title: Comparison of osteoclastogenesis and resorption activity of human osteoclasts on tissue culture polystyrene and on natural extracellular bone matrix in 2D and 3D.
abstract: Bone homeostasis is maintained by osteoblasts (bone formation) and osteoclasts (bone resorption). While there have been numerous studies investigating mesenchymal stem cells and their potential to differentiate into osteoblasts as well as their interaction with different bone substitute materials, there is only limited knowledge concerning in vitro generated osteoclasts. Due to the increasing development of degradable bone-grafting materials and the need of sophisticated in vitro test methods, it is essential to gain deeper insight into the process of osteoclastogenesis and the resorption functionality of human osteoclasts. Therefore, we focused on the comparison of osteoclastogenesis and resorption activity on tissue culture polystyrene (TCPS) and bovine extracellular bone matrices (BMs). Cortical bone slices were used as two-dimensional (2D) substrates, whereas a thermally treated cancellous bone matrix was used for three-dimensional (3D) experiments. We isolated primary human monocytes and induced osteoclastogenesis by medium supplementation. Subsequently, the expression of the vitronectin receptor (αVβ3) and cathepsin K as well as the characteristic actin formation on TCPS and the two BMs were examined. The cell area of human osteoclasts was analyzed on TCPS and on BMs, whereas significantly larger osteoclasts could be detected on BMs. Additionally, we compared the diameter of the sealing zones with the measured diameter of the resorption pits on the BMs and revealed similar diameters of the sealing zones and the resorption pits. We conclude that using TCPS as culture substrate does not affect the expression of osteoclast-specific markers. The analysis of resorption activity can successfully be conducted on cortical as well as on cancellous bone matrices. For new in vitro test systems concerning bone resorption, we suggest the establishment of a 2D assay for high throughput screening of new degradable bone substitute materials with osteoclasts.
authors.affiliation: Institute for Interfacial Process Engineering and Plasma Technology IGVP, University of Stuttgart, Nobelstrasse 12, 70569 Stuttgart, Germany; Medical University Graz, Department of Orthopaedics, 8036 Graz, Austria.
authors.forename: C
authors.initials: C
authors.lastname: Kleinhans
authors.affiliation: Fraunhofer Institute for Interfacial Engineering and Biotechnology (IGB) , Nobelstrasse 12, 70569 Stuttgart, Germany.
authors.forename: F F
authors.initials: FF
authors.lastname: Schmid
authors.affiliation: Fraunhofer Institute for Interfacial Engineering and Biotechnology (IGB) , Nobelstrasse 12, 70569 Stuttgart, Germany.
authors.forename: F V
authors.initials: FV
authors.lastname: Schmid
authors.affiliation: Institute for Interfacial Process Engineering and Plasma Technology IGVP, University of Stuttgart, Nobelstrasse 12, 70569 Stuttgart, Germany; Fraunhofer Institute for Interfacial Engineering and Biotechnology (IGB) , Nobelstrasse 12, 70569 Stuttgart, Germany; Reutlingen University, Process Analysis & Technology (PA&T), Alteburgstraße 150, 72762 Reutlingen, Germany. Electronic address: petra.kluger@igb.fraunhofer.de.
authors.forename: P J
authors.initials: PJ
authors.lastname: Kluger
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D001857:Bone Matrix / Q000378:metabolism; D001862:Bone Resorption / Q000473:pathology; D002417:Cattle; D002454:Cell Differentiation; D048429:Cell Size; D006801:Humans; D009000:Monocytes / Q000166:cytology*; D010006:Osteoblasts / Q000166:cytology*; D010010:Osteoclasts / Q000166:cytology / Q000378:metabolism*; D011137:Polystyrenes / Q000494:pharmacology; D046509:Tissue Culture Techniques / Q000379:methods*
chemical_list: D015415:Biomarkers; D011137:Polystyrenes
keywords: Bone resorption; Cell–material interactions; Human monocytes; Osteoclastogenesis; Osteoclasts