A group of researchers from the University of Connecticut (USA) has managed to reconstruct the cartilage of a rabbit’s knee thanks to a kind of scaffold made of a nanomaterial with piezoelectric properties, that is, with the property of generating a electrical charge under mechanical stress.
This discovery, which has been published in the journal Science Translational Medicine, represents an advance in the treatment of problems in human joints, for example, in the case of rheumatoid arthritis. This disease generates pain due to joint damage, such as the wear of the cartilage pads. Current treatments consist of grafting a healthy piece of cartilage from another part of the body, however, they are complex procedures that can lead to rejection.
Attempts have also been made to grow new, healthy cartilage in the area by amplifying chemical growth factors or by creating a bioengineered scaffold to provide a template for fresh tissue to the body. However, none of these approaches have worked, as the regenerated cartilage was broken down by the normal stresses of the joint.
A tissue scaffold made from a biodegradable polymer
Now, researchers have created a tissue scaffold made from poly-L-lactic acid (PLLA) nanofibers, a biodegradable polymer often used to suture surgical wounds. This nanomaterial has a very interesting property, called piezoelectricity, which means that when it is squeezed, it produces a small burst of electric current.
The piezoelectric scaffold was placed on the knee of the injured rabbit and made to walk, the researchers observed that the cartilage grew normally.
Natural movement of a joint, such as walking, can cause the PLLA scaffold to produce a weak but constant electrical field that encourages cells to colonize it and become cartilage. In this way, the cartilage that grows is robust and no external growth factors or stem cells are needed, which experts explain are potentially toxic or at risk of unwanted adverse effects.
The tests were done on an injured rabbit, which after placing the PLLA scaffolding made it walk on an exercise treadmill. The results showed that the cartilage grew back normally. “Piezoelectricity is a phenomenon that also exists in the human body. Bone, cartilage, collagen, DNA, and various proteins have a piezoelectric response,” says Yang Liu, lead author of the study.
However, this effect should be further investigated with larger and heavier animals, which would be more similar to a human being. In addition, they will continue to observe the treated animals to see if the effect on cartilage is long-lasting and will test the PLLA scaffold in older animals, as arthritis is often a disease of old age.
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