An artist’s depiction of a cell being squeezed in a high speed fluid flow - UCLA
Malignant cells are different from regular cells in their biochemistry as well as in their morphology. Studying physical properties of such cells can often be more advantageous than looking at their biochemical characteristics because labeling is not required and sample preparation is easier to perform.
Scanning through thousands of cells to spot a cancerous one requires a fast device, and researchers at UCLA have developed one called deformability cytometer that can effectively “feel” around the entire perimeter of individual cells, using a liquid flow trap, at 2,000 cells per second.
Some details about the workings of the system:
It consists of a miniaturized microfluidic chip that sequentially aligns cells so that they hit a wall of fluid at rates of thousands of cells per second. A specialized camera captures microscopic images of these cells at intervals of 140,000 pictures per second, and these images are then automatically analyzed by custom software to extract information about the cells’ physical properties.
Mechanical properties can be gleaned by watching a water balloon hit a wall (top) and a cell hit a wall of fluid (bottom) - UCLA
Other researchers had previously discovered that the physical properties of cells could provide useful information about cell health, but previous techniques had been confined to academic research labs because measuring the cells of interest could take hours or even days. Using the deformability cytometer, the group can prepare the samples and conduct the analysis for tens of thousands of cells with the instrument within ten to 30 minutes.
“Our system makes use of an approach that (U.S. Secretary of Energy) Steven Chu used to stretch DNA to, instead, stretch cells,” [assistant professor of bioengineering Dino] Di Carlo said. “This required us to engineer the fluid dynamics of the system such that cells always entered the stretching flow in the same place, making use of inertial focusing technology my group has been pioneering.”
With a system in place to measure the physical properties of cells at much higher rates, the bioengineers teamed up with collaborators across the UCLA campus to measure various cell populations of interest to biologists and doctors.
Along with UCLA stem cell biologist Amander Clark, an assistant professor of of molecular, cellular and developmental biology, Di Carlo’s team confirmed that stem cells that have the capability to become any tissue type stretched much less than their progeny, which were already in the process of becoming a particular tissue.
Link: When cells hit the wall: UCLA engineers put the squeeze on cells to diagnose disease…
Abstract in PNAS: Hydrodynamic stretching of single cells for large population mechanical phenotyping
