Understanding Telomerase-Positive Pluripotent Stem Cells: Why Aren't They Cancerous?

Since stem cells are already expressors of telomerase, one might wonder how telomerase-positive pluripotent stem cells can avoid becoming cancerous. This article aims to clarify the mechanisms and safety measures in place to prevent the formation of cancer when working with these cells.

Introduction to Telomerase-Positive Stem Cells

Not all stem cells express telomerase, a protein that adds repetitive DNA sequences to the ends of chromosomes, thus lengthening the telomeres. Only certain types of endogenous stem cells exhibit telomerase activity and include totipotent, pluripotent, ectodermal, mesodermal, and endodermal cells, which make up less than 10% of all stem cells in the body. The remaining 40% are telomerase-negative.

Telomerase-Positive Pluripotent Stem Cells

The other category of telomerase-positive pluripotent stem cells are induced pluripotent stem cells (iPSCs), which are derived from differentiated cells through the transfection of genes such as SOX-2, Oct-3/4, Klf4, and c-Myc, referred to as the Yamanaka factors. These cells retain the potential to differentiate into any cell type in the body.

The Lifespan and Differentiation of Telomerase-Positive Stem Cells

When endogenous telomerase-positive stem cells commit to becoming progenitor stem cells for specific cell types, they lose their telomerase enzyme and conform to the biological clock of humans, which limits the number of population doublings to approximately 70. Post-doubling, these cells differentiate in a predefined manner, ensuring they take on a specific function and remain safe and functional.

Induced Pluripotent Stem Cells (iPSCs)

Induced pluripotent stem cells (iPSCs), when used improperly, can become cancerous or form teratomas if transplanted into an undifferentiated state into the tissue. Teratomas are tumors composed of several different tissue types and can form when iPSCs are placed in an environment that does not prompt their proper differentiation. To prevent this, researchers adhere to strict protocols to differentiate iPSCs before clinical or experimental use. This is crucial to ensure that the cells safely integrate into the host’s body and do not revert to a cancerous state.

Conclusion: Ensuring Safety in Stem Cell Research

The control and proper use of telomerase-positive pluripotent stem cells, including their differentiation into specific cell types and the strict protocols governing the use of iPSCs, are essential for preventing the formation of cancer. Research in this area continues to advance, ensuring that these cells can be harnessed for beneficial purposes without increasing the risk of cancer formation.

Understanding the dynamics of telomerase activity and pluripotency is crucial for the safe and effective application of stem cell therapy. By ensuring that these cells are carefully controlled and differentiated, we can overcome the risks associated with elusive cancerous transformation.

Keywords: telomerase, pluripotent stem cells, cancerous cells, stem cell research, telomerase-activity