Preconditioned Endothelialized Grafts Reduce Stenosis and Improve Vascular Remodeling in a Rat Pulmonary Artery Model.

Abstract

Pulmonary artery reconstruction is frequently required for congenital heart disease repair, yet current graft options remain limited by the scarcity of autologous conduits and the poor durability of synthetic grafts, which often fail due to thrombosis, stenosis, and calcification. Challenges are exacerbated in the hypoxic, low-pressure pulmonary circulation. Because a functional endothelium is critical for preventing thrombosis and neointimal hyperplasia, we engineered ready-to-use endothelialized tissue-engineered vascular grafts (TEVGs) using a stepwise shear-preconditioning regimen that mimics physiological pulmonary hemodynamics. Human induced pluripotent stem cell-derived endothelial cells (iPSC-ECs) were seeded onto decellularized vascular grafts and conditioned under pulsatile shear stress before implantation. Shear-preconditioned endothelialization improved graft compliance, reduced fibrinogen absorption, and increased endothelial resistance to hypoxic stress in vitro. We then evaluated graft performance in a rat pulmonary artery transplantation model designed to recapitulate the hypoxic and stenosis-prone environment of congenital heart disease. Shear-preconditioned endothelialized grafts maintained patency for one month, supported host cell repopulation, and promoted macrophage-mediated remodeling, whereas all control grafts developed severe stenosis. Patent grafts preserved lung alveolar architecture, while stenotic grafts resulted in exudative lung injury. These findings suggest that shear-preconditioned endothelialization may represent a strategy to generate functional vascular grafts for pulmonary artery reconstruction and establish a physiologically relevant small-animal platform for evaluating TEVG performance in congenital heart diseases. STATEMENT OF SIGNIFICANCE: Limited graft availability and the lack of functional endothelial layer remain key factors contributing to stenosis and graft failure in pulmonary artery reconstruction. Here, we reported development of an endothelialized tissue-engineered vascular graft (TEVG) generated through physiological shear-stress preconditioning to promote endothelial maturation and functional adaptation to the hypoxic, low-pressure pulmonary environment. To evaluate graft performance under physiologically relevant condition, we established a reproducible rat left pulmonary artery transplantation model. Compared with control grafts that developed severe stenosis, shear-preconditioned endothelialized TEVGs maintained luminal patency and showed graft recellularization at one month after implantation. This work presents a shear-preconditioned endothelialization strategy to enhance graft patency and remodeling for pulmonary circulation reconstruction in a physiologically relevant small animal model.