(507) Endothelial hydrogel improves long-term microvascular regeneration and perfusion in engineered tracheal grafts

Introduction: Establishing durable microvascular perfusion remains a critical barrier in airway transplantation. Insufficient sustainable revascularization can cause anastomotic dehiscence, graft ischemia, and tracheomalacia. While partially decellularized tracheal grafts (PDTG) support host microvascular ingrowth, prior studies demonstrated inadequate long-term perfusion. We aimed to enhance durable microvascular regeneration and perfusion in PDTG using endothelial hydrogel (EH) in an orthotopic mouse model.

Methods: PDTG were engineered from C57BL/6J mice. EH was formulated with primary mouse lung endothelial cells in collagen, then seeded to PDTG. EH-seeded grafts (N=5) and collagen-only grafts (control, N=4) were cultured ex vivo for 7 days prior to orthotopic implantation. Grafts were harvested at 3 months post-implantation for whole-mount analysis. Microvascular regeneration was assessed by CD31 immunostaining, vascular network complexity by Sholl analysis, and functional perfusion by lectin-FITC labeling.

Results: EH caused no respiratory distress or airway obstruction; all animals survived to 3-month endpoint. EH significantly enhanced microvascular regeneration, achieving levels comparable to host trachea. Sholl analysis demonstrated increased microvascular intersections in EH-seeded grafts at anastomotic, cartilaginous, and intercartilaginous regions (all p< 0.0001) compared to control. Functional perfusion was higher in EH grafts (18.64±3.43%) than in control (9.21±1.75%; p=0.0016) and was comparable to host trachea (16.60±3.33%).

Conclusions: EH seeding establishes durable microvascular regeneration and sustained functional perfusion in engineered tracheal grafts in vivo, supporting its potential to improve long-term graft viability and outcomes in airway reconstruction.