Dual-signal in situ programming of CD14+ monocytes enables rapid endothelialization and vascular regeneration

Coronary artery disease creates a major need for effective small-diameter vascular grafts, yet long-term performance remains limited by inadequate and unstable endothelialization. Building on prior cell-free graft studies showing that circulating monocytes can contribute to endothelialization, we developed a functionally graded coaxial fiber platform to test an adhesion–instruction design for in situ vascular regeneration. Four scaffold types were engineered: inert scaffold (IS, poly(ε-caprolactone)/PCL only), amniotic membrane-functionalized scaffold (AP, PCL core + dAM/PCL shell; in vitro only), permissive scaffold (PS, PCL core + dAM/PCL/heparin shell), and instructive scaffold (InS, PCL core + dAM/PCL/heparin/VEGF shell). The design combined a slowly degrading PCL core for long-term mechanical support with a faster-degrading bioactive shell composed of dAM and PCL, which provided early adhesive and hemocompatible cues while enabling sustained VEGF presentation. In vitro , the dAM-based microenvironment supported CD14 + monocyte adhesion and endothelial-like programming, whereas integrin inhibition suppressed this process. In a rat abdominal aorta interposition model, InS grafts achieved faster endothelial coverage than IS and PS grafts and showed improved long-term lumen preservation. This early endothelialization was associated with enhanced smooth-muscle regeneration, more favorable immune remodeling, and improved vascular wall reconstruction. In vivo VEGFR2 blockade further attenuated the endothelial-like transition of recruited CD14 + cells, supporting VEGF signaling as an instructive component. Together, these findings support a scaffold-based design concept in which a functionally graded coaxial core-shell platform spatially and temporally integrates adhesive and instructive signals to promote rapid endothelialization and vascular regeneration in small-diameter vascular grafts.