Do cells contribute to tendon and ligament biomechanics?

PLoS One. 2014 Aug 15;9(8):e105037. doi: 10.1371/journal.pone.0105037. eCollection 2014.

Abstract

Introduction: 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.

Material and 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.

Discussion: 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Biomechanical Phenomena
  • Elastic Modulus
  • Female
  • Humans
  • Ligaments / chemistry
  • Ligaments / cytology*
  • Ligaments / physiology*
  • Ligaments / ultrastructure
  • Male
  • Middle Aged
  • Tendons / chemistry
  • Tendons / cytology*
  • Tendons / physiology*
  • Tendons / ultrastructure
  • Tensile Strength
  • Young Adult

Grants and funding

Parts of the work presented in this paper were supported by the German Federal Ministry of Education and Research (BMBF number 1315883, www.bmbf.de). The authors Holger Koch and Andreas Boldt were financed via the German Federal Ministry of Education and Research. In both, they were involved in data collection, analysis and in the preparation of the manuscript. This work was furthermore made possible by the budgetary resources of the Institute of Anatomy, University of Leipzig. The authors declare that there are no competing interests. They acknowledge support from the German Research Foundation (DFG) and Leipzig University within the program of Open Access Publishing. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.