Investigations of Strain Fields in 3D Hydrogels Under Dynamic Confined Loading
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Hydrogels are common scaffolds used to maintain chondrocyte phenotype in culture for mechanobiology and tissue engineering studies. However, the internal strain field and the zone-specific deformation patterns of chondrocytes within hydrogels under dynamic compressive strain have not been well characterized. In this study, we characterized the strain fields within the surface, middle and bottom zones of 3-dimensional collagen and agarose hydrogel constructs, in response to 5 and 15% applied compressive strain. Hydrogel microstructure and chondrocyte deformation were also analysed and compared to uncompressed conditions using scanning electron microscopy. We observed that there are inhomogeneous strain distributions in both collagen and agarose hydrogel constructs. In collagen gels, we observed that the microstructure varied greatly between uncompressed gels to gels with 5% applied compression. The percentage porosity in the surface zone of the gel decreased significantly upon initial application of 5% compression, but remained unchanged when compressed further to 15%. In agarose gels, only the cells in the middle zone of the gel deformed significantly under compression while cells in the other zones underwent deformation that was not statistically significant. These findings indicate that deformation of chondrocytes seeded hydrogels under compression is both inhomogeneous and location-dependent. Therefore, it is important to consider these inhomogeneities in order to accurately understand how mechanical stimuli may affect chondrocyte behaviour.
KeywordsCollagen gel Agarose gel Inhomogeneities Strain distribution Tissue engineering Articular cartilage
This work has been supported by the Health Research Council of New Zealand Grant (ERFG 11/496). The authors would also like to thank Jung Joo Kim for his contribution to this work.
- 5.Neidlinger-Wilke, C., Wurtz, K., Liedert, A., Schmidt, C., Borm, W., Ignatius, A., et al. (2005). A three-dimensional collagen matrix as a suitable culture system for the comparison of cyclic strain and hydrostatic pressure effects on intervertebral disc cells. J Neurosurg Spine., 2, 457–465. doi: 10.3171/spi.2005.2.4.0457.CrossRefGoogle Scholar
- 10.Shim, V., Besier, T., Lloyd, D., Mithraratne, K., & Fernandez, J. (2016). The influence and biomechanical role of cartilage split line pattern on tibiofemoral cartilage stress distribution during the stance phase of gait. Biomechanics and Modeling in Mechanobiology, 15, 195–204. doi: 10.1007/s10237-015-0668-y.
- 12.Hasler, E. M., Herzog, W., Wu, J. Z., Müller, W., & Wyss, U. (1999). Articular cartilage biomechanics: Theoretical models, material properties, and biosynthetic response. Critical Reviews in Biomedical Engineering, 27, 415–488.Google Scholar
- 15.Hoffman, A. S. (2001). Hydrogels for biomedical applications. Annals of the New York Academy of Sciences, 944, 62–73. http://www.ncbi.nlm.nih.gov/pubmed/11797696.
- 18.van Beuningen, H. M., Stoop, R., Buma, P., Takahashi, N., van der Kraan, P. M., & van den Berg, W. B. (2002). Phenotypic differences in murine chondrocyte cell lines derived from mature articular cartilage. Osteoarthritis and Cartilage, 10, 977–986. doi: 10.1053/joca.2002.0855.CrossRefGoogle Scholar
- 23.Knight, M. M., Van de Breevaart Bravenboer, J., Lee, D. A., van Osch, G., Weinans, H., & Bader, D. L. (2002). Cell and nucleus deformation in compressed chondrocyte–alginate constructs: Temporal changes and calculation of cell modulus. Biochimica et Biophysica Acta (BBA)-General Subjects, 1570, 1–8.CrossRefGoogle Scholar
- 26.Martin, I., Obradovic, B., Treppo, S., Grodzinsky, A. J., Langer, R., Freed, L. E., et al. (2000). Modulation of the mechanical properties of tissue engineered cartilage. Biorheology, 37, 141–147.Google Scholar
- 29.Hughes, L. C., Archer, C. W. & Ap Gwynn, I. (2005). The ultrastructure of mouse articular cartilage: Collagen orientation and implications for tissue functionality. A polarised light and scanning electron microscope study and review. European Cells & Materials, 9, 68–84. http://www.ncbi.nlm.nih.gov/pubmed/15968593.
- 34.Ng, K. W., Wang, C. C.-B., Mauck, R. L., Kelly, T.-A. N., Chahine, N. O., Costa, K. D., et al. (2005). A layered agarose approach to fabricate depth-dependent inhomogeneity in chondrocyte-seeded constructs. Journal of Orthopaedic Research, 23, 134–141. doi: 10.1016/j.orthres.2004.05.015.CrossRefGoogle Scholar
- 35.Wang, C. C.-B., Deng, J.-M., Ateshian, G. A., & Hung, C. T. (2002). An automated approach for direct measurement of two-dimensional strain distributions within articular cartilage under unconfined compression. Journal of Biomechanical Engineering, 124, 557–567. doi: 10.1115/1.1503795.CrossRefGoogle Scholar
- 38.Augenstein, K. F., Cowan, B. R., LeGrice, I. J., Nielsen, P. M. F., & Young, A. A. (2005). Method and apparatus for soft tissue material parameter estimation using tissue tagged magnetic resonance imaging. Journal of Biomechanical Engineering, 127, 148–157. doi: 10.1115/1.1835360.CrossRefGoogle Scholar
- 39.Parker, M. D., Azhar, M., Babarenda Gamage, T. P., Alvares, D., Taberner, A. J., & Nielsen, P. M. F. (2012). Surface deformation tracking of a silicone gel skin phantom in response to normal indentation. Engineering in Medicine and Biology Society (EMBC), 2012 Annual International Conference of the IEEE. doi: 10.1109/EMBC.2012.6345984.Google Scholar
- 40.Kim, J. J. (2015). The development of cell gym and its applications to tissue engineering. Auckland: University of Auckland.Google Scholar