Nanoparticle-coated sutures providing sustained growth factor delivery to improve the healing strength of injured tendons

ABSTRACT Tendon injuries are common diseases. The healing capacity of tendon is limited due to its special composition of extra-cellular matrix and hypocellularity and hypovascularity. The purpose of this study was to evaluate the effectiveness of nanoparticle-coated sutures carrying growth factors for accelerating tendon repair. A variety of experimental methods had been used to investigate the characteristics and therapeutic effects of the modified sutures. Nanoparticles could adhere uniformly to the surface of the suture through polydopamine. Even sutured in the tendon, most of nanoparticles were still remained on the surface of suture, and the loaded proteins could spread into the tendon tissues. In vivo study, the ultimate strength of repaired tendons treated with bFGF and VEGFA-releasing sutures was significantly greater than the tendons repaired with control sutures at multiple time-points, whether in the chicken model of flexor tendon injury or the rat model of Achilles tendon injury. At week 6, the adhesion score in the bFGF and VEGFA-releasing suture group was significantly lower than those of the control suture group. Tendon gliding excursion was significantly longer in the bFGF and VEGFA-releasing suture group than that in the control bare sutures. Work of digital flexion was significantly decreased in the bFGF and VEGFA-releasing suture group. In a word, we developed a platform for local and continuous delivery of growth factors based on the nanoparticle-coated sutures, which could effectively deliver growth factors to tissues and control the release of growth factors. This growth factors delivery system is an attractive therapeutic tool to repair injured tendons.