The insulin-like growth factor I (IGF-I) has an anabolic effect in chondrocyte metabolism. Amongst others, IGF-I increases the synthesis of proteoglycan. Previous studies (for example: De Mattei et al., 2004, De Mattei et al., 2001) indicated a similar effect induced by low frequency pulsed electromagnetic fields. To further examine this hypothesis, cartilage samples were exposed and treated with IGF-I and interleukin-1ß (IL-1ß, plays a role in cartilage destruction, suppresses the synthesis of proteoglycan) alone or in combination for 1 or 7 days.
Human cartilage samples were obtained from 13 patients with knee osteoathritis undergoing total knee replacement. The stage of osteoarthritis was scored and the cartilage samples were classified. The samples with slight degenerations were obtained from all patients, while the severe cartilage degeneration samples were obtained from only 4 patients.
|Chamber||a pair of circular Helmoltz coils made of copper wire, placed opposite to each other and in a signal generator; multiwell plates were placed between this pair of Helmoltz coils so that the plane of the coils was perpendicular to the multiwell plates|
|Sham exposure||A sham exposure was conducted.|
After 7 days, PEMF exposure or IGF-I treatment alone led to a significant increase in the synthesis of proteoglycan in comparison to the control samples, while a combination of exposure and IGF-I treatment significantly increased the amount of proteoglycan synthesis. After 1 day of incubation, only the combination of exposure and IGF-I increased the proteoglycan synthesis in the cartilage explants significantly in comparison to the control. No significant changes in the proteoglycan release in the culture medium by PEMF exposure or IGF-I addition were observed.
After 7 days of incubation, treatment with IL-1ß led to a significant decrease in proteoglycan synthesis in comparison to the control. This effect was significantly attenuated by exposure or IGF-I treatment and even more by a combination of both when a concentration of 0.01 ng/ml IL-1ß was used. No PEMF exposure- or IGF-I-related effects were seen when the concentration of IL-1ß was 10 ng/ml. No significant differences in the lactate production in the culture media at all IL-1ß doses were found compared to the control group.
The authors conclude that pulsed electromagnetic fields could have a chondroprotective effect on human cartilage, especially in combination with IGF-I.