Striking a Nerve
Nanofibers that create a miniature scaffold for growing cells could soon help patients regenerate severed nerves in their arms and legs, says Shyam Patel (B.S. ’02, Ph.D. ’07 BioE).
Patel, chief scientific officer for a Fremont startup called NanoNerve, is developing a synthetic graft intended to guide neurons across gaps and restore lost connections in nerves serving limbs and other parts of the peripheral nervous system. In the United States alone, an estimated 800,000 people a year experience peripheral nerve injuries that require surgery and that can lead to a loss of sensation and movement. The new device—a flexible conduit that resembles a slender white straw—could open a new treatment option, says the 28-year-old Patel.
The graft is composed of a polymer, similar to the material in surgical sutures, engineered so its tiny fibers are aligned in the same direction. “Think of it as a stack of pencils all along one orientation,” says Patel, whose work builds on his doctoral research in the Stanley Hall lab of Song Li, associate professor of bioengineering. The aligned nanofibers appear to dramatically influence the growth of cells. In lab tests, Patel found that nerve tissue cultured on unaligned fibers showed little organized growth. In contrast, neurons on aligned material extended along the precise pattern of the fibers. “It’s a way of guiding them, almost like train tracks,” says Patel. “When nerve fibers feel it, they align themselves along it.”
Based on promising lab and animal studies, the company plans to seek FDA approval to start clinical trials on the grafts and institute a marketing plan as early as next year. Li, who cofounded NanoNerve in 2006, says the graft “could be the most efficient synthetic matrix ever made for nerve guidance.”
Current options for treating severed peripheral nerves have limitations. One approach calls for sacrificing another nerve, often a sensory nerve from the leg, to replace the damaged one. This involves additional surgery with potential complications. Furthermore, some patients don’t have suitable nerves to donate. Synthetic grafts are available, but Patel says these don’t guide cell growth and only bridge narrow gaps ranging from 5 millimeters to 3 centimeters long. Patel thinks the new device will outperform synthetic grafts and work at least as well as autografts harvested from other parts of the body.
He sees potential for even greater strides. Along with the discovery that the aligned fibers guide neurons, Patel found he could speed up growth by coating the nanofibers with bioactive molecules such as proteins or polysaccharides. In the lab, neurons on the coated material grew 4 millimeters over a five-day period. “It’s very fast and very organized,” says Patel, who thinks these growth factors could help neurons span longer gaps than now possible.
Patel hopes to start testing bioactive grafts in 2009. Such technology might one day provide a long-sought-after treatment for more severe spinal cord injuries, he says. Patel, who was originally drawn to bioengineering because of its real-world applications, has been working with nerve grafts since 2005. The project got its start when Li and his graduate students began studying the nanofiber scaffolds and quickly concluded the material might have therapeutic potential.
Patel’s work has been recognized as one of the Top 25 Micro/Nano Technologies of 2007 by R&D Magazine. The nanofiber graft placed third in the national Biomedical Engineering Innovation, Design, and Entrepreneurship Award (BMEidea) competition in 2007.
“It’s very exciting,” says Patel. “I’m working on something that will help a lot of patients.”