[Editors] MIT creates tiny backpacks for cells-could ferry drugs, assist in cancer diagnosis

[Teresa Herbert]

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MIT creates tiny backpacks for cells
-Polymer patches could ferry drugs, assist in cancer diagnosis
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For Immediate Release
WEDNESDAY, NOV. 5, 2008

Contact: Teresa Herbert, MIT News Office
E: therbert at mit.edu, T: 617-258-5403

Photo and Video Available


CAMBRIDGE, Mass. -- MIT engineers have outfitted cells with tiny  
“backpacks” that could allow them to deliver chemotherapy agents,  
diagnose tumors or become building blocks for tissue engineering.

Michael Rubner, director of MIT’s Center for Materials Science and  
Engineering and senior author of a paper on the work that appeared  
online in Nano Letters on Nov. 5, said he believes this is the first  
time anyone has attached such a synthetic patch to a cell.

The polymer backpacks allow researchers to use cells to ferry tiny  
cargoes and manipulate their movements using magnetic fields. Since  
each patch covers only a small portion of the cell surface, it does  
not interfere with the cell’s normal functions or prevent it from  
interacting with the external environment.

“The goal is to perturb the cell as little as possible,” said Robert  
Cohen, the St. Laurent Professor of Chemical Engineering at MIT and an  
author of the paper.

The researchers worked with B and T cells, two types of immune cells  
that can home to various tissues in the body, including tumors,  
infection sites, and lymphoid tissues — a trait that could be  
exploited to achieve targeted drug or vaccine delivery.

“The idea is that we use cells as vectors to carry materials to  
tumors, infection sites or other tissue sites,” said Darrell Irvine,  
an author of the paper and associate professor of materials science  
and engineering and biological engineering.

Cellular backpacks carrying chemotherapy agents could target tumor  
cells, while cells equipped with patches carrying imaging agents could  
help identify tumors by binding to protein markers expressed by cancer  
cells.

Another possible application is in tissue engineering. Patches could  
be designed that allow researchers to align cells in a certain  
pattern, eliminating the need for a tissue scaffold.

The polymer patch system consists of three layers, each with a  
different function, stacked onto a surface. The bottom layer tethers  
the polymer to the surface, the middle layer contains the payload, and  
the top layer serves as a “hook” that catches and binds cells.

Once the layers are set up, cells enter the system and flow across the  
surface, getting stuck on the polymer hooks. The patch is then  
detached from the surface by simply lowering the temperature, and the  
cells float away, with backpacks attached.

“The rest of the cell is untouched and able to interact with the  
environment,” said Albert Swiston, lead author of the paper and a  
graduate student in materials science and engineering.

The researchers found that T cells with backpacks were able to perform  
their normal functions, including migrating across a surface, just as  
they would without anything attached.

By loading the backpacks with magnetic nanoparticles, the researchers  
can control the cells’ movement with a magnetic field.

Because the polymer synthesis and assembly takes place before the  
patches are attached to cells, there is plenty of opportunity to tweak  
the process to improve the polymers’ effectiveness and ensure they  
won’t be toxic to cells, the researchers say.

Other authors of the paper are Soong Ho Um, a postdoctoral associate  
in the Departments of Materials Science and Engineering and Biological  
Engineering, and Connie Cheng, a recent Harvard graduate.

The research was funded by the National Science Foundation Materials  
Research Science and Engineering Center and an NSF Graduate Research  
Fellowship.

By Anne Trafton, MIT News Office

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