U. makes a healing 'bio-paper'

An emerging branch of medicine called "organ printing" takes a patient's own healthy cells and uses a printer, cell-based "bio-ink" and "bio-paper" to create tissue to repair a damaged organ.

Now a hydrogel or "bio-paper" developed by a University of Utah College of Pharmacy professor is a key component of a $5 million National Science Foundation-sponsored study that includes organ printing.

"Think of taking a blood vessel — a cylindrical object — and trying to reconstruct it in 3D with two-dimensional slices," said U. Presidential Professor of Medicinal Chemistry Glenn D. Prestwich, who created the hydrogel. He likens the resulting slices to a "non-nutritious doughnut" with muscle cells on the outside and endothelial cells inside. To make the cylinder, those flat doughnut sections are literally printed, one thin layer of cells and hydrogel at a time, the platform moving away from the printer's "bio-ink"-delivering needles as the cylinder grows.

The cells in the gel are alive and will begin to move from one side to the other, one "doughnut" to the other, fusing and interweaving to form a complete, living cylinder. The advantage of his hydrogel over others, Prestwich said, is the cells will stick to them well. They don't with others, which are typically made of synthetic polymers.

His hydrogel is made of normal biological material from the body, two sugar chains that, mixed with a reactive substance, turn from liquid into gel. It's the type of biologic filler that is used in ophthalmic surgery, in injections in knee joints to ease pain or in the face to erase tiny wrinkles.

"We've put a chemical handle on it, sort of like Velcro, to make something cells like and will attach to. The cells eat it up, then secrete a new tissue matrix that's needed for the tissue to function. And those become part of the final product."

Prestwich began working on creating the hydrogel when he arrived at the U. in 1996 and he had developed a functioning material for wound-healing applications by 2000. Now researchers are hoping to use it to repair damaged organs in real time.

The NSF study will try first to print blood vessels and cardiovascular networks. Once they prove it can be done, the scientists will look at more complex organs such as livers and kidneys and simpler but more mechanical organs like the esophagus, Prestwich said.

The hydrogel has other uses. Besides use in organ printing, Prestwich believes it is about ready for prime time in basic medicine applications. He said he expects it will be used in humans within the next year, perhaps in treatment of chronic sinusitis.