An in vivo assay for osteoclast activity using mouse calvaria.

Osteoclasts are essential for maintaining healthy bone. Pathological elevation of osteoclastogenesis or osteoclast activity can cause osteoporosis and increase the risk of bone fracture. However, a few options are available for directly measuring osteoclast activity in vivo to test interventions that may affect osteoclasts. Here, we describe an in vivo method to measure osteoclast-mediated bone loss targeted at normal mouse calvaria. The method employs a novel procedure for measuring osteoclast resorption pits using micro-computed tomography. The potential utility of this mouse calvaria model to assess therapies targeting osteoclasts was validated using zoledronic acid, which is a nitrogen-containing bisphosphonate drug used to treat osteoporosis.