Microfluidics and Single Cells

A microfluidic device that sucks up the contents of one cell at a time—without disturbing its neighbors—is providing researchers with a new way to measure the biochemical properties of single cells (1). The device offers a way to study the diversity between different stem cells, for example, or to probe why some cancer cells from the same tumor respond differently to treatment.

A schematic of the microfluidic device used for single-cell biochemical assays (1).

“From recent studies on various cell types, it’s obviously clear that average cell behavior doesn’t reflect true biological processes,” said Jongyoon Han of the Massachusetts Institute of Technology, a senior author of the new paper. Instead, he said, cells with outlying behaviors not captured by such an average can shift the properties of a whole culture.

“The key challenge for us was the ability to collect a single cell—maybe one migrating particularly fast or showing unique phenotypic characteristics,” Han said. “We want to be able to study those particular, outlying cells without disrupting their environment.” This is particularly important since environment often influences phenotype.

To accomplish this goal, Han and his colleagues designed a microfluidic device that uses hydrodynamic confinement—moving a small fluid volume rapidly to keep its components separate within a larger volume—to collect the contents of single cells. The device has an orifice measuring only five microns—smaller than the width of a cell—and contains chemicals that lyse the cell. Following lysis, the contents of a single cell at the end of the orifice are taken into the device due to the pressure between the cell culture dish and the device. Inside the microfluidic device, the cell contents can be mixed with chemicals of choice and run through a chamber to measure fluorescence.

To test the utility and accuracy of the device, Han’s team measured kinase and GAPDH activity formation in single cells. “For now,” Han said, “we can carry out any assay that can be implemented as a fluorescence detection assay.”

Han and his colleagues are working to automate the system so other researchers can easily adapt it to their own applications. “Cellular heterogeneity is really a big problem right now,” he said. “More and more we need to be able to analyze these individual cells, and this is a new way to do that.”

Reference

1. Sarkar, A., Kolitz, S., Lauffenburger, D.A., Han, J. (2014) Microfluidic probe for single-cell analysis in adherent tissue culture. Nature Communications doi: 10.1038/ncomms4421

via：Biotechniques