Proliferation or Differentiation Potential
Differentiation and Proliferation Assays as a Measure of Stem Cell Potency
Differentiation is defined as the process whereby undifferentiated cells acquire the features of specialized cells.
Proliferation is defined as the expansion of cells by the continuous division of single cells into two identical daughter cells.
The relationship between proliferation and differentiation is:
- Proliferation occurs before differentiation.
- Without proliferation, differentiation would not occur.
- Differentiation is a default program requiring prior proliferation.
Stem cells are, by definition, undifferentiated cells (see Stem Cells and the Blood-Forming System). The colony-forming cell assay is therefore NOT a proliferation assay, but rather a differentiation assay, since the end result of a colony-forming cell assay is the production of colonies containing functionally mature cells by which the colony can be identified under the microscope. Therefore, assessing the differentiation capability of cells as detected in the colony-forming cell assay, is secondary to their ability to initiate and sustain proliferation.
