Abstract 16738: Reendothelization of a Pediatric-Sized Decellularized Heart Using Cells Grown in a Closed Expansion System

Abstract

Background: Coagulation is a significant issue in bioengineering of vascularized tissues. Reendothelization is a strategy commonly used to prevent it in bioartificial organs. However, the large number of cells required for full coverage of blood vessels in a human-sized heart is a bottleneck in this field. Closed cell expansion systems (e.g., Quantum Cell Expansion System, QES) may provide a solution to this issue. The goal of this work was to reendothelize a pediatric-sized decellularized heart using human induced pluripotent stem cell-derived endothelial cells (hiPSC-dEC). Methods: hiPSC-dEC were expanded using the QES and cultivated with decellularized cardiac patches or perfused into whole decellularized rabbit hearts. Reendothelized cardiac patches and whole hearts were evaluated by live/dead staining, histology, scanning electron microscopy (SEM) and immunofluorescence. Results: Our results demonstrated that QES induced exponential iPSC-dEC growth, producing 36.14x10e7 ± 2.34x10e7 cells after 5-9 days (n=13). After cell expansion, these cells expressed von Willebrand Factor (vWF) and CD31, maintaining the phenotype of the endothelial cells. They also retained the capacity of cell-cell interaction evaluated by VE-cadherin staining. Rabbit hearts (8 ± 1.3 grams) were decellularized by whole organ perfusion. Decellularized hearts were grossed to produce cardiac patches (n=9) or were recannulated in a customized closed apparatus with controlled temperature and gas exchange for recellularization (for whole organ recellularization, n=6). Expanded hiPSC-dECs were attached (74.9 ± 2.9%) to cardiac patches, forming vessel-like structures, surviving for at least 17 days in the patches. These patch studies were used to extrapolate the number of cells, the frequency of medium exchange and cell attachment and orientation needed for decellularized hearts. Based on these data, one hundred million hiPSC-dEC were perfused into the whole decellularized rabbit heart through the coronary trees and cultivated for 7 days. Recellularized hearts showed that cells selectively attached to the small and large vessels and the endocardium but were not observed outside of vessels. Conclusion: Together, these findings demonstrate that hiPSC-dEC expanded in a system can repopulate pediatric-size hearts by covering vessel walls and thus provide a favorable environment to prevent coagulation after transplantation.