An all silk-derived functional system promotes tendon regeneration by regulating cell fate of tendon stem/progenitor cells in inflammatory microenvironment

The dysregulation of the tissue’s inflammatory microenvironment following an injury plays a crucial role in attenuating tendon regeneration capacity. In this study, we integrated silk fibroin (SF) nanospheres (NS) loaded with the anti-inflammatory protein recombinant α-Klotho (rKL) into a biomimetic aligned SF scaffold (ASF). This created an all-silk-derived functional scaffold (rKL@NS-ASF) with biomimetic physical structure and biological activity, designed to regulate the inflammatory microenvironment and facilitate tendon regeneration. Proteomic analysis revealed that rKL preserves the tenogenic differentiation potential of tendon stem/progenitor cells (TSPCs) by mitigating the oxidative stress response in a tumor necrosis factor-alpha (TNF-α)- induced inflammatory microenvironment in vitro. The rKL@NS-ASF scaffold, along with the PBS@NS-ASF control group, was successfully fabricated and exhibited remarkable drug loading/release capabilities and excellent biocompatibility in vitro. In a rat full-cut Achilles tendon defect model, the rKL@NS-ASF scaffold exhibited a reduction in inflammatory cells infiltration and promoted fibroblast infiltration compared to the PBS@NS-ASF group at 4 weeks post-operation. At 8 weeks post-operation, tendons treated with the rKL@NS-ASF scaffold exhibited increased collagen fiber deposition and effectively suppressed heterogeneous ossification, thereby facilitating tendon regeneration and functional recovery. In conclusion, this all-silk-derived functional system creates a favorable microenvironment to promote tendon regeneration.