Non-invasive optical detection of cathepsin K-mediated fluorescence reveals osteoclast activity in vitro and in vivo.

ABSTRACT: Osteoclasts degrade bone matrix by demineralization followed by degradation of type I collagen through secretion of the cysteine protease, cathepsin K. Current imaging modalities are insufficient for sensitive observation of osteoclast activity, and in vivo live imaging of osteoclast resorption of bone has yet to be demonstrated. Here, we describe a near-infrared fluorescence reporter probe whose activation by cathepsin K is shown in live osteoclast cells and in mouse models of development and osteoclast upregulation. Cathepsin K probe activity was monitored in live osteoclast cultures and correlates with cathepsin K gene expression. In ovariectomized mice, cathepsin K probe upregulation precedes detection of bone loss by micro-computed tomography. These results are the first to demonstrat

SUBMITTER: Kozloff KM 

PROVIDER: S-EPMC2656637 | biostudies-literature | 2009 Feb

REPOSITORIES: biostudies-literature