Endothelial Hydrogels Improve Microvascular Regeneration and Perfusion in Tracheal Scaffolds.

Abstract

Vascularization remains a major barrier to the clinical translation of airway replacement. We previously demonstrated that engineered tracheal scaffolds support neovascularization, although restoration of microvascular perfusion is delayed in part due to a reduction in capillary branching. Endothelial hydrogels (EH) have demonstrated the potential to enhance vascular regeneration in several domains of tissue engineering, yet their application in airway replacement has not been fully evaluated. In this study, we assessed the impact of EH on microvascular regeneration and perfusion in tracheal scaffolds. Tracheal scaffolds were fabricated from C57BL/6J mice. EH were formulated with endothelial cells (EC) from human or mouse lineages and collagen, then applied to tracheal scaffolds. EH-scaffolds were cultured ex vivo for 7 days and stained with CD31, DAPI, lectin-FITC, and vascular endothelial growth factor (VEGF). The optimal EH composition was evaluated in vivo using orthotopic tracheal transplantation. At 1-month, microvascular regeneration was quantified, patterning was assessed via Sholl analysis, and perfusion was quantified using lectin-FITC. EH supported EC attachment on tracheal scaffolds. The ideal EH composition for maximal EC coverage was 3.6 × 10⁶ cells/cm² and 1.25 mg/mL collagen. EC expressed VEGF and formed microvascular networks on tracheal scaffold ex vivo. EH-scaffolds were successfully implanted without signs of respiratory distress or obstruction. Compared to control, EH-scaffolds improved graft perfusion and microvascular patterning in tissue engineered trachea. EH enhances microvascular regeneration and perfusion of engineered tracheal scaffolds in vivo, thus supporting the potential of EH as a strategy to accelerate vascular regeneration in airway reconstruction. N/A.