Electrical stimulation of regeneration
Professor Xudong Wang from the University of Wisconsin-Madison and his colleagues wondered if it was possible to speed up bone recovery after fractures using electricity.
It is known that electrical stimulation can accelerate the regeneration of bone tissue, but the restoration of bones after fractures using electricity has never been used in practical medicine, since this requires surgical implantation and removal of electrodes powered from an external source.
Wang and his colleagues described a new thin and flexible self-powered device that dissolves on its own and is safely removed from the body as soon as the bone defect is restored.
When placed over a fracture, the device generates electricity from movement, accelerating bone healing.
Bone is a piezoelectric material, that is, it produces electricity under mechanical pressure. These electrical impulses stimulate factors that promote bone growth and healing.
There are external stimulators that create an electric field to accelerate healing indirectly, but the ideal solution is direct bone stimulation. Installing the device inside the body requires solving some difficulties, in particular, the power supply.
Researchers have built a triboelectric nanogenerator placed on a thin film with a microstructural surface that converts mechanical energy produced by movements into electrical energy. They connected two wires to the nanogenerator in order to distribute the electric field over the bone. All components are biodegradable and bioresorbable, they consist of poly (lactic-co-glycolic acid), a widely used biocompatible polymer approved by the FDA.
Preliminary tests have confirmed that small movements of the device actually generate electrical energy of about 4 volts, which can last for more than six weeks. The device was then tested on rats.
These animals fully recovered after a tibial fracture in about six weeks – much faster than the animals of the control group. In rats receiving electrical stimulation, the mineral density and flexural strength of healed bones reached the same level as healthy bones. After treatment, the devices decomposed and were removed from the body without any complications and the need for surgical removal.
There are some problems in making the fracture electrical stimulation device work in humans. So, the energy source needs to be seriously modified, since usually in case of a fracture, patients are recommended to limit motor activity. In other words, someone who wears plaster will not be able to produce enough mechanical energy to power a triboelectric nanogenerator. As one of the ways to solve the problem of the power supply, the authors consider a device that responds to changes in pressure in blood vessels.
Article G.Yao el al. A self-powered implantable and bioresorbable electrostimulation device for biofeedback bone fracture healing is published in the journal PNAS.
Aminat Adzhieva, portal "Eternal Youth" http://vechnayamolodost.ru according to the University of Wisconsin–Madison: Self-powered implantable device stimulates fast bone healing, then disappears without a trace.