Material properties in unconfined compression of human nucleus pulposus, injectable hyaluronic acid-based hydrogels and tissue engineering scaffolds

Jordan M. Cloyd, Neil R. Malhotra, Lihui Weng, Weiliam Chen, Robert L. Mauck, Dawn M. Elliott

Research output: Contribution to journalArticlepeer-review

176 Scopus citations

Abstract

Surgical treatment for lower back pain related to degenerative disc disease commonly includes discectomy and spinal fusion. While surgical intervention may provide short-term pain relief, it results in altered biomechanics of the spine and may lead to further degenerative changes in adjacent segments. One non-fusion technique currently being investigated is nucleus pulposus (NP) support via either an injectable hydrogel or tissue engineered construct. A major challenge for either approach is to mimic the mechanical properties of native NP. Here we adopt an unconfined compression testing configuration to assess toe-region and linear-region modulus and Poisson's ratio, key functional parameters for NP replacement. Human NP, experimental biocompatible hydrogel formulations composed of hyaluronic acid (HA), PEG-g-chitosan, and gelatin, and conventional alginate and agarose gels were investigated as injectable NP replacements or tissue engineering scaffolds. Testing consisted of a stress-relaxation experiment of 5% strain increments followed by 5-min relaxation periods to a total of 25% strain. Human NP had an average linear-region modulus of 5.39 ± 2.56 kPa and a Poisson's ratio of 0.62 ± 0.15. The modulus and Poisson's ratio are important parameters for evaluating the design of implant materials and scaffolds. The synthetic HA-based hydrogels approximated NP well and may serve as suitable NP implant materials.

Original languageEnglish (US)
Pages (from-to)1892-1898
Number of pages7
JournalEuropean Spine Journal
Volume16
Issue number11
DOIs
StatePublished - Nov 1 2007

Keywords

  • Agarose
  • Alginate
  • Compression
  • Hydrogel
  • Intervertebral disc
  • NP

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