New tissue engineering tool creates large patches of precision-designed tissue

Could be used as grafts for burn victims or as cell cultures for the development of therapeutic drugs
August 1, 2012

The placement of the cells is so precise that scientists can spell words (credit: Lian Leng)

University of Toronto researchers have invented a new tissue engineering tool that makes uniform, layered, large patches of engineered tissue that could one day be used as grafts for burn victims or vascular patches.

Along with graduate students from their labs — Lian Leng, Boyang Zhang, and Arianna McAllister —  Associate Professor Axel Guenther of the Department of Mechanical and Industrial Engineering, cross-appointed to the Institute of Biomaterials and Biomedical Engineering (IBBME), and Associate Professor Milica Radisic, core professor at IBBME and the Department of Chemical Engineering and Applied Chemistry, have invented a new device that may allow for the uniform, large-scale engineering of tissue.

“There’s a lot of interest in soft materials, particularly biomaterials,” explains Associate Professor Axel Guenther of the Department of Mechanical and Industrial Engineering, “but until now no one has demonstrated a simple and scalable one-step process to go from microns to centimeters.”

The one-step, continuous formation of mosaic hydrogel sheets (credit: L. Leng et al./Advanced Materials)

Scientists manipulate biomaterials into the micro-device through several channels. The biomaterials are then mixed, causing a chemical reaction that forms a “mosaic hydrogel” — a sheet-like substance compatible with the growth of cells into living tissues, into which different types of cells can be seeded in very precise and controlled placements.

Unique to this new approach to tissue engineering, however, and unlike more typical methods for tissue engineering (for instance, scaffolding, the seeding of cells onto an artificial structure capable of supporting three-dimensional tissue formation), cells planted onto the mosaic hydrogel sheets are precisely incorporated into the mosaic hydrogel sheet just at the time it’s being created — generating the perfect conditions for cells to grow.

The placement of the cells is so precise, in fact, that scientists can spell words, and can precisely mimic the natural placement of cells in living tissues. And by collecting these sheets around a drum, the machine is able to collect layers of cells in thicknesses made to measure: in essence, three dimensional, functional tissues.

“The cells are able to stretch and connect with each other, which is very important for ultimately obtaining functional tissues,” Guenther states.

“My laboratory is currently pursuing different applications of the technology — different tissues,” says Guenther. The device may provide the means to create three-dimensional cell cultures for the development of therapeutic drugs, for instance.”