Bionic Functional Surgical Suture with Hierarchical Micro–Nano Dimensions for Rotator Cuff Repair: Inducing Process-Matching Mechanobiological and Biological Responses Adapted to the Regeneration

Abstract

Surgical sutures are necessary for the rotator cuff (RC) repair to reconnect the torn and degenerating cuff tendon to its footprint. Early-stage immunomodulation, angiogenesis, and the progressive mechanobiological response encourage complex healing processes involving micro-nano dimensional reconstruction, including tendon-bone interface integration and tendon remodeling. However, commercially available sutures with mismatched micrometer-scale diameters resulted in mechanobiological and biological deficiencies, severely impeding RC regeneration. We developed a bionic functional surgical suture (SS) with helical and hierarchical micro-nano structures using nano- and micro-Poly (DL-lactide-co-glycolide) (PLGA) yarns (ny), which was subsequently crosslinked in situ with a temporary chemotactic (TC) layer of physiological fibrin networks (TC-nySS). The TC-nySS has both mechanobiological and biological advantages: 1) biomimetic helical and hierarchical micro-nano structures showed progressive degradation behavior, inducing the incremental mechanobiological response of the repaired tissues; 2) outer TC layer of biochemical modification by fibrin networks supplied dual-functions of angiogenesis and immunomodulation at the early stage, subsequently resulting in timely vascularization and inflammatory regressions due to superior degradation behavior of the constructs. Consequently, TC-nySS with structural and biochemical designs that elicit process-matching mechanobiological and biological responses tailored to the RC regeneration successfully achieved the complex healing processes, including superior tendon-bone interface integration and tendon remodelling.