title: Supramolecular Organization of Collagen Fibrils in Healthy and Osteoarthritic Human Knee and Hip Joint Cartilage.
abstract: Cartilage matrix is a composite of discrete, but interacting suprastructures, i.e. cartilage fibers with microfibrillar or network-like aggregates and penetrating extrafibrillar proteoglycan matrix. The biomechanical function of the proteoglycan matrix and the collagen fibers are to absorb compressive and tensional loads, respectively. Here, we are focusing on the suprastructural organization of collagen fibrils and the degradation process of their hierarchical organized fiber architecture studied at high resolution at the authentic location within cartilage. We present electron micrographs of the collagenous cores of such fibers obtained by an improved protocol for scanning electron microscopy (SEM). Articular cartilages are permeated by small prototypic fibrils with a homogeneous diameter of 18 ± 5 nm that can align in their D-periodic pattern and merge into larger fibers by lateral association. Interestingly, these fibers have tissue-specific organizations in cartilage. They are twisted ropes in superficial regions of knee joints or assemble into parallel aligned cable-like structures in deeper regions of knee joint- or throughout hip joints articular cartilage. These novel observations contribute to an improved understanding of collagen fiber biogenesis, function, and homeostasis in hyaline cartilage.
authors: Department of Biophysical and Electronic Engineering, University of Genova, Genova, Italy.|Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, United States of America.|Ri.MED Foundation, Palermo, Italy.
authors: Riccardo
authors: R
authors: Gottardi
authors: Institute of Experimental Musculoskeletal Medicine, University Hospital of Münster, Münster, Germany.|Institute for Physiological Chemistry and Pathochemistry, University of Münster, Münster, Germany.
authors: Uwe
authors: U
authors: Hansen
authors: Department of Biophysical and Electronic Engineering, University of Genova, Genova, Italy.
authors: Roberto
authors: R
authors: Raiteri
authors: Biozentrum University of Basel, Basel, Switzerland.
authors: Marko
authors: M
authors: Loparic
authors: Center for Microscopy, University of Basel, Basel, Switzerland.
authors: Marcel
authors: M
authors: Düggelin
authors: Center for Microscopy, University of Basel, Basel, Switzerland.
authors: Daniel
authors: D
authors: Mathys
authors: Department of Orthopaedic Surgery & Traumatology, Kantonsspital Bruderholz/Basel, Basel, Switzerland.
authors: Niklaus F
authors: NF
authors: Friederich
authors: Institute for Physiological Chemistry and Pathochemistry, University of Münster, Münster, Germany.
authors: Peter
authors: P
authors: Bruckner
authors: Biozentrum University of Basel, Basel, Switzerland.|nCATS (national Centre for Advanced Tribology at Southampton), Engineering and the Environment, University of Southampton, Southampton, United Kingdom.
authors: Martin
authors: http://orcid.org/0000-0002-0732-0811
authors: M
authors: Stolz
mesh_terms: D002358:Cartilage, Articular / Q000473:pathology / Q000648:ultrastructure*; D024022:Fibrillar Collagens / Q000737:chemistry*; D006621:Hip Joint / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007719:Knee Joint / Q000378:metabolism / Q000473:pathology; D008855:Microscopy, Electron, Scanning; D015207:Osteoarthritis, Hip / Q000378:metabolism / Q000473:pathology*; D020370:Osteoarthritis, Knee / Q000378:metabolism / Q000473:pathology*
chemical_list: D024022:Fibrillar Collagens