Stem cells are cells with the potential to develop into many different types of cells in the body during early life and growth. How are they different to other cells? They can divide and renew themselves over a long time, making them useful as a sort of internal repair system; they are unspecialised so they cannot do specific functions but they have the capability to become specialised cells, for example, muscle cells or red blood cells.
In humans, there are different types of stem cells that come from different places in the body or are formed at different times in our lives. There are embryonic stem cells that exist only at the earliest stages of development (in a three to five year old embryo, known as a blastocyst) and there are different types of tissue-specific or adult stem cells that appear during the earliest stages of development and remain in our bodies throughout our life. Embryonic stem cells are pluripotent, which means that they can develop into different types of body cells but cannot generate support structures like the placenta and the umbilical cord. Other cells are multipotent which mean they can develop into a few different cell types, generally in a specific tissue, hence why they are called tissue-specific stem cells.
As humans grow older, the number and type of stem cells change. The stem cells that stay in your body throughout your life are tissue-specific; however, there is evidence that the skin stem cells in your body at a young age won’t be the same as the ones in your body when you are older.
There are also induced pluripotent stem cells (iPS), which are similar to embryonic stem cells, although they are made from specialised adult cells using a laboratory technique discovered in 2006 which won a Nobel Prize. So what are scientists so excited about? The discovery of these stem cells raised hopes that cells could be made from a patient’s own skin to cure their disease, this allows the risk of immune rejection to be removed. The finding of these cells allows cell banks to be created, which allows a matching donor to be found for patients, almost like a blood bank.
In a stem cell transplant, embryonic stem cells are specialised into the appropriate adult cell; they are then used to replace the tissue that has been damaged. This method can be used to replace neurons damaged by spinal cord injury, strokes or other neurological problems; used to produce insulin to treat those with diabetes; replace any tissue or organ that has been injured or diseased and others. Using embryonic stem cell therapies can be much more useful in medical research as cells could be used to study diseases, to create new drugs and to test drugs for side effects