Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Tracking Stem Cells Implanted Into A Living Animal

18.12.2001


Using tiny rust-containing spheres to tag cells, scientists from Johns Hopkins and elsewhere have successfully used magnetic resonance imaging to track stem cells implanted into a living animal, believed to be a first.



In the December issue of the journal Nature Biotechnology, the research team report that the neuronal stem cells take up and hold onto the spheres, which contain a compound of iron and oxygen. The iron-laden cells create a magnetic black hole easily spotted by magnetic resonance imaging (MRI), they report.

"Until now, tissue had to be removed from an animal to see where stem cells were going, so this gives us an important tool," says author Jeff Bulte, Ph.D., associate professor of radiology at the Johns Hopkins School of Medicine. "Tracking stem cells non-invasively will likely be required as research advances, although human studies are still some time away."


Scientists at the University of Wisconsin School of Veterinary Medicine mixed the magnetic spheres, made by Trevor Douglas at Temple University, with stem cells that make the white matter, or neuronal covering, of the brain. Then they injected the iron-laden cells into the brains of rats that lack that covering.

Using MRI scanners at the National Institutes of Health, Bulte watched the cells travel away from the injection site. The research was funded by the National Science Foundation, the Oscar Rennebohm Foundation and the Keck Foundation.

The rusty spheres, known as magnetic dendrimers, represent an important improvement over other magnetic tags, Bulte says. And even though the amount of iron used to label the cells is tiny compared to the total amount of iron in the body, the labeled cells stand out from other cells, magnetically speaking.

"During scanning, these labeled cells disturb the magnetic field created by the MRI machine, causing water molecules that pass by to get ’out of phase,’" Bulte explains. "When this happens, the imaging scanner loses the signal, and the area looks black on the image."

Other researchers have used dendrimers containing gadolinium, which is also useful as a contrast medium for MRI, but which is toxic if it stays in the body for a prolonged time. But animal cells have a process to deal with iron and a storage mechanism for the metal, making the iron-based dendrimers inherently safer, says Bulte. For instance, iron is a key part of the transporter for oxygen and carbon monoxide found in red blood cells.

He adds that while it was not easy to develop the way to make magnetic dendrimers, it is easy to label cells with them. In essence, the dendrimer and the cell do that work themselves. Dendrimers stick to cells because they are charged -- similar to static electricity. Cells then suck them inside and lock them away in the cellular equivalent of a garbage can -- a tiny holding spot called an endosome.

Other magnetic tags have used antibodies or other molecules that recognize and bind to certain features on cells, says Bulte. Unlike those tags, the magnetic dendrimers are universal; the scientists showed that different cell types will take in dendrimers just by mixing the spheres and the cells together, without affecting the cells’ behavior.

Bulte’s research with magnetic dendrimers is aligned with the Johns Hopkins Institute of Cell Engineering, created in early 2001 to advance research into the biology and potential application of pluripotent stem cells (primitive cells that become any type of cell in the body) and multipotent or adult stem cells (precursor cells that are naturally limited to becoming a specific tissue’s cell types).

A next step with magnetic dendrimers, Bulte says, is watching the cells’ distribution when they are injected into the circulatory system instead of the brain.

Bulte also wants to study white blood cells in diseases of the central nervous system, such as multiple sclerosis, as well as the behavior of embryonic stem cells and stem cells from bone marrow. (Stem cells from bone marrow and blood have been used for decades in cancer treatments and more recently for some inherited metabolic disorders.)

Other co-authors of the report are Ian Duncan, Brian Witwer and Su-Chun Zhang of the University of Wisconsin School of Veterinary Medicine; Erica Strable of Temple University; Joseph Frank, Bobbi Lewis, Holly Zywicke, Brad Miller and Peter van Gelderen of the NIH; and Bruce Moskowitz of the Institute for Rock Magnetism at the University of Minnesota, Minneapolis. Bulte (NIH) and Douglas (Temple) have applied for a patent on these magnetic dendrimers.

Joanna Downer | International Science News

More articles from Life Sciences:

nachricht World’s Largest Study on Allergic Rhinitis Reveals new Risk Genes
17.07.2018 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt

nachricht Plant mothers talk to their embryos via the hormone auxin
17.07.2018 | Institute of Science and Technology Austria

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Microscopic trampoline may help create networks of quantum computers

17.07.2018 | Information Technology

In borophene, boundaries are no barrier

17.07.2018 | Materials Sciences

The role of Sodium for the Enhancement of Solar Cells

17.07.2018 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>