Regular electrical pulses delivered to damaged peripheral nerves in rats after surgical repair accelerate the regrowth of nerves in their legs and enhance recovery of muscle strength and control. The wireless device, which is the size of a dime and the thickness of a sheet of paper, operates for about two weeks before naturally absorbing into the body, according to materials scientists and engineers at Northwestern University who developed the stimulating device with neurosurgeons at Washington University’s School of Medicine.
“These engineered systems provide active, therapeutic function in a programmable, dosed format and then naturally disappear into the body, without a trace,” says Northwestern’s John A. Rogers, a pioneer in bio-integrated technologies and a co-senior author of the study.
While the device has not been tested in humans, the findings offer promise as a future therapeutic option for nerve injury patients.
“We know that electrical stimulation during surgery helps, but once the surgery is over, the window for intervening is closed,” says co-senior author Dr. Wilson “Zack” Ray, an associate professor of neurosurgery, biomedical engineering, and orthopedic surgery at Washington University. “We’ve shown that electrical stimulation given on a scheduled basis can further enhance nerve recovery.”
Throughout the past eight years, Rogers and his lab have developed a collection of electronic materials, device designs, and manufacturing techniques for biodegradable devices to address unmet medical needs. When Ray and his colleagues at Washington University identified the need for electrical stimulation-based therapies to accelerate wound healing, Rogers and colleagues at Northwestern went to their toolbox and set to work.The experimental thin, flexible device wraps around an injured nerve and delivers electrical pulses at selected times for days before the device harmlessly degrades in the body. A transmitter outside the body, much like a cellphone-charging mat, powers and wirelessly controls the implant.
Washington University researchers then studied the bioelectronic device in rats with injured sciatic nerves. The device provided one hour per day of electrical stimulation to the rats for one, three, or six days or no electrical stimulation at all, and then monitored their recovery for the next 10 weeks.
They found that any electrical stimulation was better than none for helping rats recover muscle mass and strength. The more days of electrical stimulation, the quicker and more thoroughly they recovered nerve signaling and muscle strength. They found no adverse biological effects from the device or its reabsorption.
By varying the composition and thickness of the materials in the device, Rogers and colleagues can control the precise number of days it remains functional before being absorbed into the body. New versions can provide electrical pulses for weeks before degrading.
The research study also showed the device can work as a temporary pacemaker and as an interface to the spinal cord and other stimulation sites across the body. These findings suggest broad utility beyond the peripheral nervous system.
Washington University School of Medicine