Inhibition of human in vitro osteoclastogenesis by Equisetum arvense.

OBJECTIVES: Equisetum arvense has long been used in traditional medicines to treat different disorders, including bone pathologies. In this study a hydromethanolic extract of E. arvense was assessed for its effects on human osteoclastogenesis.
MATERIALS AND METHODS: Osteoclast precursors were maintained in non-stimulated and stimulated (presence of M-CSF and RANKL) conditions, or in co-cultures with osteoblasts. Cell cultures were treated with 0.00016-0.5 mg/ml of a hydromethanolic E. arvense extract.
RESULTS: The extract did not affect spontaneous osteoclastogenesis. In osteoclast precursors committed to osteoclastogenesis (stimulated or co-cultured with osteoblasts), E. arvense caused dose-dependent inhibitory effect that became statistically significant at concentrations ≥0.004 mg/ml. This was observed using different osteoclast differentiation and activation markers. Cell response was associated with changes in relative contribution of MEK and NFkB signalling pathways, as well as PGE2 production. As there were differences in the response of osteoclast precursors maintained in the presence of inductive factors, or co-cultured with osteoblastic cells, it seems that E. arvense extract had the ability to modulate osteoclastogenesis, either by acting directly on osteoclast precursor cells, and/or via osteoblasts.
CONCLUSIONS: Equisetum appeared to have a negative effect on human osteoclastogenesis, which is in line with its putative beneficial role in pathophysiological conditions associated with increased osteoclastic activity, and might suggest potential utility for treatment with bone regeneration strategies.