Biomimetic double-layered electrospun nanofibrous scaffold with mussel adhesive protein coating and TGF-β3 encapsulation for enhanced tendon-bone healing in rotator cuff tears

Poor tendon-bone healing is a challenging issue and contributes to the high retear rate following rotator cuff tear (RCT) repair. The complex multiple tissue structure and limited chondrogenic capacity at the tendon-bone interface hinder effective regeneration and restoration of the enthesis. In this study, we developed a double-layered biomimetic nanofibrous scaffold encapsulating TGF-β3, further functionalized with a mussel adhesive protein (MAP) coating, to target the reconstruction of the torn rotator cuff's enthesis. The unique double-layer structure features distinct fibrous arrangements in each layer, mimicking the heterogeneous extracellular matrix structures of tendon and bone. This design provided a biomimetic environment conducive to the ingrowth of multiple tissues at the interface. In vitro studies demonstrated that the MAP-coated scaffold exhibited excellent biocompatibility and enhanced cell adhesion, facilitating tendon-bone interfacial integration. Moreover, the sustained release of TGF-β3 promoted stem cell recruitment and chondrogenic differentiation, as demonstrated both in vitro and in vivo. RNA-sequencing revealed that PI3K-Akt signaling pathway might be associated with the regulatory effects of the scaffold. In a rat RCT model, the composite scaffold significantly enhanced cartilage regeneration at the tendon-bone interface, restoring both enthesis structure and biomechanical properties. Therefore, the composite scaffold represents a promising strategy for improving tendon-bone healing and advancing interfacial tissue engineering in rotator cuff repair.