0
Research Papers

Viscoelastic and Biomechanical Properties of Osteochondral Tissue Constructs Generated From Graded Polycaprolactone and Beta-Tricalcium Phosphate Composites

[+] Author and Article Information
Cevat Erisken1

 Stevens Institute of Technology, Hoboken, NJ 07030ce2213@columbia.edu

Dilhan M. Kalyon2

 Stevens Institute of Technology, Hoboken, NJ 07030dkalyon@stevens.edu

Hongjun Wang

 Stevens Institute of Technology, Hoboken, NJ 07030hongjun.wang@stevens.edu

1

Present address: Department of Biomedical Engineering, Columbia University, New York, NY 10027

2

Corresponding author.

J Biomech Eng 132(9), 091013 (Sep 01, 2010) (9 pages) doi:10.1115/1.4001884 History: Received September 14, 2009; Revised April 29, 2010; Posted May 27, 2010; Published September 01, 2010; Online September 01, 2010

The complex micro-/nanostructure of native cartilage-to-bone insertion exhibits gradations in extracellular matrix components, leading to variations in the viscoelastic and biomechanical properties along its thickness to allow for smooth transition of loads under physiological movements. Engineering a realistic tissue for osteochondral interface would, therefore, depend on the ability to develop scaffolds with properly graded physical and chemical properties to facilitate the mimicry of the complex elegance of native tissue. In this study, polycaprolactone nanofiber scaffolds with spatially controlled concentrations of β-tricalcium phosphate nanoparticles were fabricated using twin-screw extrusion-electrospinning process and seeded with MC3T3-E1 cells to form osteochondral tissue constructs. The objective of the study was to evaluate the linear viscoelastic and compressive properties of the native bovine osteochondral tissue and the tissue constructs formed in terms of their small-amplitude oscillatory shear, unconfined compression, and stress relaxation behavior. The native tissue, engineered tissue constructs, and unseeded scaffolds exhibited linear viscoelastic behavior for strain amplitudes less than 0.1%. Both native tissue and engineered tissue constructs demonstrated qualitatively similar gel-like behavior as determined using linear viscoelastic material functions. The normal stresses in compression determined at 10% strain for the unseeded scaffold, the tissue constructs cultured for four weeks, and the native tissue were 0.87±0.08kPa, 3.59±0.34kPa, and 210.80±8.93kPa, respectively. Viscoelastic and biomechanical properties of the engineered tissue constructs were observed to increase with culture time reflecting the development of a tissuelike structure. These experimental findings suggest that viscoelastic material functions of the tissue constructs can provide valuable inputs for the stages of in vitro tissue development.

FIGURES IN THIS ARTICLE
<>
Copyright © 2010 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

Experimental setup for the viscoelastic and biomechanical characterization of the samples. An environmental chamber held fixtures and specimen immersed in PBS at 37°C.

Grahic Jump Location
Figure 2

Typical distribution of concentration of β-TCP nanoparticles as a function of the distance from the bottom of the scaffold ( ∗ indicates the significance between the groups at p<0.01 level)

Grahic Jump Location
Figure 3

SEM micrographs of the sections of PCL-β-TCP scaffold corresponding to the (a) bottom, (b) middle, and (c) top portions, and their respective EDX mapping ((d)–(f)) and spectrum ((g)–(i))

Grahic Jump Location
Figure 4

(a) Stability analysis of the native tissue in terms of storage and loss moduli in air and in PBS solution at 1 rps, 0.1% strain, and 37°C. Error bars represent the upper and lower bounds of deviations from the mean for 95% confidence interval. (b) Magnitude of complex viscosity versus strain amplitude behavior of unseeded scaffolds (◇), engineered tissue constructs at one week (◻) and four weeks (△), and the native bovine tissue (○), at 1 rps and 37°C. Error bars represent the upper and lower bounds of deviations from the mean for 95% confidence interval.

Grahic Jump Location
Figure 5

(a) Unconfined compression stress-relaxation response of the native tissue (○) and engineered tissue constructs after four weeks (△) over 100 s. (b) Unconfined compression stress-relaxation response of the native tissue over 1000 s and corresponding single relaxation time fit (◆) in the same range. Compression rate is 0.05 mm/s.

Grahic Jump Location
Figure 6

Frequency dependence of (a) the storage modulus, (b) the loss modulus, and (c) the tan delta of the native tissue (○), tissue constructs after four weeks (△) and one week (◻), and the unseeded scaffolds (◇) at 0.1% strain and 37°C. The best fit of the generalized Maxwell model for the native tissue (–), tissue constructs after four weeks (---) and one week (–⋅–⋅), and the unseeded scaffolds (– –) are also provided. Error bars represent the upper and lower bounds of the deviations from the mean for 95% confidence interval (n=3).

Grahic Jump Location
Figure 7

Stress-strain behavior of native tissue (○), engineered tissue constructs after four weeks (△), and the unseeded scaffolds (◇). Compression rate is 0.05 mm/min. Error bars represent the upper and lower bounds of deviations from the mean for 95% confidence interval.

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In