4-minute read
In our last blog post, we introduced basic concepts of the electrome. Building on that foundation, we will now delve deeper into bioelectricity, focusing particularly on cell membranes and ion channels.
For you, the reader, to be able to read this text on your computer or mobile device monitor, an almost incomprehensible number of electrons must flow through the providing server, the receiving computer, and the displaying screen. Electrical communication, however, does not end there. Charged particles—ions this time—are equally essential for the sensing eye, the conducting nerve, and the processing brain.
The Cell Membrane
The cell membrane is the outer layer of a cell. It holds the cell together and protects its interior from the environment. This spatial separation is fundamental to the human electrome, as it facilitates voltage. Typically, the inside of a cell is more negatively charged than its surroundings. Positively charged ions are pushed toward the intracellular space but are blocked by the membrane, creating voltage. This voltage is often referred to as membrane potential and is not a passive property; cells actively maintain and regulate this potential, using ion channels.
Ion Channels
Ion channels are specialized proteins embedded in the cell membrane. These channels allow specific ions to pass through the membrane, thereby controlling the membrane potential. Ion channels are highly specific, usually permitting only certain types of ions, such as sodium (Na⁺), potassium (K⁺), calcium (Ca²⁺), or chloride (Cl⁻), to pass. They can be activated by changes in voltage or the binding of ligands (signal molecules). When a channel opens, the corresponding ions follow the electrochemical gradient created by the unequal distribution of ions inside and outside the cell. This ion flow alters the membrane potential, which in turn can influence the cell’s function.1
Nerve Conduction
When ion channels control membrane potential, and membrane potential, in turn, regulates ion channels, feedback loops are created. A small voltage change opens some ion channels; incoming ions cause a larger voltage change, opening more ion channels. Such feedback loops are key in the best-known example of bioelectricity: the nervous system. The membrane potential of a resting nerve cell is about -70 mV but rapidly spikes to +100 mV upon the arrival of an action potential. Shortly after, following a refractory period, the membrane potential returns to normal, and the nerve cell is ready for the next signal. These rapid changes in membrane potential are the fundamental principle behind nerve conduction.2
The Electrical Fingerprint
Advancements in microbiology have revealed that all cells, even those that do not conduct signals, possess ion channels. Further research has shown that signal conduction is just one of many roles the membrane potential plays. Particularly intriguing is the relationship between membrane potential, cell characteristics, and cell growth. Different cell types have distinct resting membrane potentials, which can be considered their electrical fingerprint. For example, nerve cells have a membrane potential of about -70 mV, similar to that of skin cells. Muscle cells are more polarized at -90 mV, while fat cells are less so, at -50 mV. Embryonic stem cells, which multiply during the early stages of human development, have an almost neutral membrane potential. As they develop into “adult” cells, their membrane potential changes, and their proliferation slows. Generally, there is a strong correlation between membrane potential and cell growth, with depolarized cells multiplying more than polarized ones.
These findings are particularly valuable in cancer research. Cancer cells, in simple terms, are like the evil siblings of stem cells. While stem cells multiply and then develop into polarized tissue cells, cancer cells do the opposite. Healthy cells depolarize as they become cancerous, abandoning their original function and beginning to multiply rapidly again. This insight is already playing a significant role in cancer diagnosis and treatment research.3
Cellectric’s research
Understanding membrane potential as an electrical fingerprint which distinguishes cells is central to Cellectric’s research. We are confident that this approach offers numerous opportunities in medicine. Our current project to dramatically accelerate sepsis diagnosis is just the beginning of what selective cell manipulation will be capable of.
Understanding the electrical currents in our bodies and decoding the electrome is one of the biggest challenges in biology. Just as we have, however, managed to create a worldwide network of interconnected streams of electrons, initiating the information age, we will be able to map the electrical currents flowing through our own bodies.
Author: Jonas Palus
1: Chung, S.-H., Andersen, O. S., & Krishnamurthy, V. (Eds.). (2007). Biological Membrane Ion Channels: Dynamics, Structure, and Applications. Springer.
2: Abdul Kadir, L., Stacey, M., & Barrett-Jolley, R. (2018). Emerging roles of the membrane potential: Action beyond the action potential (pp. 1, 5). Frontiers in Physiology, 9, 1661.
3: Adee, S. (2023). We Are Electric: Inside the 200-Year Hunt for Our Body’s Bioelectric Code, and What the Future Holds (pp. 86-87). Hachette Books.