Implantable Ion Pump Helps Body Alleviate Pain

A new study describes an innovative organic electronic ion pump that can impede pain impulses by using the body’s own neurotransmitter signals.

Developed by researchers at Linköping University (LiU; Sweden) and the Karolinska Institutet (KI; Solna, Sweden) the small ion pump consists of an electronically and ionically conducting polymer electrode inside a fluid reservoir, and an ionically conducting delivery channel leading out to the target region, such as the spinal cord. The reservoir is filled with a solution of drugs, neurotransmitters, or other therapeutic substances. When a voltage is applied between the internal and external counter electrodes, the substances are electrophoretically transported out of the reservoir.

The substances thus pumped correspond directly to the individual electronic current delivered through the control hardware; only the intended substance is transported, no liquid is transported, and there is no backwards flow from the target region. For example, pain impulses can be blocked from reaching the brain by delivering the neurotransmitter γ-aminobutyric acid (GABA), whose natural task is to inhibit stimuli in the central nervous system (CNS), to the target area.

The technological breakthrough that the researchers achieved was constructing the therapeutic implant using organic electronics, a class of materials capable of easy translation between electronic and biochemical signals. The researchers used the ion pump to block pain impulses in awake, freely-moving rats, using an electric current that caused GABA to spread as a thin cloud at four different locations on the spinal cord. The resulting pain alleviation had no negative side effects. The study describing the system was published in the May 2015 issue of Science Advances.

“The ion pump can be likened to a pacemaker, except for alleviating pain,” said Prof. Magnus Berggren, PhD, of the LiU laboratory of organic electronics. “While a pacemaker sends electrical impulses to the heart, the ion pump sends out the body’s own pain alleviator—charged molecules of what are known as neurotransmitters—to the exact place where the damaged nerves come into contact with the spinal cord.”

An ion pump moves ions across a plasma membrane against their concentration gradient, in contrast to ion channels, where ions go through passive transport.

Related Links:
Linköping University
Karolinska Institutet
The organic electronic ion pump video