As currently available tissue engineering strategies cannot fully regenerate hyaline cartilage, novel approaches are being tested, including the use of electrical stimulation to promote cartilage regeneration. A new study reports that use of a biodegradable piezoelectric scaffold in combination with physical exercise promotes chondrogenesis and cartilage regeneration in osteochondral defects in rabbits, suggesting it could have potential for the treatment of osteoarthritis.

Cartilage is known to be sensitive to electrical stimulation. The 3D scaffold used in the study is an assembly of piezoelectric poly(l-lactic acid) (PLLA) nanofibres that generate electricity under applied force, such as the force from exercise-induced joint motion. Implanted into damaged joints, the scaffold would thus serve as a battery-less electrical stimulator to accelerate cartilage growth.

In vitro, use of the piezoelectric PLLA scaffold and applied physical force promoted chondrogenic differentiation of rabbit adipose-derived stem cells. Further experiments showed the scaffold influenced chondrogenesis by attracting extracellular matrix proteins, triggering calcium ion influx and inducing secretion of TGFβ by the stem cells.

In vivo, the piezoelectric scaffold was implanted into critical-sized osteochondral defects in rabbit knees. Rabbits treated with treadmill exercise for 1–2 months (after a 1-month recovery period) had substantial healing and hyaline cartilage regeneration in the defects, with abundant chondrocytes and expression of type II collagen; subchondral bone volume was also increased. By contrast, rabbits treated with non-piezoelectric scaffolds and exercise, or with piezoelectric scaffolds and no exercise, had less regeneration and limited healing.

Further studies will seek to elucidate the mechanisms by which the scaffold achieves cartilage regeneration, as well as optimize the exercise regimen and the functional life of the biodegradable scaffold.