The effects of direct current stimulation on isolated chondrocytes seeded in 3D agarose constructs.

Endogenous electrical activity has been detected in articular cartilage. It has previously been suggested that the associated electrical currents and potentials are important to the mechanotransduction processes in cartilage. The present study investigates the effects of direct current on cell proliferation and matrix synthesis, using the well established 3D chondrocyte--agarose model system. Bovine chondrocytes isolated from metacarpalphalangeal joints were seeded in agarose constructs and exposed to a current density of 4 mA/cm2 for 6 h, a magnitude and period which was shown to maintain cell viability. The influence of the optimized electric stimulus was assessed by protein incorporation and mRNA measurements, using radiolabels and real-time QPCR, respectively. Results indicated no systematic influences of electrical current on protein synthesis, cell proliferation and mRNA expression levels. These data suggest that both the mode of stimulation and the model system are critical for the in vitro modulation of chondrocyte metabolism.