A team of researchers from the University of Connecticut has developed a biomaterial scaffold that generates small amounts of electricity when squeezed. The piezoelectric material is said to facilitate cartilage regeneration in joints. The normal movement of a joint in which the scaffold is implanted creates repeated small surges of electricity. Researchers theorize that this electrical charge is a key component of cartilage healing and helps attract cells that settle and grow within the scaffold.
Cartilage regeneration is a highly active research area in regenerative medicine and tissue engineering. This is because it wears out relatively easily (especially the cartilage that lines our joints), doesn’t heal very well, and is difficult to regenerate. Therefore, cartilage is a prime candidate for new and disruptive regenerative medical technologies.
To date, researchers have tried all sorts of approaches to regrow cartilage, including growth factors and cells injected into biomaterial scaffolds. However, the newly regenerated tissue does not always behave as desired. “The regrown cartilage does not behave like native cartilage. It breaks under the normal stresses on the joint,” said Thanh Nguyen, one of the UConn researchers involved in the study.
Nguyen and colleagues have identified electricity as a previously understudied factor in cartilage regeneration that could aid in the regeneration process. They decided to explore piezoelectric materials that can generate electricity in response to mechanical deformation, a process they believe already occurs in the body. “Piezoelectricity is a phenomenon that also exists in the human body,” said Yang Liu, another developer of the new technology. “Bones, cartilage, collagen, DNA and various proteins have a piezoelectric response. Our approach to healing cartilage is highly clinically transferable and we will study the associated healing mechanism.”
Researchers fabricated an implantable scaffold from poly-L-lactic acid (PLLA) nanofibers and implanted it into rabbits with injured knee cartilage. The PLLA material is typically used to sew up surgical incisions and it is also biodegradable and therefore will eventually degrade allowing the new cartilage to replace it. It’s also piezoelectric, so it needs movement to generate electricity.
The researchers allowed the rabbits to use a treadmill to encourage movement and generate electricity within the injured cartilage. They observed that the treated rabbit knees showed robust cartilage regeneration and the new cartilage appeared to be mechanically strong and resistant to degradation with normal movement.
Watch a video of one of the rabbits hopping on a treadmill after implantation (why not?)
Studies in scientific translational medicine: Stress-induced piezoelectric stimulation for cartilage regeneration in rabbits
