Gene Expression Dramatically Affected When Nerve Cells Grown In 3-D

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Gene Expression Dramatically Affected When Nerve Cells Grown In 3-D

http://www.medicalnewstoday.com/medicalnews.php?newsid=71237

When it comes to growing cells in a lab, technique matters. A new

Brown University study shows that nerve cells grown in three-

dimensional cultures use 1,766 genes differently compared to nerve

cells grown in standard two-dimensional petri dishes.

The study, published in the May issue of Tissue Engineering, adds to

a growing body of research showing that culture techniques can

significantly affect cell growth and function. This research shows

that cells grown in a laboratory in 3-D environments, not in flat

petri dishes, are more like cells grown in the ultimate 3-D

environment - the human body.

" More and more, we're seeing evidence that cells cultured in three

dimensions look and behave more like cells in your body, " said Diane

Hoffman-Kim, the Brown bioengineer who spearheaded the new

study, " so culture method is critical. If you want to better

understand how the human body behaves or how new drugs might fight

disease, 3-D may be a better bet. "

For more than 100 years, scientists have grown human cells in flat

dishes. In these 2-D glass incubators, better known as petri dishes,

cells stick to the bottom and spread out as they multiply. But in

the body, cells don't grow that way. They are suspended in fluids

and gels and surrounded by other cells. And these cells aren't

stuck; they move.

As a result, some scientists suspect that hothouse cells do not

behave like in vivo varieties. This means that the critical

functions scientists are trying to understand by studying these

cells - from the proliferation of cancer to the bacterial assault by

antibiotics - may play out differently. Studies indeed show

differences in behavior between cells cultured in 2-D and in 3-D.

Cells cultured in 3-D, for example, grow faster.

Hoffman-Kim, an assistant professor of medical science and

engineering at Brown, wants to find a way to repair damaged nerve

tissue. To get there, she needs to grow nerve cells that will

flourish when placed inside the body. So Hoffman-Kim put 2-D and 3-D

cell culture methods to a comparative test. Would the cells be

different " Which ones would grow best "

To answer that question, Hoffman-Kim and researchers in her lab took

a line of cancerous nerve cells and cultured them in different

environments. They placed one batch of cells in standard petri

dishes coated with collagen. They suspended the other batch in a

thicker collagen gel. The bioengineers took great pains to be sure

that this one-dimension difference was the only difference in the

culture conditions. Team members even counted individuals cells as

they went into the dishes to be sure that each dish contained

precisely the same amount.

After a day of growth, the researchers extracted RNA from the cells

and conducted a microarray analysis to determine differences in gene

activity. The results: A whopping 1,766 genes responded differently,

either switching on or switching off. To check their work,

researchers repeated the experiments but this time produced multiple

copies of eight genes specifically linked to cell growth. Those

experiments confirmed the differences in gene activity.

Hoffman-Kim and her team deployed high-powered microscopes to detect

other differences. Cells cultured in 3-D had a rounder, more

realistic shape, and their neurites - spindly projections sprouting

from the cell body - were longer.

" The cells in 3-D culture grew faster and looked more like the

body's cells, " she said. " This means that this culture method might

create tissue that could be more successfully implanted. "

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Graduate student Grace Li and senior research assistant Liane Livi

were the lead authors of the Tissue Engineering article. Graduate

student Celinda Gourd and graduate alumna Deweerd also

served on the research team. All are members of Brown's Center for

Biomedical Engineering and the Department of Molecular Pharmacology,

Physiology, and Biotechnology in The Warren Alpert Medical School of

Brown University.

The National Center for Research Resources, part of the National

Institutes of Health, funded the work through Brown University's

Center for Genetics and Genomics.