The effect of purmorphamine on murine osteoclast activity

Abstract

Aims The aim of the study was (i) to establish and characterize a model to evaluate the effect of purmorphamine on murine osteoclastic activity; (ii) to test the hypothesis that purmorphamine‐stimulated osteoclasts would resorb test calcium phosphate surfaces more than controls. The alternative hypothesis was that purmorphamine‐stimulated osteoclasts would be associated with significantly less resorption than baseline controls.Methodology In the characterization phase, cultured osteoclasts were able to resorb a calcium phosphate coating (CaP) allowing a simple but effective model to assay their activity. Bone marrow from 50 neonatal mice provided the source of osteoclasts that were seeded onto 100 CaP‐coated discs to evaluate the effect of purmorphamine on their activity. Culture medium was used as a baseline control and bisphosphonate as negative control.Results The characterization phase of the study demonstrated that a suitable CaP coating could be reproducibly precipitated onto the discs and that resorption through the action of TRAP‐positive, multi‐nucleate cells was quantifiable. Bisphosphonate negative controls showed no resorption. From a starting sample of 100 CaP discs, attrition through development and infection problems left five experiment and control pairs, the analysis of which showed that purmorphamine‐stimulated osteoclasts were associated with significantly (P = 0.043) less resorption than baseline controls, indicating that it probably had an inhibitory effect on osteoclast function.Conclusions Purmorphamine is an important bone agonist that could possibly be combined with grafting materials and induce bone regeneration. Within the limitations of the study, it can be concluded that purmorphamine does not induce differentiation of precursors into osteoclasts, supporting the alternative hypothesis. The next step would be to evaluate the properties of purmorphamine in conjunction with grafting materials (e.g. hydroxylapatite) by using implantation and usage tests in animals. In this way, the effect of purmorphamine on bone regeneration can be assessed and conclusions about its usefulness can be drawn.