Biomimetic <i>de novo</i> construction of hierarchically aligned and gradient-mineralized collagen for tendon-bone integrated regeneration.

Abstract

The tissues spanning from tendon to bone exhibit a highly specialized extracellular matrix (ECM) architecture, characterized by hierarchical collagen alignment and a gradient mineral composition, which together enable efficient force transfer and guide spatially organized cellular phenotypes. However, recapitulating such complex multi-scale organization and compositional gradients to achieve integrated soft-hard tissue remains challenging. Here, we report the <i>de novo</i> construction of biomimetic collagen-mineral matrices that mimic both the hierarchical organization and mineral gradient distribution of the native tendon-to-bone ECM. Through synergistic electro-assembly and post-treatment, collagen molecules self-organized into aligned fibrillar matrices with multi-scale architecture, replicating tendon-side morphology while providing robust tensile mechanics. At the opposing end, intrafibrillar and interfibrillar minerals were spatially patterned to emulate the mineral gradient from tendon to bone. This structural and compositional continuum enables smooth mechanical transition across the soft-hard tissue interface and promotes region-specific regeneration of aligned tendon-like tissue, fibrocartilage and bone. <i>In vivo</i> studies in rabbit models confirm that these <i>de novo</i> constructed matrices support histological reconstruction of multiple tissues from tendon to bone at the rotator cuff, and significantly improve functional recovery. This work presents a bottom-up biomimetic strategy for engineering multiscale collagen-based scaffolds and demonstrates the therapeutic potential of <i>de novo</i> constructed matrices for multiple tissue regeneration.