Potency is the ability or potential of stem cells to differentiate into other types of cells.
Table 1.1 below lists the full classification of stem cell potency:
|Unipotent||Only produce cells of their own type, have self-renewal property with the help of stem cells||Muscle stem cells|
|Oligopotent||Differentiate into a few types||Lympholid or myeloid stem cells|
|Multipotent||Differentiate into a closely related family of cells||Hematopoietic (audlt) stem cells that become red and white blood cells or platelets|
|Pluripotent||Differentiate into almost all cell types||Embryonic stem cells: cells derived from the mesoderm, endoderm and ectoderm germ layers during blastocyst development|
|Totipotent||Differentiate into all possible cell types||Zygote formed at egg fertilization and first few cells resulting from zygote division|
Embryonic stem cells are one of the most potent cell types, as they have the potential to become any type of cell in the body, except extra-embryonic membranes or the placenta. Therefore, embryonic stem cells are considered to be pluripotent.
Stem cells give rise to specialized cells in different stages. The intermediate cell types are known as committed progenitors (Figure 1.2). They are not fully differentiated cells but have different properties from stem cells. These cells divide many times to produce fully differentiated and functional cells through different steps. Figure 1.2 shows the different steps.
This hierarchy can be applied to many types of tissue specific stem cells. One example of the process of differentiation is the hematopoietic stem cells and mesenchymal stem cells. These cells give rise to all the types of blood cells and bone cells.
A stem cell divides into two daughter cells: one is an undifferentiated stem cell and the other one is a committed progenitor. The progenitors are the intermediate cells between stem cells and specialized cells, which are multipotent and divide rapidly. These cells become more specialized by each cell division. Finally, the working cells, also called the specialized cells, are formed. There is no further cell division once the cells are formed.