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AB0626 Non-invasive optical detection of cathepsin k-mediated fluorescence reveals osteoclast activity in mouse model of osteoporosis
  1. S. Choi1,1,
  2. A. Lee1,
  3. Y. H. Seo1,
  4. Y. H. Lee1,
  5. J. D. Ji1,
  6. G. G. Song1
  1. 1KOREA UNIVERSITY MEDICAL CENTER RHEUMATOLOGY, Ansan, Korea, Republic Of

Abstract

Background Osteoporosis is a skeletal disorder characterized by bone strength to an increased risk of fracture. It becomes an important public health issue, because of the ageing population. Osteoporosis imaging is important to identify individual at risk for fractures to reduce fracture and also monitoring response to treatment.

Objectives Imaging modalities such as DXA, X-ray and pQCT report bone density. The development of image-based indicators of osteoclast activity will provide for early identification of changes in bone resorption. Individualized treatment was based on early detection of osteoclast activity.

Methods Our team developed osteoclast specific smart nanoparticle (Cathepsin K target nanoprobe). Osteoclasts are one of the major source of cathepsin K. Cathepsins are a group of 11 enzymes belonging to the papain family of cysteine proteases. Especially, cathepsin K is known to play an important role in bone resorption in osteoporosis. Therefore, cathepsin K is an attractive target enzyme for both diagnosis and treatment of osteoporosis. Furthermore, in vivo imaging of cathepsin K could be used to detect biological activities related with progressive osteoporosis and to monitor therapeutic responses to drugs or inhibitors.

Results We investigated a NIRF (near infrared fluorescent) smart nanoparticle which was activated by cathepsin K is shown in live osteoclast activity in mouse models of osteoporosis. In ovariectomized mice, cathepsin K probe intensity was detected very early time before any signs of structural or anatomic changes could be detected by the histologic and micro-CT analyses.

Conclusions These results may provide valuable meanings for early diagnosis of upregulated resorption and rapid feedback on efficacy of treatment protocols prior to significant bone loss in the patients at risk.

Disclosure of Interest None Declared

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