CU-Boulder Researchers Develop New 3-D Platform for Growing Cells

April 15, 2009

It's easy enough for researchers in a laboratory to grow the cells they rely on for their work. Put them in a petri dish with a hospitable fluid, keep them at the right temperature and take care not to expose them to anything that might stunt their growth and soon the tiny specs will be bouncing baby cells, ready for whatever experiments scientist choose to use them for.

The problem with this tried-and-true method is that very few cells grow that way naturally. A petri dish is a two-dimensional home for a cell that would normally grow in a 3-D environment, like a living organism.

"There's a lot of interest in developing better cell culture platforms," said April Kloxin, a postdoctoral research associate with the Howard Hughes Medical Institute and the department of chemical and biological engineering at CU-Boulder. "There has been a lot of 2-D work, but research has shown that it's important that it happen in 3-D, in a situation that mimics the way it happens in the body."

To solve that problem Kloxin and chemical and biological engineering Distinguished Professor Kristi Anseth have developed a new cell culture platform that allows for more realistic experiments. The team's paper on the new substance was published this month in the journal Science.

"We're really interested in how the culture environment of a cell influences cell function," said Kloxin. "We wanted to develop a culture that gives the researcher control of the cell microenvironment, of what the cell sees and feels in the culture."

To alter the cell environment, the team incorporated light-responsive molecules into the mix. When light is focused on an area of the culture, the properties of the culture material change. Other approaches to changing the material properties include degradation with water or by the cells themselves, but the new approach uses light, allowing the researcher to externally trigger changes in the material properties.

"What we have is a tool that allows us to quickly and easily tune the properties of the cell's environment and see how it affects cell function," said Kloxin. "I think that we have good control over what we've produced. Now it's a matter of people using it for their particular cell application."

The material, a hydrogel, consists of repeating chains of complex molecules known as polymers that swell in water. Produced in sheets one-half millimeter thick or smaller, they have the consistency of firm Jell-O.

Hydrogels, including the one created by Anseth's team made of polyethylene glycol, are useful in studying cell growth because they have the same elasticity and water content as the human body.

"These gels offer an unprecedented level of control of both the chemistry and mechanics of the cell environment," said Anseth.

Kloxin and Anseth are using the environment they've created to study how material properties influence things like cell differentiation, cell morphology and migration.

The researchers want to know if the material will be able to direct neuron processes by taking two cells of interest and enabling them to connect and communicate, said Kloxin.

Anseth said the material's possible uses could be many and varied.

"We hope that these materials will not only provide a better system for culturing cells in three dimensions, but that engineers will be able to use the materials to regenerate complex tissues important for medical applications," she said.

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