Effects of extracorporeal shock waves on human articular chondrocytes and ovine bone marrow stromal cells in vitro

Introduction. We investigated the effects of extracorporeal shock waves on cytotoxicity and on the proliferation of human chondrocytes and ovine bone marrow stromal cells. Materials and methods. Isolated cells were cultured to confluence, and 500 shock waves were applied at energy flux densities of 0, 0.02, 0.06, and 0.17 mJ/mm(2) for the cytotoxicity assay. The same energies at 100, 500, and 1000 impulses were used for the proliferation assay. Results. Although bone marrow stromal cells revealed a dose- and impulse-dependent increase in the proliferation rate, no significant differences were found. Chondrocytes had less proliferative potential than untreated control groups. In the experimental set-up using 1000 impulses, proliferation was even higher in the control group. Both types of cells revealed a dose-dependent increase in cytotoxicity in the lactate dehydrogenase (LDH) assay. Conclusion. As femoral head necrosis, osteochondritis dissecans, and similar disorders are increasingly treated with shock waves, their effect on human cartilage and chondrocytes deserves attention. We recommend further in vitro experiments with bone marrow stromal cells, as the latter might play an important role in the presumed multifactorial osteogenetic mechanism of shock waves due to their pluripotent character.