In Situ Vascularization and Epithelialization of Segmental Bioengineered Trachea Based on Marrow-Derived Stem/Progenitor Cells

The success of tracheal transplantation depends on the rapid establishment of vascularization and epithelialization to support functional tissue formation. This study presents an innovative approach for in situ transplantation of a biomimetic tracheal graft, integrating microvascularization and epithelialization. First, endothelial progenitor cells (EPCs) and mesenchymal stem cells (MSCs) were isolated and purified from bone marrow, serving as seed cells for graft vascularization and epithelialization. Next, 3D printing was employed to create a bilayered tracheal graft using poly(ε-caprolactone) (PCL) and decellularized tracheal extracellular matrix (dtECM), which provided both optimal biomechanical properties and angiogenic potential. MSCs and EPCs were seeded on the inner and outer surfaces of the graft, respectively, and implanted in a long-segment in situ transplantation model. Six months post-transplantation, CT scans revealed a patent luminal space, bronchoscopy confirmed successful anastomosis, scanning electron microscopy showed abundant cilia on the inner graft surface, and α-SMA immunofluorescence demonstrated significant neovascularization. The PCL/dtECM graft exhibited excellent biomechanical properties, along with enhanced cell adhesion and proliferation. The combination of EPCs and MSCs effectively promoted both vascularization and epithelialization, ensuring successful graft integration and long-term survival of the experimental animals.