Date of Award

11-3-2006

Document Type

Open Access Thesis

Degree Name

Medical Doctor (MD)

First Advisor

J Grant Thomson

Abstract

The purpose of this study was to examine the effects of cyclic tension on the expression of hyaluronic acid, its receptor (CD44), and total glycosaminoglycan content in tendon fibroblasts. An in vitro model was used to analyze tenocytes from the tail tendons of rats. Tenocytes in the experimental group were exposed to cyclic mechanical stress, and using ELISA, western blot, and colormetric dye-binding assays, the effect of strain on cultured tenocytes was examined. Tenocytes exposed to mechanical strain produced 1528 ± 58 ng/mL (mean ± SEM) of hyaluronic acid, while those in a control environment produced only 730 ± 27 ng/mL; nearly a two-fold difference (p<.0001, n=44). CD44, the receptor for hyaluronic acid, was also detected in higher concentrations. Tenocytes under mechanical strain increased their concentration of CD44 by 62.5%, with tenocytes exposed to strain having an optical density of 26 . 103 ± 2 . 103 compared with 15 . 103 ± 1 . 103 in controls (p<.05, n=6). The total glycosaminoglycan content of the two groups did not differ significantly; strained cells produced 10.2 ± 0.6 µg/mL and controls producing 15.3 ± 3 µg/mL (p=0.103, n=44). We conclude that mechanical strain in tendon fibroblasts is sufficient to induce the production of hyaluronic acid and increase the expression of its receptor, CD44. The results of our study suggest that the beneficial effects on tendon adhesion formation seen with both mechanical strain and hyaluronic acid may be related in their mechanism.

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