New microscopy technique to shed new light on aging, healing
The technique developed by researchers from from the University of Maryland (UMD), Massachusetts Institute of Technology (MIT), and Massachusetts General Hospital, offers promise that one day researchers will be able to identify a more exact starting point for the development of cancers, coronary disease, or even osteoporosis.
"Using light, we can measure cells inside tissue and we can look inside the cells to distinguish, for example, the properties of the nucleus and cytoplasm," said team lead Dr. Giuliano Scarcelli, assistant professor with UMD's Fischell Department of Bioengineering.
In order to better understand how such diseases develop – and in efforts to learn more about factors that influence everyday biological functions – researchers need to get a clearer look at how properties of a cell change over time.
Every cell contains a cytoplasm – the thick solution enclosed within the cell by the cell membrane. Primarily composed of water, salts, and proteins, the cytoplasm is where most cellular activities occur.
Even more, the cytoplasm serves as a means of transport for genetic material and acts as a buffer, protecting the cell's genetic material from damage due to movement or collision with other cells.
For years, researchers have known that the interaction between the liquid and solid phases within the cytoplasm plays a prominent role in how cells deform and move.
As such, the ability to map the hydro-mechanical properties of cells – such as viscoelasticity and compressibility – is critical to advancing understanding of how cell properties change as a symptom of disease in the body or as part of normal biological functions, such as when wounds heal.
Traditionally, techniques used to study the mechanical properties of cells have either required contact with cells or have produced images with limited resolution. As a result, information on the biomechanical properties of cells in 3-D environments is lacking.
"Gold-standard techniques require contact, therefore they are inherently limited to providing global averages of cell properties and to experimental situations where you have physical access to the cell," Scarcelli said.
To address this, Scarcelli and six researchers have introduced a technique known as Brillouin optical cell microscopy for noninvasive, 3-D mapping of intracellular and extracellular hydro-mechanical properties.
Their technique – published this week in Nature Methods – employs Brillouin light scattering, a process that occurs when light interacts with density fluctuations in a medium.
These spontaneous fluctuations are driven by collective acoustic vibrational modes, known as phonons, in the gigahertz frequency range. In this way, Brillouin microscopy yields invaluable information on the viscoelastic characteristics of cells – and does so at a microscopic resolution no other technique can match.
As such, Brillouin microscopy opens up new research avenues for the biomechanical investigation of cells and their microenvironment in 3-D at subcellular resolution. ■