Stem Cells: Self-Renewal and Potency

Stem cells are a type of biological cell that have the ability to differentiate into exponentially more cells of any cell type and are only found in multicellular organisms. Stem cells have two main properties: self-renewal and potency.

Self-Renewal

Self-renewal is the ability to go through multiple cycles of cell division while maintaining the undifferentiated state. Each stem cell goes through one of two processes to assure the undifferentiated trait is maintained throughout each cycle of cell division.

Obligatory Asymmetric Replication

One of these processes is known as obligatory asymmetric replication. This is when a stem cell divides into two daughter cells. One of these cells is an exact copy of the original stem cell, while the other is fully differentiated. The exact copy also has the same potency as the original stem cell (keep reading to find out what potencies are)!

Stochastic Differentiation

The other possible process is known as stochastic differentiation. This is when one stem cell develops into two differentiated daughter cells, while another stem cell goes through the process of mitosis and produces two diploid daughter cells identical to the original stem cell.

Potency

Potency is the differentiation potential (the ability for a stem cell to differentiate into many cell types). Stem cells have one of five potencies:

Totipotent (omnipotent) stem cells are embryonic cells that are created within the first few rounds of cell division after fertilization. Since these cells can differentiate into all of the cell types, as well as the extraembryonic cell types (which play roles in the development of the embryo but do not become part of the organism after birth), totipotent stem cells can build up a complex, multicellular organism. An example of a totipotent cell is a zygote, which is formed when sperm fertilizes an egg).

Pluripotent stem cells are the daughter cells of totipotent cells from multiple cycles of cell division (you could call them descendants of totipotent cells). These cells can differentiate into almost every cell type (from any of the three germ layers: endoderm, mesoderm and ectoderm). An example of a pluripotent cell is an iPSC or induced pluripotent stem cell (Click Here to read my previous article about these specific cells).

Multipotent stem cells can differentiate into a limited number of cell types, usually those that fall into a specific range of cell types. Such cell types share some similarities and some differences, making them diverse to an extent. An example of a multipotent cell is the mesenchymal stem cell, which can differentiate into bone, muscle, fat and cartilage cells.

Oligopotent stem cells are even more restricted in terms of differentiation potential than multipotent cells. The number of cell types they can differentiate into is very small. An example is the hematopoietic stem cell. Hematopoietic stem cells come from the mesoderm (second germ layer) and can only differentiate into other blood cells.

Finally, unipotent stem cells are only able to differentiate into one cell type. An example of unipotent cells is a muscle cell as it only differentiates into other muscle cells.

Key Takeaways:

• Stem cells are cells that have the ability to differentiate into any other cell
• Stem cells are identified by their two properties: self-renewal and potency
• Self-Renewal is the ability to go through multiple cycles of cell division, while maintaining an undifferentiated state.
• Potency is the ability of a stem cell to differentiate into a certain amount of cell types
• Stem cells’ potencies are classified as one of the following (from greatest potency to least potency): totipotent, pluripotent, multipotent, oligopotent, unipotent

“Stem cell research has the potential to alleviate so much suffering. Surely, by working together we can harness its life-giving potential.”

Thank you for reading and stay tuned for my upcoming article: The Prospect of Nanotechnology in the Genomics Field!