Culturing particular types of cells in isolation is a basic technique for measuring how they respond to various stimuli, testing new drugs, and similar cell biology tasks. Neuronal cells, which make up the central nervous system in mammals, are both particularly important and particularly hard to culture. They are highly specialized and choosy about their environment--normally they only survive and develop when cultured on a layer of non-neuronal "glial" cells that provide cellular support services. There are usually far more glial cells than neuronal cells, which makes it hard to image neuronal cells and measure their activity against the glial background.
In a paper in the American Chemical Society's journal Langmuir*, NIST researchers detail a microfluidics technique to culture neuronal cells in relative isolation on a variety of cell-culture surfaces, and to pattern the cells on the surface to study the effects of geometry on cell development. The trick is to mask the substrate with multiple alternating layers of positively and negatively charged polymers, building up a so-called polyelectrolyte multilayer (PEM). Properly selected, the PEM coating convinces the neuronal cells that they're in a good environment to attach, develop and produce the characteristic neuron projections and synapses, all without a glial layer.
Even better, according to the NIST team, microfluidic channels can be used to lay down the PEM coating in patterned lines just a few micrometers wide. Neuronal cells will largely confine themselves to the pattern, enabling a variety of cell-geometry experiments, such as measuring the maximum gap between lines that can be bridged by neural axons and dendrites.
The research is part of a multidisciplinary NIST program to develop bioche mical measurement technologies based on microfluidics.