title: Loss of spatial organization and destruction of the pericellular matrix in early osteoarthritis in vivo and in a novel in vitro methodology.
abstract: Current repair procedures for articular cartilage (AC) cannot restore the tissue's original form and function because neither changes in its architectural blueprint throughout life nor the respective biological understanding is fully available. We asked whether two unique elements of human cartilage architecture, the chondrocyte-surrounding pericellular matrix (PCM) and the superficial chondrocyte spatial organization (SCSO) beneath the articular surface (AS) are congenital, stable or dynamic throughout life. We hypothesized that inducing chondrocyte proliferation in vitro impairs organization and PCM and induces an advanced osteoarthritis (OA)-like structural phenotype of human cartilage.
  
  
  
  We recorded propidium-iodine-stained fetal and adult cartilage explants, arranged stages of organization into a sequence, and created a lifetime-summarizing SCSO model. To replicate the OA-associated dynamics revealed by our model, and to test our hypothesis, we transduced specifically early OA-explants with hFGF-2 for inducing proliferation. The PCM was examined using immuno- and auto-fluorescence, multiphoton second-harmonic-generation (SHG), and scanning electron microscopy (SEM).
  
  
  
  Spatial organization evolved from fetal homogeneity, peaked with adult string-like arrangements, but was completely lost in OA. Loss of organization included PCM perforation (local micro-fibrillar collagen intensity decrease) and destruction [regional collagen type VI (CollVI) signal weakness or absence]. Importantly, both loss of organization and PCM destruction were successfully recapitulated in FGF-2-transduced explants.
  
  
  
  Induced proliferation of spatially characterized early OA-chondrocytes within standardized explants recapitulated the full range of loss of SCSO and PCM destruction, introducing a novel in vitro methodology. This methodology induces a structural phenotype of human cartilage that is similar to advanced OA and potentially of significance and utility.
authors.affiliation: Siegfried Weller Institute for Trauma Research, BG Trauma Clinic Tuebingen, University of Tuebingen, Tuebingen, Germany. Electronic address: tino579@yahoo.de.
authors.forename: T
authors.initials: T
authors.lastname: Felka
authors.affiliation: Siegfried Weller Institute for Trauma Research, BG Trauma Clinic Tuebingen, University of Tuebingen, Tuebingen, Germany. Electronic address: miriam.rothdiener@uni-tuebingen.de.
authors.forename: M
authors.initials: M
authors.lastname: Rothdiener
authors.affiliation: Siegfried Weller Institute for Trauma Research, BG Trauma Clinic Tuebingen, University of Tuebingen, Tuebingen, Germany. Electronic address: sina.bast@gmx.net.
authors.forename: S
authors.initials: S
authors.lastname: Bast
authors.affiliation: Siegfried Weller Institute for Trauma Research, BG Trauma Clinic Tuebingen, University of Tuebingen, Tuebingen, Germany. Electronic address: tanya_u@web.de.
authors.forename: T
authors.initials: T
authors.lastname: Uynuk-Ool
authors.affiliation: Department of Cardiac, Thoracic and Vascular Sciences, University of Padua, Padua, Italy. Electronic address: sabra.zouhair@gmail.com.
authors.forename: S
authors.initials: S
authors.lastname: Zouhair
authors.affiliation: Clinic for Trauma and Restorative Surgery, BG Trauma Clinic Tuebingen, University of Tuebingen, Tuebingen, Germany. Electronic address: gochs@bgu-tuebingen.de.
authors.forename: B G
authors.initials: BG
authors.lastname: Ochs
authors.affiliation: Clinic for Trauma and Restorative Surgery, BG Trauma Clinic Tuebingen, University of Tuebingen, Tuebingen, Germany. Electronic address: PdeZwart@bgu-tuebingen.de.
authors.forename: P
authors.initials: P
authors.lastname: De Zwart
authors.affiliation: Clinic for Trauma and Restorative Surgery, BG Trauma Clinic Tuebingen, University of Tuebingen, Tuebingen, Germany. Electronic address: ustoeckle@bgu-tuebingen.de.
authors.forename: U
authors.initials: U
authors.lastname: Stoeckle
authors.affiliation: Department of Urology, University of Tuebingen, Tuebingen, Germany. Electronic address: aicher@uni-tuebingen.de.
authors.forename: W K
authors.initials: WK
authors.lastname: Aicher
authors.affiliation: Department of Urology, University of Tuebingen, Tuebingen, Germany. Electronic address: melaniehar@gmail.com.
authors.forename: M L
authors.initials: ML
authors.lastname: Hart
authors.affiliation: Institute of Clinical Anatomy and Cell Analysis, University of Tuebingen, Tuebingen, Germany. Electronic address: thomas.shiozawa@uni-tuebingen.de.
authors.forename: T
authors.initials: T
authors.lastname: Shiozawa
authors.affiliation: Center for Biomedical Engineering, Massachusetts Institute of Technology, Cambridge, USA. Electronic address: alg@mit.edu.
authors.forename: A J
authors.initials: AJ
authors.lastname: Grodzinsky
authors.affiliation: Department of Women's Health, Research Institute for Women's Health, University of Tuebingen, Tuebingen, Germany; Department of Cell and Tissue Engineering, Fraunhofer Institute for Interfacial Engineering and Biotechnology (IGB), Stuttgart, Germany. Electronic address: katja.schenke-layland@igb.fraunhofer.de.
authors.forename: K
authors.initials: K
authors.lastname: Schenke-Layland
authors.affiliation: Center of Experimental Orthopaedics, Saarland University Medical Center, Homburg, Germany. Electronic address: jegadish.venki@gmail.com.
authors.forename: J K
authors.initials: JK
authors.lastname: Venkatesan
authors.affiliation: Center of Experimental Orthopaedics, Saarland University Medical Center, Homburg, Germany. Electronic address: mmcucchiarini@hotmail.com.
authors.forename: M
authors.initials: M
authors.lastname: Cucchiarini
authors.affiliation: Center of Experimental Orthopaedics, Saarland University Medical Center, Homburg, Germany. Electronic address: Henning.Madry@uniklinikum-saarland.de.
authors.forename: H
authors.initials: H
authors.lastname: Madry
authors.affiliation: Anatomical Institute, Christian-Albrecht-University Kiel, Kiel, Germany. Electronic address: bkurz@anat.uni-kiel.de.
authors.forename: B
authors.initials: B
authors.lastname: Kurz
authors.affiliation: Siegfried Weller Institute for Trauma Research, BG Trauma Clinic Tuebingen, University of Tuebingen, Tuebingen, Germany; Clinic for Trauma and Restorative Surgery, BG Trauma Clinic Tuebingen, University of Tuebingen, Tuebingen, Germany; Center for Biomedical Engineering, Massachusetts Institute of Technology, Cambridge, USA. Electronic address: berndrolauffs@googlemail.com.
authors.forename: B
authors.initials: B
authors.lastname: Rolauffs
mesh_terms: D002358:Cartilage, Articular; D019902:Chondrocytes; D005109:Extracellular Matrix; D016222:Fibroblast Growth Factor 2; D006801:Humans; D010003:Osteoarthritis
chemical_list: D016222:Fibroblast Growth Factor 2
keywords: Articular cartilage; Cellular distribution; Chondrocyte; Early osteoarthritis; Pericellular matrix; Superficial zone