Conservation max

User:
Garry Walsh, University of Aberdeen School of Medicine, Scotland.

Project:
Examining adhesion of eosinophils under conditions of blood flow in the lungs.

Problem:
Eosinophils are relatively rare and difficult to isolate. "You don't have very many to play with in your experiment," Walsh says. He needed a device that can handle a small number of cells in small volumes.

Solution:
Five years ago, Walsh connected with engineers from Trinity College, Dublin, who asked him to help test a platform with standardized channels and precision fluidic control; the engineers later commercialized the platform through a spin-off company, Cellix. They developed a disposable microfluidic chip containing eight parallel, 400-μm wide microchannels - roughly the dimensions of a postcapillary venule. Walsh coats the channels with adhesion molecules, then flows eosinophils through them. Some researchers create homemade versions of the device from finely pulled capillary tubes and syringe pumps, he says, but he finds that those systems are too labor-intensive and have less run-to-run consistency.

The built in video recorder and analysis software provides both cell count and morphology data. "When we first started doing these sorts of experiments, we would take videos and count them manually," Walsh says.

He is still developing a way to grow endothelial cells (which comprise microcapillary walls) in the channels and working out the best parameters to keep the cells alive.

Cost:
As a beta-tester, Walsh received free use of the platform, including software, but Cellix sells the full commercial system for $100,000. A pack of ten disposable chips costs about $3000.