MicroRNA29a treatment improves early tendon injury

Tendon injuries (tendinopathies) are common in human and equine athletes and characterised by dysregulated collagen matrix resulting in tendon damage. We have previously demonstrated a functional role for miR29a as a post-transcriptional regulator of collagen 3 expression in murine and human tendon injury. Given the translational potential, we designed a randomised, blinded trial to evaluate the potential of a miR29a replacement therapy as a therapeutic option to treat tendinopathy in an equine model which closely mimics human disease. Tendon injury was induced in the superficial digital flexor tendon (SDFT) of 17 horses. Tendon lesions were treated one week later with an intralesional injection of miR29a or placebo. miR29a treatment reduced collagen 3 transcript levels at week 2 with no significant changes in collagen 1. Relative lesion cross-sectional area was significantly lower in miR29a tendons compared to control tendons. Histology scores were significantly better for miR29a treated tendons compared to control tendons. This data supports the mechanism of miRNA-mediated modulation of the early pathophysiologic events that facilitate tissue remodelling in the tendon after injury and provides strong proof of principle that a locally delivered miR29a therapy improves early tendon healing