A team of researchers from the Massachusetts Institute of Technology, Massachusetts General Hospital and the University of Maryland have developed an optical microscopy technique that is able to measure mechanical properties of cells and evaluate them in the context of disease progression or wound-healing.
“Over the past 15 or 20 years, there has been a lot of literature that shows that the mechanical properties of a cell is important for basically every cellular function,” said Giuliano Scarcelli, an assistant professor with this university’s Fischell Department of Bioengineering. “Now, you have a way to basically test how are the cells behaving from a mechanical standpoint.”
Scarcelli said recent developments in this research have allowed for higher-resolution microscopy that allows researchers to measure stiffness within a single cell.
The technique — called Brillouin optical cell microscopy — was published in the Nature Methods journal this month and might offer new opportunities for identifying how certain diseases such as cancers develop in the body, as well as how cells change over time through non-invasive methods of measurement.
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Traditional methods of measuring mechanical properties of a cell involve physically touching the cell and seeing how it responds, which is preferable because it is more exact, Scarcelli said.
But with this new method, which creates images, researchers can evaluate the stiffness of cells inside tissues or the body that they might not be able to touch to see what’s going on inside the cell, how it responds to its environment, the stiffness of the tissue surrounding a cell and how cells move and change their shape to squeeze through tissue, said Seok-Hyun Yun, who works for the Wellman Center and is a Harvard Medical School professor.
Using a microscope attached to a very high-resolution spectrometer, researchers are able to shine light into the material. When this is done, a little bit of the light changes color, Scarcelli said, and that changing color is proportional to the elasticity of the model.
“It’s sort of the Holy Grail of cell mechanics: in a non-invasive manner to be able to measure the stiffness or compliance of the cell rapidly and get three-dimensional information about the cell,” said Roger Kamm, a professor of biological and mechanical engineering at MIT whose work with the new method includes making measurements of individual cells.
This method can be used in cancer diagnostic scenarios, Kamm said, and can help researchers look at how cancer cells change in stiffness as they migrate through the body to form tumors in various locations.
When cancer cells metastasize or moves through epithelial tissue, such as the skin, this tool could also tell researchers how the cell is adjusting to do mechanical tasks, Scarcelli said.
“Changes in cell stiffness could be important, according to some research, in determining how invasive or metastatic particular cancer cells are,” Kamm said. “And this lets us look at that information without having to kill the cell.”
Besides looking at cancer cells to see how they move and change their mechanical properties and metastasize, this method can also be used to examine skin cells, which play an important role in wound healing.
“This could work for any types of cells,” Yun said. “We can look at fibroblast cells, which play a role in creating scars and closing a wound, [to see] how they operate.”
In some clinical trials, the technique was also used to measure the stiffness of the cornea to evaluate whether it was safe for people to undergo refractive surgery, Scarcelli said.
“The reason why this is interesting is we can take the cell and we can measure it … in a way you previously couldn’t measure because you couldn’t touch the cell,” Scarcelli said.
Scarcelli said the next step in this development is working to make this technique and technology easily accessible and usable for biological research.
