Microfluidic chips are going to speed up the rate of biological experimentation by orders of magnitude. Here is another example of the power of microfluidics for studying biological systems.
CHAMPAIGN, Ill. — Researchers at the University of Illinois have developed a method for culturing mammalian neurons in chambers not much larger than the neurons themselves. The new approach extends the lifespan of the neurons at very low densities, an essential step toward developing a method for studying the growth and behavior of individual brain cells.
The technique is described this month in the journal of the Royal Society of Chemistry – Lab on a Chip.
“This finding will be very positively greeted by the neuroscience community,” said Martha Gillette, who is an author on the study and the head of the cell and developmental biology department at Illinois. “This is pushing the limits of what you can do with neurons in culture.”
The small scale allows much greater sensitivity of measurement.
First, the researchers scaled down the size of the fluid-filled chambers used to hold the cells. Chemistry graduate student Matthew Stewart made the small chambers out of a molded gel of polydimethylsiloxane (PDMS). The reduced chamber size also reduced – by several orders of magnitude – the amount of fluid around the cells, said Biotechnology Center director Jonathan Sweedler, an author on the study. This “miniaturization of experimental architectures” will make it easier to identify and measure the substances released by the cells, because these “releasates” are less dilute.
“If you bring the walls in and you make an environment that’s cell-sized, the channels now are such that you’re constraining the releasates to physiological concentrations, even at the level of a single cell,” Sweedler said.
The method used to create the microfluidic chambers
Second, the researchers increased the purity of the material used to form the chambers. Cell and developmental biology graduate student Larry Millet exposed the PDMS to a series of chemical baths to extract impurities that were killing the cells.
This technique allows measurement of cellular secretions.
Millet also developed a method for gradually perfusing the neurons with serum-free media, a technique that resupplies depleted nutrients and removes cellular waste products. The perfusion technique also allows the researchers to collect and analyze other cellular secretions – a key to identifying the biochemical contributions of individual cells.
This technique allows neurons to live longer in culture. Hence more experimental data can be collected and more kinds of processes studied.
This combination of techniques enabled the research team to grow postnatal primary hippocampal neurons from rats for up to 11 days at extremely low densities. Prior to this work, cultured neurons in closed-channel devices made of untreated, native PDMS remained viable for two days at best.
The development of microfluidic devices will bring changes in biotechnology as revolutionary as the changes which miniaturization have caused in the electronics industry. Microfluidics will enable massive parallelism and automation of experiments at very low cost.
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