The Effect of Administration of Double Stranded MicroRNA-210 on Acceleration of Achilles Tendon Healing in a Rat Model

Background: Achilles tendons heal slower than other tissues, therefore requiring the developmnent of a strategy for accelerating the process. Vascular supply plays an important role in primary tendon healing, especially during the early healing phase. MicroRNA (miR)-210 has been reported as being crucial for angiogenesis, which is a key factor of tissue repair. We report herein that local injection of synthetic miR-210 into the injured Achilles tendon of a rat accelerated healing of the tendon.

Methods: Achilles tendons were transected and repaired via the Kessler suture technique in Sprague-Dawley rats. Then, double stranded (ds) miR-210 was injected into the repaired sites. The control group was injected with non-functioned dsRNA. At 2, 6 and 12 weeks, histological evaluations were performed. At two and six weeks, mechanical testing and angiogenesis were evaluated. Gene expression analysis using real-time polymerase chain reaction (PCR) and immunohistochemistry were performed at two weeks.

Result: At two and six weeks, regular dense collagen tissue in the miR-210 group was observed and the diameter of collagen fiber in the miR-210 group was significantly higher than in the control. At two weeks, the ultimate failure load was significantly higher than in the control group, and expression of VEGF, FGF2 and type I collagen was upregulated. Abundant vessels in the miR-210 group were observed at two weeks, but there was no significant difference in vessel numbers between the two groups at six weeks. At 12 weeks, repaired Achilles tendons in the miR-210 group consisted of parallel and dense fibers, whereas wavy and loose fibers were still observed in the control group.

Conclusion: The current study showed that single local injection of synthetic miR-210 promotes Achilles tendon healing in the early phase.