them and encourage them to differentiate into all kinds of cells to treat all kinds of diseases and illness through growing new tissues or even entirely new organs (for example a trachea to replace one that had been blocked by a tumour).
Multiple sclerosis – multiple sclerosis is a degenerative disease caused by a fault in the immune system which causes it to attack nerve cells, damaging or destroying the myelin that coats them. However, scientists have managed to create a therapy which can prevent the MS from progressing any further (although it is unable to reverse damage already done). It is known as autologous haematopoietic stem cell transplant, and involves using chemotherapy to destroy the old immune system, and then using the patient’s own stem cells to produce a new one.
Whilst this remains a relatively new therapy, so far it has been a great success, and extensive research has shown that there are no long term effects and that MS does not return.
Treating burns victims – patients who have suffered extensive burning may be able to improve healing of the wound, reduce the formation of scarring and potentially even restore sense of touch in skin through use of stem cells. There is a large source of stem cells located just below the skin, which can be taken from a healthy area on the body and grafted on to the damaged area to engineer new skin tissue. The severity of the burn and how deep down the cells affected are depends on how much function of the skin can be restored.
Cancer – given that cancer is caused by the abnormal division and cell differentiation of cells, studying stem cells will give a better understanding of what causes a cell to differentiate and the signals it receives a releases during this process. In the future, this could allow scientists to learn what triggers tumours to form, how to stop them, and potentially how to identify cells which could cause tumours in the future.
Stem cells are also being used to treat cancers such as leukaemia, in which high doses of chemotherapy may destroy not only a cancerous tumour but also the healthy stem cells in the bone marrow. Doctors can harvest healthy stem cells from the patient or a donor and then put into a vein after a high dose treatment to replace the ones lost.
Whilst the use of adult or somatic stem cells is generally considered to be ethically acceptable, there remains a great deal of controversy over the use of embryonic stem cells. This is because it involves creating multiple embryos to then destroy them, and many people are against this because they view it as killing an unborn child. However, others argue that because the embryo cannot feel anything and is not truly a child yet, that it is morally acceptable to use stem cells taken from an embryo.
There is an additional argument similar to the concept of ‘lesser of two evils’, in which people argue that whilst it may kill an embryo, it could save the life of someone who already has been born, although this is also a controversial argument in itself, as some say that it is immoral to value the life of one person over another.
In Japan, 2006, scientists managed to create their own embryonic stem cells, called induced pluripotent stem cells or iPCS and this could solve the ethical problem as no embryo loses its life in their creation. Despite this however, some scientists argue that iPCS are not quite the same as embryonic stem cells, and consequently, cannot yet be used in place of embryonic stem cells.
Thanks for reading!