gms | German Medical Science

Objectives: Osteoarthritis (OA) is the most common degenerative disease of the musculoskeletal system. Sufficient therapy of degenerated cartilage is not possible, since mature cartilage has a limited capacity for intrinsic repair. OA is a progressive disease with increasing functional impairment of the joints. Whole body vibration (WBV) is suggested to have a beneficial influence on OA patients' knees in terms of pain, stiffness and physical functions. A mouse OA model was used to assess WBV induced changes in muscle structures and changes on inflammation markers in serum.

Methods: To induce OA in 11-12 weeks old C57BL/6J mice the meniscotibial ligament of the right hind limb was dissected leading to a dislocation of the medial meniscus (DMM). The left hind limb served as a contralateral control. After one week, WBV training was started (15min/day, 7 weeks, 15 Hz, 0.3g). OA induced, non-vibrated mice served as a control. A standardized OARSI Scoring System was used to quantify changes in the knee joint. Muscle fiber specific cross sectional areas (CSA) were analyzed to measure the WBV effect on hind limb muscle fibers using immunofluorescence staining of serial histological sections. Furthermore, real-time detection (RTD)-PCR targeting genes of the muscle metabolism was performed. Raybio mouse cytokine antibody arrays C1000 were accomplished for OA induced mice with or without WBV and sham operated animals to detect changes in blood cytokine levels.

Results and conclusion: After WBV treatment, histological scoring and osteophyte formation showed no differences between both groups (with or without WBV). Both developed OA in DMM induced knees. Muscle fiber specific CSA revealed slightly increased fiber diameters in the anterior part of the vastus intermedius, but not in the posterior, lateral and medial area in the WBV treated group. RTD-PCR of the whole vastus intermedius showed no significant changes in gene expression of anabolic and catabolic muscle fiber metabolism genes between OA-induced and contralateral limbs with or without WBV. Mouse cytokine antibody arrays of blood serum 8 weeks after DMM surgery revealed that cytokines associated with OA were higher in serum samples of DMM induced mice without WBV than in sham controls. Furthermore, OA mice with WBV induction led to a reduction of most serum cytokines (e.g. Tumor necrosis factor α, Interleukin1β). Other proteins, like Insulin-like growth factor (IGF)1 were increased in serum from sham operated mice and OA induced mice with WBV.

The DMM model is suitable as an OA model in mice. WBV has influence only on the anterior part of the vastus intermedius considering CSA measuring of muscle fibers and no influence on gene expression of the whole vastus intermedius. Nevertheless WBV has an influence on blood cytokine levels leading to a decrease of several OA induced inflammatory cytokines and an increase of other proteins like IGF1. Mechanisms and reasons of the WBV induced serum cytokine changes are still unclear and have to be investigated.