PEMF effects on chondrocyte cellularity and gene expression of the rat distal femoral metaphyseal articular cartilage

Abstract

the purpose of the current study was to determine the effect of PEMF on the rat distal femoral joint cartilage, in terms of chondrocytic gene expression level and cellularity. 20 Wistar female rats from two litters were randomly distributed in two groups: 10 rats (Stimulated Group) received PEMF (1 Hz, 30 mT/30 min per day/20 days in a row); the other 10 animals (Control Group) received similar treatment, with the difference that the electromagnetic stimulation was turned off. After the experimental intervention, thin histological sections were analyzed under Clear Field Microscopy in order to quantify chondrocytic cellularity. In addition, specific chondrocyte proteins expression was measure. Statistically significant differences were found in joint cartilage cellularity when MS and Non-MS were compared (101.13 ± 25.61 vs. 69.66 ± 15.55 cells per optical field, respectively; p=0.001). Collagen XI, Sox6 and Aggrecan expression levels were also different in magnetically stimulated tissues relative to control. On the other hand RUNX2 and ALPL expressions showed no significant differences between groups (X-squared test p < 0.05). These results are evidence that in vivo PEMF stimulation increases the number of well differentiated knee joint cartilage cells in healthy young adult rats. The low gene expression of RUNX2 and ALPL supports that the chondrocytic response to PEMF do not correspond to a hypertrophic reaction. These results highlight the possible therapeutic future of PEMF in cartilage injuries, and on its ageing.