We've already heard about implantable materials with a scaffolding-like microstructure, that help heal broken bones by giving bone cells a place to migrate into. A new one could work even better, though, by also providing electrical stimulation.
Scientists have previously had success using implants to mimic the body's own electrical field, stimulating bone cells into reproducing. Unfortunately, though, these devices have tended to be bulky, requiring an integrated (potentially toxic) battery or a hard-wired external power source. Additionally, once the broken bone has healed, the implants have to be surgically removed.
Led by biomedical engineer Thanh Nguyen, scientists at the University of Connecticut have instead developed an electrified scaffold material which is wirelessly powered, and that never has to be taken out. It's made of nanofibers of a non-toxic, piezoelectric polymer known as poly(L-lactic acid) or PLLA – piezoelectric materials produce an electrical charge in response to applied mechanical stress.
The idea is that after the material was implanted at a bone fracture site, the doctor or even the patient would periodically use an external handheld device to send pulses of ultrasound through to it. Those pulses would cause the scaffolding to vibrate, with the stress from those vibrations in turn causing it to generate a weak but therapeutic electrical field.
As the body's stimulated bone cells proceeded to reproduce within the scaffolding, it would gradually and harmlessly dissolve. Eventually the material would be entirely replaced with natural bone, so nothing would need to be removed.
In tests conducted so far, the material has been used to boost the healing of skull fractures in mice. The scientists are now working on making the scaffolding more favorable to bone growth, and on gaining a better understanding of exactly how electrical fields stimulate bone cells to reproduce. Ultimately, it is hoped that the technology could also help to regrow other types of tissue, such as muscles, nerves or cartilage.
A paper on the research was recently published in the journal Nano Energy.
Source: University of Connecticut via EurekAlert