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Spotlighted Research

In a paper published in Nature Methods, HSCI Imaging Program Leader Ralph Weissleder and a team of scientists at Massachusetts General Hospital describe a new method for visualizing living cells both in tissue culture and in animal models.

This method provides a new way for scientists to monitor cells, cell processes, and molecular targets. The team's work will play a critical role in advancing the field of stem cell research because scientists will be able to use the technique to help uncover the molecular and cellular details of stem cell development and differentiation.

"This is a powerful technique that can be broadly applied," said David Scadden, co-Scientific Director of HSCI. "It will allow researchers to track stem cell after they have been transferred into an animal model."

In this technique, a reporter gene is transferred to the cells in question. A reporter gene is a piece of DNA that encodes a special reporter protein, which can then be tracked by a conjugate molecule. In this case, the reporter gene codes for a protein that first binds to biotin (vitamin H) and then moves to the surface of the cell.

Once this biotin-protein complex is present on the cell's surface, it can bind to the imaging agent. An imaging agent is a two-part molecule designed by the researcher for the purpose of visualization. When cells that have the biotin-protein complex on their surface are in the presence of the imaging agent, it binds to the biotin-protein complex and allows the cells to be seen.

This technique is versatile for two reasons. The first is that any type of cell can be made to express biotin on its surface by using the reporter gene. The second is that the imaging agent can be constructed using different types of signaling molecules. This provides researchers with multiple options for visualizing their cells - whether it be with fluorochromes, magnetic resonance, PET or SPECT agents.

Versatility is particularly important in stem cell research because the field involves so many different tissue and cell types. This paper provides researchers with a new method for tracking cells in a wide range of environments and models.

Tannous BA, Grimm J, Perry KF, Chen JW, Weissleder R, Breakefield XO. Metabolic biotinylation of cell surface receptors for in vivo imaging. Nat Methods. 2006 May;3(5):391-6. Read Abstract.

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The Harvard Stem Cell Institute is a scientific collaborative established to fulfill the promise of stem cell biology as the basis for cures and treatments for a wide range of chronic medical conditions.

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Photo courtesy of B.D.Colen.
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