Stem cells are unique cells, they are the cells from which all other cells originate.
Each type of cell and tissue has their own stem cells which are responsible for creating and replacing those cells and tissues. Our stem cells live in niches within the tissues they repair or replace.
Stem cells are dormant most of the time (a state called ‘quiescence’), waking up only when we need them to produce the cells they specialize in. To give you an idea of how special these cells are there are roughly 1 stem cell for every 6 million cells in our body.
Stem cells receive their instructions from the DNA in their genes. Cancerous mutations occur within this DNA and affect the genes that are involved in repairing damaged DNA. The result of this damage is that our cells stop functioning the way they are supposed to, which can cause a tumour to develop. A tumour usually develops a short distance away from the stem cell niche where the DNA damage occurred.
All of this protein (a general term for the product of a gene) creation is happening inside our cells. Once the protein structures are created they are released by the cells and begin to fulfil their role in our body.
While all of our cells contain DNA it is only mutations within the DNA of our stem cells which lead to cancer.
To understand how mutations occur we need to understand how our stem cells replicate. Stem cell process involves two stages
Proliferation means the stem cell makes an exact copy of itself. Proliferation creates another stem cell which lays dormant in the stem cell niche until it’s needed.
Differentiation happens when the copied stem cells are converted into a normal cell (the type of cell it’s destined to be), it is then given a Hayflick number - the number of times the normal cell will divide and replicate before it stops and dies. This is a process called ‘pre-programed cell death’. Cell death is a completely normal process and something predetermined when new cells are created. Programmed cell death allows the body to recycle its products.