Reduction of Tendon Fibrosis Using Galectin-3 Inhibitors.

BACKGROUND: Fibrosis is a complication of both tendon injuries and repairs. We aim to develop a mouse model to assess tendon fibrosis and to identify an antifibrotic agent capable of overcoming tendon fibrosis. METHODS: Adult C57Bl/6 mice underwent a skin incision to expose the Achilles tendon, followed by 50% tendon injury and abrasion with sandpaper. Sham surgeries were conducted on contralateral hindlimbs. Histology and immunofluorescent staining for fibrotic markers (Col1, α-SMA) were used to confirm that the model induced tendon fibrosis. A second experiment was conducted to further examine the role of α-SMA in adhesion formation using α-SMA.mTmG mice (6-8 weeks old) (n=3) with the same injury model. The control group (tendon injury) was compared to the sham group, using the contralateral limb with skin incision only. A second experiment was conducted to further examine the role of α-SMA in adhesion formation using α-SMA.mTmG mice (6-8 weeks old) (n=3) with the same injury model. The control group (tendon injury) was compared to the sham group, using the contralateral limb with skin incision only. Lastly, α-SMA.mTmG mice were randomized to either condition 1. Tendon injury (control group) or 2. Tendon injury with Galectin-3 inhibitor (Gal3i) treatment at time of injury (treatment group). RESULTS: Histological analyses confirmed tendon thickening and collagen deposition after tendon injury and abrasion compared to control. Immunofluorescence showed higher levels of Col1 and α-SMA protein expression after injury compared to sham (*p<0.05). RT-qPCR also demonstrated increased gene expression of Col1 and α-SMA after injury compared to sham (*p<0.05). Gal3 protein expression also increased after injury and co-localized with α-SMA positive fibroblasts surrounding the fibrotic tendon. Gal3i treatment decreased collagen deposition and scarring observed in the treatment group (*p<0.05). Flow cytometry analysis further showed reduced numbers of profibrotic fibroblasts (CD26+) in the treatment compared to the control group (*p<0.05). CONCLUSIONS: Our study provides a reproducible and reliable model to investigate tendon fibrosis. Findings suggest the potential of Gal3i to overcome fibrosis resulting from tendon injuries.