The researchers aimed to overcome the shortcomings of existing robotic prosthetics, which have only limited motor control, provide no sensory feedback and can be uncomfortable and cumbersome to wear. “Most of these individuals are typically using a prosthesis design that was developed decades ago,” Paul S. Cederna, one of the principal investigators, said. “This effort is to make a prosthesis that moves like a normal hand.”
When a hand is amputated, the nerve endings in the arm continue to sprout branches, growing a mass of nerve fibers that send flawed signals back to the brain. The researchers created what they called a “bio-artificial neuromuscular junction,” composed of muscle cells and a nano-sized polymer placed on a biological scaffold. Neuromuscular junctions are the body’s own nerve-muscle connections that enable the brain to control muscle movement.
That bioengineered scaffold was placed over the severed nerve endings like a sleeve. The muscle cells on the scaffold and in the body bonded and the body’s native nerve sprouts fed electrical impulses into the tissue, creating a stable nerve-muscle connection. In laboratory rats, the bioengineered interface relayed both motor and sensory electrical impulses and created a target for the nerve endings to grow properly.
The results in laboratory rats indicate the interface may not only improve fine motor control of prostheses, but can also relay sensory perceptions such as touch and temperature back to the brain. Laboratory rats with the interface responded to tickling of feet with appropriate motor signals to move the limb, according to Cederna. The research team has submitted a proposal to the Defense Advance Research Project Agency to begin testing the bioengineered interface in humans in three years.
MEDICA.de; Source: American College of Surgeons (ACS)