An ISU professor’s experiments with nerve regeneration may hold the key to helping the paralyzed walk.

Using an ultra-thin biodegradable polymer placed in the peripheral nervous cell, Surya Mallapragada, associate professor in chemical engineering, has been able to generate the regrowth of nerve cells. Mallapragada’s polymer cut micro-scale grooves to guide nerve cells that have been severed in the peripheral nervous system. These grooves guide the cells to grow in the right direction.

The polymer is biodegradable so the polymer can be planted but does not have to be surgically removed. The polymer biodegrades with the presence of water, she said.

“We can vary the composition of the polymer to biodegrade at different times,” Mallapragada said. “It may take a few days or a few months.”

Grafting, the process of planting cells from another area, works well for repairing skin tissue. This doesn’t work well in nerve cell regrowth, because the cells needed guidance to reconnect, Mallapragada said. A myelin sheath can lead the cells to reconnect in the right direction.

“When they graft skin, it’s fairly easy to regrow cells, because the skin cells don’t have a direction in their growth pattern,” Gibson said.

Mallapragada also “seeded” Schwann cells into grooves of the polymer. The Schwann cells create a myelin sheath around the cells that helps stimulate growth. The in-vitro tests using the polymer showed promising results for nerve cell regrowth in the peripheral nervous system. The in-vitro tests showed nerves cells were able to grow efficiently with the aid of the polymer, Mallapragada said.

In her trial on laboratory rats, Mallapragada removed the rats’ sciatic nerve, causing the rats to lose the use of their legs. Three weeks after the addition of the polymer and Schwann cells to the severed nerves, the rats were able to use their legs again, and they were able to walk again after six weeks, she said.

“I think, as in a number of other areas, when they have success in tests in animals, there is hope it will be successful in humans,” said Kerry Gibson, communication specialist for the Ames Laboratory of the U.S. Department of Engineering. “It is the lab’s job to declare material and get a basic understanding [through research] and then haul it off to other research labs and areas.”

Mallapragada said there is no way of knowing yet if the success she had with rats will translate to humans. Mallapragada’s discovery in the peripheral nervous system has lead her to focus on the central nervous system, which includes the spinal cord, brain and optic nerve. She is currently focusing on the optic nerve, she said.

“I guess [the central nervous system] was always in the back of our heads,” she said. “We were happy with the way the peripheral nervous system turned out, so we moved to the central nervous system.”

There are challenges in the central nervous system that Mallapragada didn’t have to face working with the peripheral nervous system, Gibson said.

“In the central nervous system, the nerve cells grow differently,” he said. “There are a number of factors [that determine cell growth], not just being able to steer them.”

Gibson said there are chemical and electrical cues in the central nervous system cells that are not involved in peripheral nervous system cell regrowth.

“At this point, they don’t understand everything that takes place, but they are working on it,” Gibson said.