Microcracks and Osteoclast Resorption Activity In Vitro

Author(s)

Monika Rumpler, Tanja Würger, Paul Roschger, Elisabeth Zwettler, Herwig Peterlik, Peter Fratzl, Klaus Klaushofer

Abstract

During bone remodeling osteoclasts resorb bone, thus removing material, e. g., damaged by microcracks, which arises as a result of physiological loading and could reduce bone strength. Such a process needs targeted bone resorption exactly at damaged sites. Osteocytic signaling plays a key role in this process, but it is not excluded that osteoclasts per se may possess toposensitivity to recognize and resorb damaged bone since it has been shown that resorption spaces are associated with microcracks. To address this question, we used an in vitro setup of a pure osteoclast culture and mineralized substrates with artificially introduced microcracks and microscratches. Histomorphometric analyses and statistical evaluation clearly showed that these defects had no effect on osteoclast resorption behavior. Osteoclasts did not resorb along microcracks, even when resorption started right beside these damages. Furthermore, quantification of resorption on three different mineralized substrates, cortical bone, bleached bone (bone after partial removal of the organic matrix), and dentin, revealed lowest resorption on bone, significantly higher resorption on bleached bone, and highest resorption on dentin. The difference between native and bleached bone may be interpreted as an inhibitory impact of the organic matrix. However, the collagen-based matrix could not be the responsible part as resorption was highest on dentin, which contains collagen. It seems that osteocytic proteins, stored in bone but not present in dentin, affect osteoclastic action. This demonstrates that osteoclasts per se do not possess a toposensitivity to remove microcracks but may be influenced by components of the organic bone matrix.

Organisation(s)

Dynamics of Condensed Systems

External organisation(s)

Ludwig Boltzmann Institute of Osteology, Max-Planck-Institut für Kolloid- und Grenzflächenforschung

Journal

Calcified Tissue International

Volume

90

Pages

230-238

No. of pages

9

ISSN

0171-967X

DOI

https://doi.org/10.1007/s00223-011-9568-z

Publication date

2012

Peer reviewed

Yes

Austrian Fields of Science 2012

106006 Biophysics

Portal url

https://ucrisportal.univie.ac.at/en/publications/microcracks-and-osteoclast-resorption-activity-in-vitro(8d73ff86-de6d-4d3e-b270-3cfce9e6e67c).html