Annals of Biomedical Engineering

, Volume 42, Issue 3, pp 619–630

The Tendon Injury Response is Influenced by Decorin and Biglycan

Authors

  • Andrew A. Dunkman
    • The McKay Orthopaedic Research LaboratoryUniversity of Pennsylvania
  • Mark R. Buckley
    • The McKay Orthopaedic Research LaboratoryUniversity of Pennsylvania
  • Michael J. Mienaltowski
    • Department of Molecular Pharmacology & Physiology, Morsani College of MedicineUniversity of South Florida
  • Sheila M. Adams
    • Department of Molecular Pharmacology & Physiology, Morsani College of MedicineUniversity of South Florida
  • Stephen J. Thomas
    • The McKay Orthopaedic Research LaboratoryUniversity of Pennsylvania
  • Lauren Satchell
    • The McKay Orthopaedic Research LaboratoryUniversity of Pennsylvania
  • Akash Kumar
    • The McKay Orthopaedic Research LaboratoryUniversity of Pennsylvania
  • Lydia Pathmanathan
    • The McKay Orthopaedic Research LaboratoryUniversity of Pennsylvania
  • David P. Beason
    • The McKay Orthopaedic Research LaboratoryUniversity of Pennsylvania
  • Renato V. Iozzo
    • Department of Pathology, Anatomy & Cell BiologyThomas Jefferson University
  • David E. Birk
    • Department of Molecular Pharmacology & Physiology, Morsani College of MedicineUniversity of South Florida
    • The McKay Orthopaedic Research LaboratoryUniversity of Pennsylvania
Article

DOI: 10.1007/s10439-013-0915-2

Cite this article as:
Dunkman, A.A., Buckley, M.R., Mienaltowski, M.J. et al. Ann Biomed Eng (2014) 42: 619. doi:10.1007/s10439-013-0915-2

Abstract

Defining the constituent regulatory molecules in tendon is critical to understanding the process of tendon repair and instructive to the development of novel treatment modalities. The purpose of this study is to define the structural, expressional, and mechanical changes in the tendon injury response, and elucidate the roles of two class I small leucine-rich proteoglycans (SLRPs). We utilized biglycan-null, decorin-null and wild type mice with an established patellar tendon injury model. Mechanical testing demonstrated functional changes associated with injury and the incomplete recapitulation of mechanical properties after 6 weeks. In addition, SLRP deficiency influenced the mechanical properties with a marked lack of improvement between 3 and 6 weeks in decorin-null tendons. Morphological analyses of the injury response and role of SLRPs demonstrated alterations in cell density and shape as well as collagen alignment and fibril structure resulting from injury. SLRP gene expression was studied using RT-qPCR with alterations in expression associated with the injured tendons. Our results show that in the absence of biglycan initial healing may be impaired while in the absence of decorin later healing is clearly diminished. This suggests that biglycan and decorin may have sequential roles in the tendon response to injury.

Keywords

TendonInjuryBiglycanDecorinProteoglycanExtracellular matrixSLRPHealing

Supplementary material

10439_2013_915_MOESM1_ESM.pdf (256 kb)
Supplementary material 1 (PDF 256 kb) S-Table 1. RT-qPCR: Mean Ct numbers and mean plate efficiencies, raw data
10439_2013_915_MOESM2_ESM.lnk (1 kb)
Supplementary material 2 (LNK 0 kb) S-Fig. 1. Mean dynamic modulus and mean tanδ for each genotype at each tested strain and frequency. Note the increasing spread between 3 weeks and 6 weeks in WT and Bgn−/− (but not Dcn/) as strain increases. Seemingly, remodeling is more influential at these higher strains. See Figs. 1 and 2 for representative error bars; Table 1 and Table 2 for statistics
10439_2013_915_MOESM3_ESM.lnk (1 kb)
Supplementary material 3 (LNK 0 kb) S-Fig. 2. Quasi-static properties from ramp to failure and p-values from t tests. (a) toe modulus. (b) linear modulus. (c) transition strain (d) transition stress
10439_2013_915_MOESM4_ESM.lnk (1 kb)
Supplementary material 4 (LNK 0 kb) S-Fig. 3. A prepared tendon undergoing mechanical testing

Copyright information

© Biomedical Engineering Society 2013