New method for magnetic manipulation of cells

April 6, 2009
These images reveal cells chained in BSA-ferrofluid. Images (a) through (d) are of cells under a magnetic field forming oriented linear chains. The arrow indicates the direction of the magnetic field. Image (e) is a low magnification view of cells under magnetic field. Image (f) is a view of cell chains one hour after the magnetic field has been removed.

( -- Magnetic technology could help address a major problem that bioengineers face 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 their growth.

A team of investigators from Case Western Reserve University, Duke University and University of Massachusetts, Amherst, created an environment where suspended within a special liquid solution acted like molecular sheep dogs, nudging free-floating to form chains in response to external magnetic fields. These chains, the researchers said, could potentially be integrated into approaches for creating human tissues and organs.

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

“The cells have receptors on their surfaces that have an affinity for other cells,” said Melissa Krebs, a third-year biomedical engineering graduate student at Case Western Reserve University. “They become sticky and attach to each other. When get together in a linear fashion, as they did in our experiments, it may help them to organize into tiny tubules.”

The iron-containing used by the researchers are suspended within a liquid known as a ferrofluid. One of the unique properties of these ferrofluids is that they become highly magnetized in the presence of external magnetism, which allows researchers to readily manipulate the chain formation by altering the strength of the magnetic field.

At the end of the process, the nanoparticles are simply washed away, leaving a linear chain of cells. That the cells remain alive, healthy, and relatively unaltered without any harmful effects from the process is one of the major advances of the new approach over other strategies using magnetism.

“Others have tried using magnetic particles either within or on the surface of the cells,” explained Randall Erb, a 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 and Krebs’ brother. “However, the iron in the nanoparticles can be toxic to cells. Also, the process of removing the nanoparticles afterward can be harmful to the cells and their function.”

The key ingredient for these studies was the synthesis of non-toxic ferrofluids. Researchers developed a method for coating the magnetic nanoparticles with bovine serum albumin (BSA), a protein derived from cow blood. BSA is a stable protein used in many experiments because it is biochemically inert. In these experiments, the BSA shielded the cells from the toxic iron.

“The other main benefit of our approach is that we are creating three-dimensional cell chains without any sophisticated techniques or equipment,” Krebs said. “Any type of tissue we’d ultimately want to engineer will have to be three-dimensional.”

For their experiments, the researchers used human umbilical vein endothelial cells. Others types of cells have also been used, and it appears to the researchers that this new approach can work with any type of cell.

“While still in the early stages, we have shown that we can form oriented cellular structures,” said Eben Alsberg, assistant professor of Biomedical Engineering and Orthopaedic Surgery at Case Western Reserve. “The next step is to see if the spatial arrangement of these cells in three dimensions will promote vascular formation. A major current hurdle in tissue engineering is vascularization, and we hope that this technology may help to address the problem.”

The research, appearing online in advance of the May publication of Nanoletters, a journal published by the American Chemical Society, was supported by the National Institutes of Health, the National Science Foundation and Case Western Reserve University.

Provided by Case Western Reserve University (news : web)

Explore further: Magnetic nano-'shepherds' organize cells

Related Stories

Magnetic nano-'shepherds' organize cells

March 31, 2009

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.

Sophisticated nano-structures assembled with magnets (Video)

February 18, 2009

( -- What do Saturn and flowers have in common? As shapes, both possess certain symmetries that are easily recognizable in the natural world. Now, at an extremely small level, researchers from Duke University ...

Researchers use magnetism to target cells to animal arteries

January 7, 2008

Scientists have used magnetic fields and tiny iron-bearing particles to drive healthy cells to targeted sites in blood vessels. The research, done in animals, may lead to a new method of delivering cells and genes to repair ...

Magnetism shepherds microlenses to excavate 'nanocavities'

March 30, 2006

A Duke University engineer is "herding" tiny lenses with magnetic ferrofluids, precisely aligning them so that they focus bursts of light to excavate patterns of cavities on surfaces. Such photolithographically produced "nanocavities" ...

Magnetic nanoparticles assembled into long chains

October 20, 2005

Chains of 1 million magnetic nanoparticles have been assembled and disassembled in a solution of suspended particles in a controlled way, scientists at the National Institute of Standards and Technology (NIST) report. Such ...

Recommended for you

Chemical treatment improves quantum dot lasers

October 16, 2017

One of the secrets to making tiny laser devices such as opthalmic surgery scalpels work even more efficiently is the use of tiny semiconductor particles, called quantum dots. In new research at Los Alamos National Laboratory's ...

Low-cost battery from waste graphite

October 11, 2017

Lithium ion batteries are flammable and the price of the raw material is rising. Are there alternatives? Yes: Empa and ETH Zürich researchers have discovered promising approaches as to how we might produce batteries out ...


Adjust slider to filter visible comments by rank

Display comments: newest first

1 / 5 (1) Apr 08, 2009
Very interesting. Me thinks we move into a new age of human definition. Once again using our livestock. Will it change us again? Propabably. But's that's how we mammals like it, adapt or bye, bye.
1 / 5 (1) Apr 09, 2009
Isnt blood a ferrofluid? How does the iron concentration compare with this ferrofluid-BSA mixture?
3 / 5 (2) Apr 17, 2009
No, blood is not a ferrofluid, seeing as how it does not "become highly magnetized in the presence of external magnetism"

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.