The ability of a stem cell to divide and produce copies of itself for an indefinite period of time. This is the defining property of stem cells. Such stem cells have been described as "eternal" in the sense that they can continue growing indefinitely if kept in the right conditions.
Sickle cell anaemia is an inherited blood disorder where the red blood cells, which carry oxygen around the body, develop abnormally. Red blood cells in sickle cell anaemia are can become rigid and shaped like a crescent (or sickle). The sickle-shaped cells contain defective haemoglobin and can also block vessels, causing tissue and organ damage.
Stem cells are found throughout our bodies and help us replenish cells that cells that have been used up or damaged. They are able to replicate and produce copies of themselves – daughter cells – as well as possessing the ability to differentiate into more specialised cells for different cell types each time they divide.