With the rapid approach of the Winter Games, Olympic rings seem to be everywhere. But only one is less than an eighth-inch wide, formed from living nerve cells, made with the same technology that may one day repair damaged spinal cords.
University of Utah bioengineering graduate student Mike Manwaring of Pleasant Grove created the "living rings" in response to a challenge from bioengineering assistant professor Patrick Tresco.
The itty-bitty icon glows bright red in a photograph given to Gov. Mike Leavitt during a recent visit to the lab, where the nerve cells were grown on a scaffolding similar to what might one day fix spinal cord injuries or brain damage. In the photo, they look large, but each ring is just four times the width of a human hair. Each nerve fiber in the rings is one-fiftieth of that human hair.
"We came up with this in October, in the aftermath of Sept. 11," said Tresco. "We wanted to create something uplifting. We know we can do neat engineering feats with neurons. This is a wonderful way to demonstrate what we're doing" with tissue engineering. "It's a recognized symbol and clearly didn't happen by chance."
Tresco's lab explores many ways to control cell behaviors on material, with a goal of one day using the applications in nerve or tissue repair. The materials used cause the cells to shape in a particular way, though the materials used for the rings are not all the same as what would be used in human patients.
Originally, it was intended as an interesting photographic souvenir for the governor. It was simply too cool not to share with others, they decided.
Using tissue engineering to reconnect damaged nerves in spinal cord injuries is years away, but it's another sign that "biological discovery and engineering know-how" may one day be able to "rebuild the human nervous system," Tresco said. And the "rings" are yet another step in learning how to control the direction of nerve growth.
Making the rings (no longer alive, since preservation required that they be destroyed) involved a photolithographic process similar to making circuit boards. A high-quality printer made a tiny pattern in the shape of the Olympic rings. A plastic-like polymer substance was sprayed on a piece of brass and the pattern was put on it, then exposed to ultraviolet light to affix the plastic coating everywhere except where the pattern was. The little mold was then etched with acid and rubbery silicon poured over it.
After that, Manwaring applied polystyrene to the silicon rings, using both heat and pressure to create a new, transparent mold. A protein called fibronectin, normally found in and around tissue cells, was made to stick to the mold, then it was placed in a culture dish with a liquid to promote growth. Meningcal fibroblasts, the cells forming connective tissue around the brain and spinal cord, were added and cultured with the fibronectin-coated mold. That made the fibroblasts grow in the mold, forming "live scaffolding" in the shape of the Olympic Rings.
Finally, the nerve cells, taken from adult rats, were placed in the culture dish for 96 hours. They stuck to the fibroblast cells and grew in the shape of the Olympic rings.
The picture was taken using a microscope camera after adding antibodies with a fluorescent red dye to the culture, which was transparent. The nerve cell bodies glow brightest red and the nerve fibers and fibroblast cells a less intense shade.