title: Acellularization-Induced Changes in Tensile Properties Are Organ Specific - An In-Vitro Mechanical and Structural Analysis of Porcine Soft Tissues.
abstract: BACKGROUND
  Though xenogeneic acellular scaffolds are frequently used for surgical reconstruction, knowledge of their mechanical properties is lacking. This study compared the mechanical, histological and ultrastructural properties of various native and acellular specimens.
  
  
  METHODS
  Porcine esophagi, ureters and skin were tested mechanically in a native or acellular condition, focusing on the elastic modulus, ultimate tensile stress and maximum strain. The testing protocol for soft tissues was standardized, including the adaption of the tissue's water content and partial plastination to minimize material slippage as well as templates for normed sample dimensions and precise cross-section measurements. The native and acellular tissues were compared at the microscopic and ultrastructural level with a focus on type I collagens.
  
  
  RESULTS
  Increased elastic modulus and ultimate tensile stress values were quantified in acellular esophagi and ureters compared to the native condition. In contrast, these values were strongly decreased in the skin after acellularization. Acellularization-related decreases in maximum strain were found in all tissues. Type I collagens were well-preserved in these samples; however, clotting and a loss of cross-linking type I collagens was observed ultrastructurally. Elastins and fibronectins were preserved in the esophagi and ureters. A loss of the epidermal layer and decreased fibronectin content was present in the skin.
  
  
  CONCLUSIONS
  Acellularization induces changes in the tensile properties of soft tissues. Some of these changes appear to be organ specific. Loss of cross-linking type I collagen may indicate increased mechanical strength due to decreasing transverse forces acting upon the scaffolds, whereas fibronectin loss may be related to decreased load-bearing capacity. Potentially, the alterations in tissue mechanics are linked to organ function and to the interplay of cells and the extracellular matrix, which is different in hollow organs when compared to skin.
authors.affiliation: Department of Orthopedic, Trauma and Plastic Surgery, University of Leipzig, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Schleifenbaum
authors.affiliation: Department of Orthopedic, Trauma and Plastic Surgery, University of Leipzig, Germany.
authors.forename: Torsten
authors.initials: T
authors.lastname: Prietzel
authors.affiliation: Department of Surgery, Research Laboratories, University of Leipzig, Germany.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Aust
authors.affiliation: Institute of Clinical Immunology, University of Leipzig, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Boldt
authors.affiliation: Institute of Materials Science and Engineering, Technische Universität Chemnitz, Chemnitz, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Fritsch
authors.affiliation: Institute of Materials Science and Engineering, Technische Universität Chemnitz, Chemnitz, Germany.|Institute of Anatomy, University of Leipzig, Leipzig, Germany.
authors.forename: Isabel
authors.initials: I
authors.lastname: Keil
authors.affiliation: Translational Centre for Regenerative Medicine (TRM), Leipzig, Germany.
authors.forename: Holger
authors.initials: H
authors.lastname: Koch
authors.affiliation: Institute of Anatomy, University of Leipzig, Leipzig, Germany.
authors.forename: Robert
authors.initials: R
authors.lastname: Möbius
authors.affiliation: Institute for Medical Physics and Biophysics, University of Leipzig, Leipzig, Germany.
authors.forename: Holger A
authors.initials: HA
authors.lastname: Scheidt
authors.affiliation: Institute of Materials Science and Engineering, Technische Universität Chemnitz, Chemnitz, Germany.
authors.forename: Martin F X
authors.initials: MF
authors.lastname: Wagner
authors.affiliation: Department of Anatomy, University of Otago, Dunedin, New Zealand.
authors.forename: Niels
authors.initials: N
authors.lastname: Hammer
mesh_terms: D000818:Animals; D024042:Collagen Type I / Q000378:metabolism; D055119:Elastic Modulus / Q000502:physiology; D005109:Extracellular Matrix / Q000378:metabolism; D013552:Swine; D013718:Tensile Strength / Q000502:physiology*
chemical_list: D024042:Collagen Type I