In short
Stem cells are unspecialised cells with two defining properties: self-renewal, dividing to maintain their own population, and differentiation, becoming other cell types. In medicine they are studied to understand tissue repair and inflammation.
Core properties
Stem cells self-renew and can differentiate into specialised cells. Mesenchymal stem cells also secrete large numbers of signalling molecules, a mechanism many researchers consider more important than direct conversion into new tissue.
Main types in research
Embryonic stem cells have the greatest potential but carry ethical and safety considerations. Induced pluripotent stem cells (iPSC) are reprogrammed from adult cells for in-depth research. Adult stem cells such as MSC are the most widely used in clinical research.
What stem cells are not
Stem cells are not a universal treatment, not a guarantee of recovery, and not the same as supplements or cosmetics advertised as containing stem cells — most of which contain no living cells.