Stem cells – they are in the news and have been for a few years now – this shouldn’t be a surprise because they offer the hope of a cure to currently incurable medical conditions such as Parkinson’s disease and spinal injuries. Also sufferers of diseases as common as diabetes may benefit. In the future lies the hope of producing organs that will not be rejected by the immune system of people who need a transplant.
So what is the principle behind this possible great leap forward in medical science?
First of all you need to understand the fact that all the cells in the body have the same DNA in their nucleus. The DNA is a set of instructions that allows the cell to perform its function. However cells are specialised in the body – certain types of cells do certain types of jobs and produce certain types of chemicals. For example, the alpha cells in the Islets of Langerhan in the pancreas produce the hormone insulin that helps to regulate our blood sugar level.
Specialisation of cells is a result of the cell using a particular set of genes in the DNA within its nucleus. So, an alpha cell will use certain genes that a liver cell will not use and vice-versa. A cell uses about 15% of its DNA in total.
Stem cells are cells that have not yet specialised (Biologists usually use the term ‘differentiated’). They are found in certain places in the human adult – such as the bone marrow – but this type of stem cell is restricted in terms of what kind of cell it may become e.g it may only be able to become a certain type of blood cell.
Of most interest to medicine are the stem cells found in embryos because these stem cells can potentially become any type of body cell: a nerve cell, an alpha cell, a liver cell etc. If scientists can unlock the secret of how these cells specialise then they will be able to make them become any kind of cell they like – and potentially will be able to create any tissue and ultimately any organ.
Using human embryos cloned from the adult sufferer of an illness such as diabetes – scientists may be able to make alpha cells that are identical to the existing body cells in terms of their DNA – and therefore will be able to transplant this tissue into the adult (in this case into the pancreas) without the risk of rejection of the tissue that is currently such a problem in transplantation.
The potential is staggering. Parkinson patients could be given new nerve cells to replace those that have degenerated, new heart tissue for those who have had a cardiac arrest etc. Also nerve implants for spinal injury sufferers are a real possibility.
So, apart from the ethical implications, which are not in the scope of the article, stem cell research may offer a cure to people suffering from these currently incurable diseases and conditions.