Experimental study of inhibition of tendon fibroblast growth by chitosan through the pathway of TGF-β1/Smad3 mediated by miR-29b

Abstract

Objective To study the molecular mechanism of chitosan inhibiting fibroblast growth after tendon repair. Methods The rats with Achilles tendon injury were treated with chitosan during operation, and the sliding distance and total collagen content were examined 8 weeks postoperatively. Simultaneously, the fibroblasts in the repaired tendon tissue were separated and treated with different concentrations of chitosan. The survival rate, apoptosis and cell cycle of the cells were examined. In addition, the expression of miRNAs was quantified by real-time PCR and expression of TGF-β1, Smad3 and P21were quantified by western blot. Results Chitosan can increase the tendon gliding distance, reduce the content of collagen fibers, inhibit the growth of fibroblasts and arrest cells in G1 phase of the growth cycle. Chitosan also up-regulated the expression of miR-29b and P21 but down-regulated the levels of TGF-β1and Smad3 in repaired tendon tissue and in vitro fibroblasts. In fibroblasts, miR-29b inhibitor can reverse the expression changes of miR-29b、TGF-β1、Smad3 and P21 induced by chitosan. Conclusion Chitosan can promote the repair of Achilles tendon injury in rats. miR-29b causes fibroblasts staying at G1 phase by down-regulating the expression of TGF-β1and Smad3 and up-regulating the expression of P21. It may be one of the mechanisms of chitosan playing a positive role in the process of tendon repair. Key words: Tendon injuries; Chitosan; Fibroblasts; miR-29b