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Campus Currents May 2007: Volume 4, Number 2

Tissue Engineering

Nanoengineers at UC San Diego have invented a new biomaterial that more closely mimics human tissue. The breakthrough could make future tissue patches, which are used to repair damaged heart walls after a heart attack, more compatible and effective, according to Professor Shaochen Chen.

Tissue patches are loaded with new cells that mingle with existing tissue and regenerate damaged sections. When the heart stretches and contracts as part of normal blood flow, natural heart tissue exhibits the very unique property of expanding. The newly invented biomaterial has overcome a significant limitation of today's tissue patches: a tendency to shrink or wrinkle in the middle when stretched.

This breakthrough in tissue engineering is maintained whether the tissue patch has one or multiple layers. One layer is double the thickness of a human hair, and the number of layers used in a tissue patch depends on the thickness of the tissue that doctors are trying to repair. A single layer would not be thick enough to repair a heart wall or skin tissue. Chen's findings were published in a recent issue of the journal Advanced Functional Materials.

The biomaterial was created using a new biofabrication platform that Chen is developing under a four-year, $1.5 million grant from the National Institutes of Health. This biofabrication technique uses a computer projection system and precisely controlled micromirrors to shine light on a selected area of a solution containing photo-sensitive biopolymers and cells. This photo-induced solidification process forms one layer of solid structure at a time. The process enables nanoengineers to build three-dimensional, designer scaffolds with patterns of any shape. Chen's team created two shapes called "reentrant honeycomb" and "cut missing rib" that exhibit the unique quality of expanding (rather than shrinking) when stretched, and maintain this quality whether the tissue patch has one or multiple layers.

The next phase of research will involve working with the department of bioengineering to make tissue grafts to repair damaged blood vessels.

Chen joined the UCSD faculty in 2010 after spending two years as program director for the nanomanufacturing program at the National Science Foundation and as faculty at the University of Texas at Austin.

—Catherine Hockmuth