Polymer power for tissue engineering

Polymers that conduct electricity to stimulate cells and monitor their natural electrical activity could be useful in medicine.

“Our bodies are electrical,” says . She is discussing the development of biocompatible and biodegradable electrically  to stimulate and monitor cells and tissues.

Cartmell, at , and her colleagues Nigel Cassidy and Richard Balint, reviewed the development of conductive polymers for tissue engineering applications in the journal . Their review has become one of the journal's most downloaded articles, reflecting wide interest.

 covers a wide range of methods for modifying cells and tissues. These modifications can potentially repair or replace diseased or damaged parts.

Many research groups are already exploring tissue engineering methods on laboratory animals and humans. Cartmell and her colleagues focused on the fundamental in vitro work on cells and tissues needed to support in vivo research.

In her current work, Cartmell has demonstrated that electrical stimulation can promote stem-cell proliferation and bone formation. "For tissue-engineering purposes this is very exciting,” she says.

One key aim of the worldwide research effort is to use electrical stimulation to generate modified tissues grown on polymer scaffolds. These are designed to be implanted into the body, and could be used for a number of purposes: as neural implants to repair nerve damage in the brain, for example, or to fix major nerve systems involved in paralysis.

Electrical stimulation can promote the branching of nerve cells to help nerves repair themselves. It can also be used in drug-delivery systems, where an external electrical stimulus is used to release the drug into the affected system.

This research can also generate . These can report on the status of body tissues by sending electrical signals to clinicians monitoring the condition's progress and its response to treatment.

Such applications all depend on developing a suitable pathway for electrical signals, either applied to, or received from, cells and tissues. This would traditionally involve metal wires but developing carbon-based polymers to carry the signals offers many key advantages. Such polymers can be biocompatible and biodegradable. Researchers can tailor them to different applications by chemically modifying the basic polymer structure, or by incorporating bio-active molecules such as drugs and antibodies.

The problem with polymers is that many of them do not conduct electricity. In this review, the authors highlight the development of three specific categories of conductive polymers: polypyrroles, polyanilines and polythiophenes. They consider the chemical procedures that create suitable polymers and control their electrical activity.

"Since our review was published we have seen the development of new biocompatible composites and many other advances," Cartmell reports. She says that researchers are now looking at the molecular mechanisms involved in the responses of cells to electrical stimulation. Other advances are steadily improving the production methods of the conductive materials and reducing their cost.

“These smart biomaterials and tissue engineering strategies may eventually offer innovative solutions to many current clinical problems,” Cartmell concludes.-

-Cartmell, S. H., et al.: "," Acta Biomaterialia (2014)

Acta Biomaterialia is part of the family of Acta Materialia Inc journals, which also includes Acta Materialia, Scripta Materialia and the newly launched Materialia.