title: Giant crystals inside mitochondria of equine chondrocytes.
abstract: The present study reports for the first time the presence of giant crystals in mitochondria of equine chondrocytes. These structures show dark contrast in TEM images as well as a granular substructure of regularly aligned 1-2 nm small units. Different zone axes of the crystalline structure were analysed by means of Fourier transformation of lattice-resolution TEM images proving the crystalline nature of the structure. Elemental analysis reveals a high content of nitrogen referring to protein. The outer shape of the crystals is geometrical with an up to hexagonal profile in cross sections. It is elongated, spanning a length of several micrometres through the whole cell. In some chondrocytes, several crystals were found, sometimes combined in a single mitochondrion. Crystals were preferentially aligned along the long axis of the cells, thus appearing in the same orientation as the chondrocytes in the tissue. Although no similar structures have been found in the cartilage of any other species investigated, they have been found in cartilage repair tissue formed within a mechanically stimulated equine chondrocyte construct. Crystals were mainly located in superficial regions of cartilage, especially in joint regions of well-developed superficial layers, more often in yearlings than in adult horses. These results indicate that intramitochondrial crystals are related to the high mechanical stress in the horse joint and potentially also to the increased metabolic activity of immature individuals.
authors.affiliation: Department of Trauma Surgery, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria. sylvia.nuernberger@meduniwien.ac.at.|Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, AUVA Research Center, Donaueschingenstrasse 13, 1200, Vienna, Austria. sylvia.nuernberger@meduniwien.ac.at.|University Clinic of Dentistry, Medical University of Vienna, Sensengasse 2a, 1090, Vienna, Austria. sylvia.nuernberger@meduniwien.ac.at.|Austrian Cluster for Tissue Regeneration, Vienna, Austria. sylvia.nuernberger@meduniwien.ac.at.
authors.forename: S
authors.initials: S
authors.lastname: Nürnberger
authors.affiliation: Physics of Nanostructured Materials, Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria.
authors.forename: C
authors.initials: C
authors.lastname: Rentenberger
authors.affiliation: Department of Adhesive Bonding Technology and Surfaces, Fraunhofer Institute for Manufacturing Technology and Advanced Materials, Wiener Strasse 12, 28359 Bremen, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Thiel
authors.affiliation: Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, AUVA Research Center, Donaueschingenstrasse 13, 1200, Vienna, Austria.|University Clinic of Dentistry, Medical University of Vienna, Sensengasse 2a, 1090, Vienna, Austria.|Austrian Cluster for Tissue Regeneration, Vienna, Austria.
authors.forename: B
authors.initials: B
authors.lastname: Schädl
authors.affiliation: Department of Adhesive Bonding Technology and Surfaces, Fraunhofer Institute for Manufacturing Technology and Advanced Materials, Wiener Strasse 12, 28359 Bremen, Germany.
authors.forename: I
authors.initials: I
authors.lastname: Grunwald
authors.affiliation: Research Centre for Medical Technics and Biotechnology, Geranienweg 7, 99947, Bad Langensalza, Germany.
authors.forename: I
authors.initials: I
authors.lastname: Ponomarev
authors.affiliation: Department of Trauma Surgery, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria.|Austrian Cluster for Tissue Regeneration, Vienna, Austria.
authors.forename: St
authors.initials: S
authors.lastname: Marlovits
authors.affiliation: Clinic and Polyclinic for Traumatology, University of Giessen, Rudolf-Buchheim-Straße 7, 35385, Giessen, Germany.|Orthopaedic and Trauma Surgery, Klinikum Saarbrücken, Winterberg 1, 66119, Saarbrücken, Germany.
authors.forename: Ch
authors.initials: C
authors.lastname: Meyer
authors.affiliation: Research Centre for Medical Technics and Biotechnology, Geranienweg 7, 99947, Bad Langensalza, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Barnewitz
mesh_terms: D000818:Animals; D002358:Cartilage, Articular / Q000166:cytology / Q000648:ultrastructure; D019902:Chondrocytes / Q000166:cytology* / Q000648:ultrastructure; D006736:Horses; D046529:Microscopy, Electron, Transmission; D008928:Mitochondria / Q000737:chemistry* / Q000648:ultrastructure; D013314:Stress, Mechanical
keywords: Cartilage; Chondrocytes; Histochemistry; Mitochondria; Protein crystals; Transmission electron microscopy