[Editors] MIT works toward engineered blood vessels

[Elizabeth Thomson]

MIT News Office
Massachusetts Institute of Technology
Room 11-400
77 Massachusetts Avenue
Cambridge, MA  02139-4307
Phone: 617-253-2700
http://web.mit.edu/newsoffice/www

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MIT works toward engineered blood vessels

--Tissue could be used in human body

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For Immediate Release
MONDAY, DEC. 17, 2007
Contact: Elizabeth A. Thomson, MIT News Office -- Phone: 617-258-5402  
-- Email: thomson at mit.edu

PHOTO, GRAPHIC AVAILABLE


CAMBRIDGE, Mass.-MIT scientists have found a way to induce cells to  
form parallel tube-like structures that could one day serve as tiny  
engineered blood vessels.

The researchers found that they can control the cells' development by  
growing them on a surface with nano-scale patterning. A paper on the  
work was posted this month in an online issue of Advanced Materials.

Engineered blood vessels could one day be transplanted into tissues  
such as the kidneys, liver, heart or any other organs that require  
large amounts of vascular tissue, which moves nutrients, gases and  
waste to and from cells.

"We are very excited about this work,” said Robert Langer, MIT  
Institute Professor and an author of the paper. “It provides a new  
way to create nano-based systems with what we hope will provide a  
novel way to someday engineer tissues in the human body.”

The work focuses on vascular tissue, which includes capillaries, the  
tiniest blood vessels, and is an important part of the circulatory  
system. The team has created a surface that can serve as a template  
to grow capillary tubes aligned in a specific direction.

The researchers built their template using microfabrication machinery  
at Draper Laboratory in Cambridge. Normally such technology is used  
to build micro-scale devices, but the researchers adapted it to  
create nano-scale patterns on a silicone elastomer substrate. The  
surface is patterned with ridges and grooves that guide the cells'  
growth.

“The cells can sense (the patterns), and they end up elongated in the  
direction of those grooves,” said Christopher Bettinger, MIT graduate  
student in materials science and engineering and lead author of the  
paper.

The cells, known as endothelial progenitor cells (EPCs), not only  
elongate in the direction of the grooves, but also align themselves  
along the grooves. That results in a multicellular structure with  
defined edges, also called a band structure.

Once the band structures form, the researchers apply a commonly used  
gel that induces cells to form three-dimensional tubes. Unlike cells  
grown on a flat surface, which form a network of capillary tubes  
extending in random directions, cells grown on the nano-patterned  
surface form capillaries aligned in the direction chosen by the  
researchers.

The researchers believe the technique works best with EPCs because  
they are relatively immature cells. Earlier attempts with other types  
of cells, including mature epithelial cells, did not produce band  
structures.

Growing tissue on a patterned surface allows researchers a much  
greater degree of control over the results than the classic tissue  
engineering technique of mixing cell types with different growth  
factors and hoping that a useful type of tissue is produced, said  
Bettinger.

“With this technique, we can take the guesswork out of it,” he said.

The next step is to implant capillary tubes grown in the lab into  
tissues of living animals and try to integrate them into the tissues.

Other authors of the paper are Jeffrey Borenstein, director of the  
Biomedical Engineering Center at Draper Laboratory; Zhitong Zhang, an  
MIT senior in the Department of Chemical Engineering; and Sharon  
Gerecht of Johns Hopkins University.

The research was funded by the National Institutes of Health, Draper  
Laboratory and the Juvenile Diabetes Research Foundation.

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Written by Anne Trafton, MIT News Office