Magnetic nano-'shepherds' organize cells( DURHAM N.C. -- The power of magnetis...)

DURHAM, N.C. -- The power of magnetism may address a major problem facing bioengineers as they try to create new tissue -- getting human cells to not only form structures, but to stimulate the growth of blood vessels to nourish that growth.

A multidisciplinary team of investigators from Duke University, Case Western Reserve University and the University of Massachusetts, Amherst created an environment where magnetic particles suspended within a specialized solution act like molecular sheep dogs. In response to external magnetic fields, the shepherds nudge free-floating human cells to form chains which could potentially be integrated into approaches for creating human tissues and organs.

The cells not only naturally adhere to each other upon contact, the researchers said, but the aligned cellular configurations may promote or accelerate the creation and growth of tiny blood vessels.

"We have developed an exciting way of using magnetism to manipulate human cells floating freely in a solution containing magnetic nanoparticles" said Randall Erb, fourth-year graduate student in the laboratory of Benjamin Yellen, assistant professor of Mechanical Engineering and Materials Science, at Duke University's Pratt School of Engineering. "This new cell assembly process holds much promise for tissue engineering research and offers a novel way to organize cells in an inexpensive, easily accessible way."

Melissa Krebs, third-year biomedical engineering graduate student at Case Western and Erb's sister, co-authored a paper appearing online in advance of the May publication of Nano Letters, a journal published by the American Chemical Society.

"The cells have receptors on their surfaces that have an affinity for other cells," Krebs said. "They become sticky and attach to each other. When endothelial cells get together in a linear fashion, as they did in our experiments, it may help them to organize into tiny tubules."

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