A regeneration process-matching scaffold with appropriate dynamic mechanical properties and spatial adaptability for ligament reconstruction

Ligament regeneration is a complicated process that requires dynamic mechanical properties and allowable space to regulate collagen remodeling. Poor strength and limited space of currently available grafts hinder tissue regeneration, yielding a disappointing success rate in ligament reconstruction. Matching the scaffold retreat rate with the mechanical and spatial properties of the regeneration process remains challenging. Herein, a scaffold matching the regeneration process was designed via regulating the trajectories of fibers with different degradation rates to provide dynamic mechanical properties and spatial adaptability for collagen infiltration. This core-shell structured scaffold exhibited biomimetic fiber orientation, having tri-phasic mechanical behavior and excellent strength. Besides, by the sequential material degradation, the available space of the scaffold increased from day 6 and remained stable on day 24, consistent with the proliferation and deposition phase of the native ligament regeneration process. Furthermore, mature collagen infiltration and increased bone integration in vivo confirmed the promotion of tissue regeneration by the adaptive space, maintaining an excellent failure load of 67.65% of the native ligament at 16 weeks. This study proved the synergistic effects of dynamic strength and adaptive space. The scaffold matching the regeneration process is expected to open new approaches in ligament reconstruction.