School of Engineering and Materials Science
Research Student Roll of Honours

PhD Thesis: Temporal regulation of tenocyte metabolism in strained fascicles

Author: MAEDA, Eijiro

Year: 2008

Supervisor(s): David Lee, Julia Shelton

The present study tested the global hypothesis that cyclic tensile strain influences catabolism and anabolism of tenocytes, by measuring proline incorporation, expression of selected catabolic and anabolic genes by qPCR, and expression of a comprehensive range of genes by cRNA microarray. Cyclic strain, with a 3% amplitude on a 2% static strain at a frequency of 1 Hz, was applied to fascicles from rat tail tendon for periods between 10 minutes and 24 hours in a custom-made tissue loading system. The application of 10 minutes cyclic strain inhibited proline incorporation into newly synthesised collagen. By contrast, 24 hours continuous cyclic strain upregulated the proline incorporation, which may reflect an upregulation of type III collagen mRNA expression after 6 hours cyclic strain. Catabolic genes MMP3 and MMP13 were both upregulated by 10 minutes cyclic strain, but were subsequently suppressed even with the absence of the continuation of cyclic strain. Microarray analysis revealed that cyclic strain modulates expression of genes involved in the protein synthetic process, upregulating transcription at 1 hour and translation at 24 hours, respectively, and inhibited expression of genes involved in several catabolic processes, such as inflammatory responses and apoptosis. Therefore, results from the present study suggest that tenocyte catabolism and anabolism are differentially regulated by cyclic tensile strain, with the latter requiring an extended stimulation to be activated.