Intrduction:

Osteoarthritis (OA) is one of the most common rheumatic diseases directly involving the articular cartilage.  The biomechanical properties of the cartilage depend upon the extracellular matrix produced by the chondrocytes, cells which are capable of maintaining a dynamic equilibrium between the anabolic and catabolic processes.  The metabolic activity of these cells is regulated by several mediators, such as cytokines, hormones and growth factors.  Interleukin 1 (IL-1ß) is a cytokine involved in cartilage degradation processes.  It is produced by several types of cells and can be found in the synovial fluid of osteoarthritic subjects. 

The clinical use of Pulsed Signal Therapy (PST ™) has proven effective in the treatment of 70,000 patients suffering from osteoarthritis. To explain this efficacy, it is hypothesized that the PST-induced Faradic potentials serve to mimic intrinsic pressure-generated streaming potentials.

In this work we have studied the in vitro effects of PST on cultures of human articular chondrocytes cultivated in the presence or in the absence of IL-1ß Under these conditions we studied the effect of PST through metabolic activity evaluated by proteoglycans (PG) levels in the culture medium and morphologic assessments carried out with a transmission electron microscope (TEM) and a scanning electron microscope (SEM).

Materials and Methods:

Human articular cartilage was obtained from the femoral heads of eight OA subjects undergoing surgery for total hip prostheses. Immediately after surgery, macroscopically healthy cartilage were cut aseptically and minced into 2-mm² pieces. The cartilage fragments were washed in saline solution and then digested by clostridial collagenase.

Chondrocytes were cultivated in alginate gel on Petri dishes for 72 hours with and without IL-1ß (5ng/ml). Some dishes were exposed for 3 hours a day to PST. Control cultures were maintained under identical conditions to the treated cells, but in the absence of PST. After the culture period the medium was removed and collected for PG determination by immunoenzymatic method on microplates for the quantitative measurement of human PG. Cells in alginate gel were immediately fixed for transmission electron microscopy (TEM) and for scanning electron microscopy (SEM).

The data were expressed as the mean ±SD of PG release into the culture medium per micrograms of DNA in the eight tested cultures. The Student's test was used for the statistical analysis; p<0.05 was considered significant. When data were not normally distributed, the Mann-Whitney U test was used.