title: Do cells contribute to tendon and ligament biomechanics?
abstract: BACKGROUND
  Acellular scaffolds are increasingly used for the surgical repair of tendon injury and ligament tears. Despite this increased use, very little data exist directly comparing acellular scaffolds and their native counterparts. Such a comparison would help establish the effectiveness of the acellularization procedure of human tissues. Furthermore, such a comparison would help estimate the influence of cells in ligament and tendon stability and give insight into the effects of acellularization on collagen.
  
  
  METHODS
  Eighteen human iliotibial tract samples were obtained from nine body donors. Nine samples were acellularized with sodium dodecyl sulphate (SDS), while nine counterparts from the same donors remained in the native condition. The ends of all samples were plastinated to minimize material slippage. Their water content was adjusted to 69%, using the osmotic stress technique to exclude water content-related alterations of the mechanical properties. Uniaxial tensile testing was performed to obtain the elastic modulus, ultimate stress and maximum strain. The effectiveness of the acellularization procedure was histologically verified by means of a DNA assay.
  
  
  RESULTS
  The histology samples showed a complete removal of the cells, an extensive, yet incomplete removal of the DNA content and alterations to the extracellular collagen. Tensile properties of the tract samples such as elastic modulus and ultimate stress were unaffected by acellularization with the exception of maximum strain.
  
  
  CONCLUSIONS
  The data indicate that cells influence the mechanical properties of ligaments and tendons in vitro to a negligible extent. Moreover, acellularization with SDS alters material properties to a minor extent, indicating that this method provides a biomechanical match in ligament and tendon reconstruction. However, the given protocol insufficiently removes DNA. This may increase the potential for transplant rejection when acellular tract scaffolds are used in soft tissue repair. Further research will help optimize the SDS-protocol for clinical application.
authors.affiliation: Institute of Anatomy, University of Leipzig, Faculty of Medicine, Leipzig, Germany.
authors.forename: Niels
authors.initials: N
authors.lastname: Hammer
authors.affiliation: Institute of Medical Physics and Biophysics, University of Leipzig, Faculty of Medicine, Leipzig, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Huster
authors.affiliation: Institute of Materials Science and Engineering, Chemnitz University of Technology, Chemnitz, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Fritsch
authors.affiliation: Institute of Forensic Medicine, University of Leipzig, Faculty of Medicine, Leipzig, Germany.
authors.forename: Carsten
authors.initials: C
authors.lastname: Hädrich
authors.affiliation: Translational Centre for Regenerative Medicine, University of Leipzig, Faculty of Medicine, Leipzig, Germany.
authors.forename: Holger
authors.initials: H
authors.lastname: Koch
authors.affiliation: Institute of Medical Physics and Biophysics, University of Leipzig, Faculty of Medicine, Leipzig, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Schmidt
authors.affiliation: Institute of Sport Science, Department Human Locomotion, Chemnitz University of Technology, Chemnitz, Germany.
authors.forename: Freddy
authors.initials: F
authors.lastname: Sichting
authors.affiliation: Institute of Materials Science and Engineering, Chemnitz University of Technology, Chemnitz, Germany.
authors.forename: Martin Franz-Xaver
authors.initials: MF
authors.lastname: Wagner
authors.affiliation: Translational Centre for Regenerative Medicine, University of Leipzig, Faculty of Medicine, Leipzig, Germany; Institute of Clinical Immunology, University of Leipzig, Faculty of Medicine, Leipzig, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Boldt
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D055119:Elastic Modulus; D005260:Female; D006801:Humans; D008022:Ligaments / Q000737:chemistry / Q000166:cytology* / Q000502:physiology* / Q000648:ultrastructure; D008297:Male; D008875:Middle Aged; D013710:Tendons / Q000737:chemistry / Q000166:cytology* / Q000502:physiology* / Q000648:ultrastructure; D013718:Tensile Strength; D055815:Young Adult