Title : Sphingosine-1-Phosphate (S1P) in whole liver recellularization improves endothelization of acellular liver scaffold
Abstract:
Endothelialization is crucial for tissue bioengineering, particularly in developing functional blood vessel linings to ensure proper vascularization. Effective re-endothelialization of the vasculature in bioengineered organs is challenging, often leading to blood coagulation and hindering successful engraftment. Endothelial cell proliferation, migration, and angiogenesis are essential processes for constructing functional, vascularized bioengineered organs. Sphingosine-1-phosphate (S1P), a low molecular weight phospholipid mediator, regulates various biological activities in endothelial cells, including survival, proliferation, and cell barrier integrity.
In this study, we present a novel approach to enhance the re-endothelialization of decellularized rat liver scaffolds by seeding Human Umbilical Vein Endothelial Cells (HUVECs) in the presence of S1P, aiming to bioengineer a fully endothelialized liver. Initially, we validated the effects of S1P on HUVECs in a two-dimensional cell culture system, confirming that S1P significantly promotes endothelial functions. Following this validation, we seeded HUVECs in the presence of S1P into decellularized rat liver scaffolds via the portal vein and maintained in perfusion bioreactor for 7 days. Longitudinal assessment using the resazurin reduction assay revealed significantly improved cell proliferation in S1P-treated scaffolds. Histological and molecular analyses confirmed efficient and uniform endothelial coverage of vascular structures. Functional evaluation, including ex vivo whole blood perfusion and heterotopic implantation, demonstrated reduced thrombogenicity and preserved vessel integrity in S1P-treated constructs.
Our results indicate that S1P is a key regulator of endothelialization processes, promoting HUVEC proliferation, survival, and facilitating the formation of a functional endothelial layer on the vascular structure of re-endothelialized liver scaffold. These findings highlight the pivotal role of S1P as a promising approach for generating vascularized bioengineered livers suitable for transplantation.
Keywords: Bioengineered liver, S1P, HUVECs, Endothelialization, Proliferation
