Yuka Sakuma, associate professor of the Graduate School of Science, has been the principal investigator of a pioneering study. Her published work shows living cell membranes to be orders of magnitude more viscous than modeled artificial systems. She and her colleagues flushed out a new, groundbreaking idea that biological structures can have different viscosities. Specifically, they highlighted how important short-range and long-range viscosity were for the functionality of living cells. This research was published in the Biophysical Journal on September 19, 2025, under the title “Hidden resistance in cell membranes: Discovery of long-range membrane viscosity.”
The unexpected findings, researchers say, are a huge step toward understanding how biological cells control the elasticity of their membranes. The researchers discovered that conventional models simply cannot replicate the viscosity found in living cells. These models frequently fail to consider the nuances found in biological systems.
Understanding Viscosity in Living Cells
Sakuma’s research introduces two distinct types of viscosity that characterize living cells: short-range viscosity and long-range viscosity. Short-range viscosity is related to the molecular thermal motion and determines how single molecules in the cell membrane behave. This third type of viscosity is arguably the most important for determining local dynamics and behaviors at the microscopic level.
Long-range viscosity is dictated by cell-scale structures and interactions, which determine how the membranes move overall. This surprising idea illuminates more broadly how the structure of cell membranes plays an essential role in their many diverse functions. Sakuma and her colleagues make an important distinction between two forms of viscosity. This methodology provides us a more mechanistic basis for dissecting the cell mechanical qualities of membranes.
The implications of this research are profound. With a clearer understanding of viscosity dynamics, scientists can better explore cellular processes such as signal transduction, membrane fusion, and the movement of proteins within the membrane.
Implications for Biological Research
As Sakuma et al. recently reported, these are tragic but all too common findings. These findings promise to be rich new sources of inquiry into cellular mechanics and membrane biology. By establishing that living cell membranes have higher viscosity than model systems, they challenge existing paradigms that may overlook essential factors influencing cellular behavior.
In addition to creating novel tools for biophysics, Sakuma’s work demonstrates potential biomedical applications. Enhanced knowledge about membrane viscosity could inform drug delivery systems, tissue engineering, and even the development of treatments for diseases linked to membrane dysfunction.
Beyond Sakuma’s observations, she and her team produced important theoretical contributions. They went a step further and developed comprehensive conceptual diagrams that map out short-range and long-range viscosity mechanisms. These helpful visualizations are an indispensable tool to researchers. They provide support for researchers who want to explore the mysteries of cell membranes.
Future Directions in Cell Membrane Research
Now that this study is making waves in the scientific community, it begs the question – what’s next? Thus, there is a documented necessity to more deeply investigate how distinct cellular microenvironments could affect viscosity parameters. Future research will be needed to investigate other cell types. To answer this question, they may combine new imaging technologies to track viscosity processes in real time.
Sakuma’s research illustrates the need to look beyond purely molecular-level interactions and examine larger structural effects when investigating biological systems. This dual approach to understanding viscosity creates an exciting avenue for interdisciplinary collaboration among physicists, biologists, and medical researchers.