Chitosan inhibits fibroblasts growth in Achilles tendon via TGF-β1/Smad3 pathway by miR-29b.

Background And Aim: Chitosan, is a natural polymer, plays an important role in prevention of tendon adhesion in tendon healing process. However, the molecular mechanisms underlying the prevention effect is unclear. Here we investigated the effects of chitosan on Achilles tendon injury rats and fibroblasts.

Methods: Eight weeks after surgery, gliding excursion and the content of collagen fibers in Achilles tendon injury rats were determined to evaluate the chitosan effect on tendon healing. Fibroblasts isolated from scar tissue of repaired tendon were treated with different concentration of chitosan, and then cell inhibition, apoptosis and cell cycle were measured using MTT and Flow Cytometry respectively. The expression of microRNAs (miRNAs) was quantified by real-time PCR and protein expression of TGF-β1, Smad3 and P21 were quantified by western blotting. MiR-29b inhibitor was transfected in cells to evaluate the mechanism underlying the effects of chitosan on tendon fibroblasts.

Results: The gliding excursion of repaired tendon was increased and the content of collagen fibers was decreased by chitosan in rats. Chitosan inhibited the fibroblasts growth and arrested cells in G1 phase. Chitosan also elevated the expression of miR-29b and P21 while reduced the levels of TGFβ1 and Smad3 in both repaired tendon and fibroblasts. In addition, miR-29b inhibitor revered the effects of chitosan on fibroblasts.

Conclusions: The current study demonstrated that chitosan improving the condition of tendon healing after surgery, which is reduced by the high expression of miR-29b and its down-regulation of TGF-β1/Smad3 level and inhibition of fibroblasts growth.