What Are Stem Cells? – CSA

Stem cell research has been hailed for the potential to revolutionize the future of medicine with the ability to regenerate damaged and diseased organs. On the other hand, stem cell research has been highly controversial due to the ethical issues concerned with the culture and use of stem cells derived from human embryos. This article presents an overview of what stem cells are, what roles they play in normal processes such as development and cancer, and how stem cells could have the potential to treat incurable diseases. Ethical issues are not the subject of this review.1

In addition to offering unprecedented hope in treating many debilitating diseases, stem cells have advanced our understanding of basic biological processes. This review looks at two major aspects of stem cells:

What are stem cells?

Stem cells are unspecialized cells that have two defining properties: the ability to differentiate into other cells and the ability to self-regenerate.

The ability to differentiate is the potential to develop into other cell types. A totipotent stem cell (e.g. fertilized egg) can develop into all cell types including the embryonic membranes. A pleuripotent stem cell can develop into cells from all three germinal layers (e.g cells from the inner cell mass). Other cells can be oligopotent, bipotent or unipotent depending on their ability to develop into few, two or one other cell type(s).2

Self-regeneration is the ability of stem cells to divide and produce more stem cells. During early development, the cell division is symmetrical i.e. each cell divides to gives rise to daughter cells each with the same potential. Later in development, the cell divides asymmetrically with one of the daughter cells produced also a stem cell and the other a more differentiated cell.

Differentiation Potential

Number of cell types

Example of stem cell

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What Are Stem Cells? - CSA