Mechanical characterization of human brain tumors from patients and comparison to potential surgical phantoms

PLoS One. 2017 Jun 5;12(6):e0177561. doi: 10.1371/journal.pone.0177561. eCollection 2017.

Abstract

While mechanical properties of the brain have been investigated thoroughly, the mechanical properties of human brain tumors rarely have been directly quantified due to the complexities of acquiring human tissue. Quantifying the mechanical properties of brain tumors is a necessary prerequisite, though, to identify appropriate materials for surgical tool testing and to define target parameters for cell biology and tissue engineering applications. Since characterization methods vary widely for soft biological and synthetic materials, here, we have developed a characterization method compatible with abnormally shaped human brain tumors, mouse tumors, animal tissue and common hydrogels, which enables direct comparison among samples. Samples were tested using a custom-built millimeter-scale indenter, and resulting force-displacement data is analyzed to quantify the steady-state modulus of each sample. We have directly quantified the quasi-static mechanical properties of human brain tumors with effective moduli ranging from 0.17-16.06 kPa for various pathologies. Of the readily available and inexpensive animal tissues tested, chicken liver (steady-state modulus 0.44 ± 0.13 kPa) has similar mechanical properties to normal human brain tissue while chicken crassus gizzard muscle (steady-state modulus 3.00 ± 0.65 kPa) has similar mechanical properties to human brain tumors. Other materials frequently used to mimic brain tissue in mechanical tests, like ballistic gel and chicken breast, were found to be significantly stiffer than both normal and diseased brain tissue. We have directly compared quasi-static properties of brain tissue, brain tumors, and common mechanical surrogates, though additional tests would be required to determine more complex constitutive models.

Publication types

  • Comparative Study

MeSH terms

  • Animals
  • Biomechanical Phenomena
  • Biomimetic Materials / chemistry*
  • Brain / anatomy & histology
  • Brain / pathology
  • Brain Chemistry*
  • Brain Neoplasms / chemistry*
  • Brain Neoplasms / pathology
  • Chickens
  • Elastic Modulus
  • Gizzard, Avian / chemistry
  • Humans
  • Hydrogels
  • Liver / chemistry*
  • Materials Testing
  • Mice
  • Muscle, Smooth / chemistry*
  • Tissue Engineering

Substances

  • Hydrogels

Grants and funding

The work was partially supported by Investigator-Initiated Grant #AGR DTD 07-28-2015 to CSS from Medtronic, Inc. There was no additional external funding received for this study. Internal funding was provided from the Department of Mechanical and Aerospace Engineering and the Herbert Wertheim College of Engineering at the University of Florida. Publication of this article was funded in part by the University of Florida Open Access Publishing Fund. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.