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.
Experts believe that millions of people who need transplants eventually will benefit from organ printing. "I believe in five years we're going to be able to print simple organs, such as a cardiovascular network or a urethra," Prestwich said.
The five-year study, which is being led by a man who pioneered organ printing, Gabor Forgacs, professor of biological physics at the University of Missouri-Columbia, will begin with unraveling the basic mechanisms by which cells and other parts of a living system work together to form patterns and structures. A central point is understanding what regulates shape changes as a human slowly transforms from a spherical egg to a fully grown person.
Then Forgacs wants to duplicate that shape-change process and apply it to organ printing.
The cells and liquid hydrogel are put in the printer cartridge and then dropped into three-dimensional, 1-microliter dots that form layers as the hydrogel hardens. The cells form tissue that can be implanted into a damaged organ.
Forgacs said he uses Prestwich's hydrogel because of its biocompatibility with other cells. Instead of disappearing, it becomes part of a matrix that is integral to the tissue.
The grant includes an educational component that means at some future date, when the research is further along, an exhibit will explain the work and show it in Salt Lake City at Leonardo in Library Square.