Name: Gregory M. Williams
Email: gmwillia @ ucsd.edu
Grad Year: 2008
Jessica W. Lin, j4lin @ ucsd.edu
Cartilage Reshaping Via In Vitro Mechanical Loading Gregory M. Williams1, Jessica W. Lin1, Robert L. Sah1,2 1Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA 2Whitaker Institute of Biomedical Engineering, University of California, San Diego, La Jolla, CA 92093, USA
Mechanical forces can regulate the growth of articular cartilage and influence the morphology of the developing joint. The ability to shape cartilage into anatomical geometries may prove useful in the treatment of cartilage injury and disease. This study's hypothesis is that the application of bending loads to immature cartilage in culture will facilitate tissue reshaping through the metabolic processes of chondrocytes and cartilage matrix. Immature articular cartilage strips were either placed in custom-built loading devices or left free-swelling as a control, and cultured in DMEM + 20% FBS for 2, 4, and 6 days. Following culture, changes in specimen shape and the percent retention of the imposed shape were calculated. Further manipulations were used to examine whether cell and matrix metabolism mediate the reshaping process. The loading devices imposed a bending deformation on the samples, measured as a ~90° change in opening angle. Following relaxation, loaded samples showed markedly changed shapes compared to the samples in free-swelling culture. Shape retention for the loaded samples was ~65% after 2 days in culture and >80% after 4 and 6 days. Culture with cycloheximide had little effect on the tissue reshaping, but culture at 4°C with cycloheximide markedly restricted the reshaping process. These results demonstrate that mechanical stimuli in vitro can modulate the shape of growing cartilage. While cell metabolism may play a small role in this process, cartilage matrix metabolism or a temperature-dependent mechanical phenomenon may be a primary mechanism. The ability to modulate immature cartilage shape in vitro may facilitate the understanding of cartilage growth in vivo and also be useful for tissue engineering applications.
This work was supported by NIH, NSF, HHMI, an NSF Graduate Research Fellowship (GMW), and UC LEADS (JWL).
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