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.”
Growing viable mammalian neurons at low density in an artificial environment is no easy task. Using postnatal neurons only adds to the challenge, Gillette said, because these cells are extremely sensitive to environmental conditions.
All neurons rely on a steady supply of proteins and other “trophic factors” present in the extracellular fluid. These factors are secreted by the neurons themselves or by support cells, such as the glia. This is why neurons tend to do best when grown at high density and in the presence of other brain cells. But a dense or complex mixture of cells complicates the task of characterizing the behavior of individual neurons.
One technique for keeping neural cultures alive is to grow the cells in a medium that contains serum, or blood plasma. This increases the viability of cells grown at low density, but it also “contaminates” the culture, making it difficult to determine which substances were produced by the cells and which came from the serum.
Those hoping to understand the cellular origins of trophic factors in the brain would benefit from a technique that allows them to measure the chemical outputs of individual cells. The research team made progress toward this goal by addressing a few key obstacles.
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.
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.
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.
“We know there are factors that are communicated in the media between the cells,” Millet said. “The question is what are they, and how can we get at those?”
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 cultured neurons also developed more axons and dendrites, the neural tendrils that communicate with other cells, than those grown at low densities with conventional techniques, Gillette said.
“Not only have we increased the cells’ viability, we’ve also increased their ability to differentiate into what looks much more like a mature neuron,” she said.
Sweedler noted that the team’s successes are the result of a unique collaboration among scientists with very different backgrounds.
“(Materials science and engineering professor) Ralph Nuzzo is one of the pioneers in self-assembled monolayers and surface chemistry,” Sweedler said. “Martha Gillette’s expertise is in understanding how these neurons grow, and in imaging them. My lab does measurement science on a very small scale. It’s almost impossible for any one lab to do all that.”
Nuzzo and Sweedler are William H. and Janet Lycan professors of chemistry. Gillette is Alumni Professor of Cell and Developmental Biology. All are appointed in the Institute for Genomic Biology. Sweedler and Gillette are affiliates of the Beckman Institute and the Neuroscience Program. Sweedler is a professor in the Bioengineering Program and Gillette in the College of Medicine.
To view or subscribe to the RSS feed for Science News at Illinois, please go to: http://webtools.uiuc.edu/rssManager/608/rss.xml.Editor’s note: To reach Martha Gillette, call 217-244-1355; e-mail: mailto:email@example.com.
Diana Yates | University of Illinois
Multi-institutional collaboration uncovers how molecular machines assemble
02.12.2016 | Salk Institute
Fertilized egg cells trigger and monitor loss of sperm’s epigenetic memory
02.12.2016 | IMBA - Institut für Molekulare Biotechnologie der Österreichischen Akademie der Wissenschaften GmbH
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water
In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...
The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.
Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
02.12.2016 | Medical Engineering
02.12.2016 | Agricultural and Forestry Science
02.12.2016 | Physics and Astronomy