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Sandia Technology logo A quarterly research and development magazine

Summer 2007
Volume 9, No. 2

SANDIA TECHNOLOGY MAGAZINE

Looking at immune response one cell at a time, cont.

cell-preparation module
Cell-preparation module that is part of a MISL chip

MISL chip
Top of MISL chip with cell imaging area at right
“We’re starting with robust and well-characterized cells, which simplifies development of our new technologies and methods,” Singh says. “We’ll soon be working with other cell types, though, like white blood cells isolated from human patients. Our approach is designed to be flexible enough to handle many different cell types, and it also minimizes the number of cells needed for analysis, so it should enable us to do some unique studies on rare cell types.”

Proteins in the cells of interest are tagged with fluorescent molecules, essentially colored dyes. The dyes give researchers the opportunity to track proteins and see, for example, the dynamic cellular production of proteins or protein-binding processes inside or on the surfaces of the cells.

The team is developing one platform with two complementary microfluidic modules. One traps and images viable cells during stimulation with pathogens. The other combines cell preparation steps, cell selection, and sorting and analyzes protein content in the selected cell subpopulations.

“In effect, we are taking many workhorse technologies such as confocal microscopy, flow cytometry, and immunoassays and combining them into one compact, miniaturized platform using our unique microfluidic and imaging tools,” Singh says.

macrophage cell
Macrophage cell carrying green fluorescent- labeled protein

infected macrophage cell
Macrophage cell infected with Francisella tularensis novicid, a form of the bacteria that causes tularemia, or rabbit fever
Hyperspectral fluorescence imaging with multivariate curve resolution is used to image the tagged proteins and provide quantitative measurements on multiple proteins simultaneously. The goal is to analyze as many as 10 to 40 proteins and cellular stains at a time in three dimensions.

The end result of the imaging and protein analysis is a large amount of data that must be categorized and understood. Computational modeling is then used to develop network models from experimental data, and predictive modeling generates hypotheses to be tested next.

Singh says Sandia researchers have been working in microfluidics — the science of designing, manufacturing, and formulating devices and processes that deal with volumes of fluid on the order of nanoliters — since the 1990s and have a good understanding about how to use microfluidics to analyze cell activity. The microfluidic platform is fast and highly parallel and can perform measurements 50 to 100 times faster than alternate methods.

Singh says the goal of the work is to make a benchtop miniaturized system, expected in about two years. It would be placed in highly secure labs to study immune response to pathogenic organisms.

The integrated platform, biological reagents, and computational models developed under this project have applicability beyond infectious disease research, says Singh. These technologies can also be used for studying cellular signaling involved in diseases such as cancer. Pharmaceutical companies might make use of it for biomarker discovery, he says.

For more information: http://roswell.ca.sandia.gov/anup.

Technical contact: Anup Singh, (925) 294-1260, aksingh@sandia.gov
Media contact: Chris Burroughs, (505) 844-0948, coburro@sandia.gov