Di-san junyi daxue xuebao (Sep 2019)
Mechanical stretching enhances TGF-β3 and CREB expression to reduce tendon adhesion during tendon healing in rats
Abstract
Objective To evaluate the effect of mechanical stretching in promoting tendon healing and reducing tendon adhesion during the healing of extensor flexor tendon in rats and its effects on the expression of transforming growth factor-β3 (TGF-β3) and cyclic AMP response element-binding protein (CREB). Methods Eighteen male SD rats were randomized into 3 equal groups and subjected to sham operation, flexor tendon injury of the second to fifth digits of the hind limbs without interventions (model group), or flexor tendon injury with daily passive mechanical stretching of the tendon for 1 week after the operation. The tendon was exposed only without injuries in the sham-operated group. At 1, 2, 4, and 8 weeks after the operation, tendon healing of the rats was evaluated by anatomical observation and histological examination, and the expression of TGF-β1, TGF-β3 and CREB in the tendon was detected using real-time fluorescence quantitative PCR and immunohistochemistry. Results Compared with the model group, the rats in mechanical stretching group showed better tendon healing with reduced tendon adhesion, less granular tissue and more regular cell alignment in the tendon (P < 0.05). During tendon healing, the expression of TGF-β3 and CREB mRNAs in the injured tendon were significantly higher at all the time points and the expression of TGF-β1 mRNA at the first week after the operation was significantly lower in mechanical stretching group than in the model group (P < 0.05); TGF-β1 mRNA expression was comparable between the two groups at all the later time points. Immunohistochemical studies showed significantly stronger TGF-β3 and CREB expression in the injured tendons in the mechanical stretching group after the operation, and TGF-β1 expression began to decrease significantly at 1 week after the operation (P < 0.05). Conclusion Mechanical stretching can promote the healing of the flexor tendon and reduce postoperative tendon adhesion in close relation with increased expression of TGF-β3 and CREB and reduced expression of TGF-β1 in the early stage of tendon healing.
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