In vitro and in vivo assays for osteoclast apoptosis

Mature osteoclasts, multinucleated giant cells responsible for bone resorption, are terminally differentiated cells with a short life span. Recently, we have demonstrated that osteoclast apoptosis is regulated by ERK activity and Bcl-2 family member Bim. In this paper, we summarize the methods we used to study osteoclast apoptosis in vitro and in vivo . Using adenovirus and retrovirus vectors, we were able to introduce foreign genes into osteoclasts and examine their effects on osteoclast survival in vitro . In addition, we established the modified methods for in situ hybridization and BrdU labeling of bone sections from mice to study osteoclast survival in vivo . The detailed methods described here could be useful for studying the biological process in bone.