By Riya Gandhi ‘22

Human cells multiply at high speeds to maintain proper functioning of the human body. Even when occur and cancerous growths appear, the cell cycle does not cease; as a result, the number of malignant cells rapidly increases. One aspect in the chemistry of cell proliferation is clear: monovalent ions contribute to the cell cycle. The specifics of their role, however, are not yet well-understood. Under the guidance of head investigator Irina Marakhova, researchers at the Academy of Sciences in St. Petersburg, Russia, were able to uncover the involvement of the potassium ion in the regulation of cell proliferation.

In the experiment, researchers initially evaluated K+ and Na+ contents in a culture of human mesenchymal stem cells (hMSC). These stem cells are born and develop in embryonic connective tissues, such as bone marrow, and are capable of renewing and differentiating themselves. At the onset of the procedure, the hMSCs grew exponentially as expected. When Marakhova and her colleagues normalized the ion concentrations in each cell, they discovered that the potassium ion content of the hMSCs changed throughout the process of cell growth. What was even more intriguing to them was that after this initial increase, K+ content subsequently decreased. On the other hand, the Na+ content did not nearly shift as much. To determine if the shift in K+ content was caused by hMSC growth over an extended period of time, the researchers prepared two cultures with different cell densities; they concluded that higher cell densities led to lower K+ content. Moreover, after analyzing the cell cycle and utilizing a stress-induced cell cycle, the team found that a rise in G1 cells corresponded with a decline in K+ content. These findings led the researchers to propose that potassium ions are necessary for successful cell proliferation and are responsible for regulating cell volume.

This discovery potentially provides researchers with a physical marker in stem cell proliferation, which may allow them to better assess the functionality of stem cells. In the future, this physical marker may prove useful in tracking and eliminating cancer stem cells.

References

1. I. Marakhova, et. al., Proliferation-related changes in K+ content in human mesenchymal stem cells. Scientific Reports 9, (2019). doi: 10.1038/s41598-018-36922-y.  
2. Image retrieved from: https://www.pexels.com/photo/background-binoculars-black-blue-267596/