# 3D endothelial cell scaffolds protect liver explants and exhibit therapeutic effects on liver fibrosis

## TL;DR

3D endothelial cell scaffolds protect liver tissue and reduce liver fibrosis in mice, suggesting a potential therapy for liver disease.

## Contribution

Matrix-embedded endothelial cells (MEECs) demonstrate novel therapeutic effects on liver fibrosis and regeneration.

## Key findings

- MEECs preserved liver viability in explants from cirrhotic patients and fibrotic mice.
- MEECs reduced inflammation and fibrosis in mice by modulating macrophage polarization and hepatic stellate cell activation.
- MEECs promoted liver regeneration via secretion of hepatocyte growth factor and fibroblast growth factor 2.

## Abstract

Endothelial cells (ECs) display myriad protective roles that support tissue homeostasis. Embedding healthy ECs in 3D scaffolds stabilizes their phenotype to maximize reparative effects and shields immunogenicity. Here, we evaluate the protective effects of matrix-embedded ECs (MEECs) in liver explants and models of chronic liver disease.

Precision cut liver slices (PCLS) from patients with cirrhosis (n = 8) and fibrotic or healthy mice (n = 6) were co-cultured with MEECs for 24 h and hepatic viability and inflammation were analyzed. The protective effects of the MEECs secretome were explored in vitro. MEECs were perihepatically or subcutaneously implanted for 1 week in fibrotic mice with or without hepatectomy (n = 6) to evaluate their effects on liver inflammation, regeneration, and fibrosis.

MEECs protected liver viability in PCLS from patients with cirrhosis (ATP/protein, 2.7 vs. 5.0, p = 0.01) and fibrotic (5.3 vs. 7.1, p = 0.01) or healthy (7.8 vs. 10.6, p = 0.01) mice, and reduced injury-induced inflammation. MEECs produced hepatocyte growth factor and fibroblast growth factor 2, which were associated with improved hepatic viability and anti-inflammatory macrophage polarization, respectively. Perihepatic implantation of MEECs in fibrotic mice with or without hepatectomy reduced inflammation and hepatic damage and exhibited pro-regenerative and antifibrotic properties (Sirius red+ area, 8.3 vs. 6.4, p = 0.005). These antifibrotic effects were associated with higher production of heparan sulfate and metalloproteinases 2 and 9, and mitigation of hepatic stellate cell activation. Implantation of MEECs at a distance from the liver did not reduce liver injury, inflammation, or fibrosis.

Endothelial–hepatocyte regulation is essential in liver repair, and matrix-embedded endothelial cells (MEECs) appear to be a potential therapy for chronic liver injury and ex situ preservation of liver grafts.

Organ transplantation is the most effective therapy for advanced liver disease, yet remains limited by preservation of harvested graft viability and injury-induced inflammation post implantation. Healthy ECs display myriad protective roles that contribute to tissue homeostasis. In this study, we show how MEECs preserve cell viability and reduce inflammation in hepatic explants and display anti-inflammatory, antifibrotic and pro-regenerative properties in the liver of fibrotic mice. These dynamic and unique hepatoprotective properties of MEECs highlight their potential therapeutic utility for chronic liver injury or ex situ conservation of liver grafts.

Image 1

•MEECs preserve hepatic viability and protect from injury-induced inflammation.•MEECs ameliorate liver sinusoidal EC inflammatory phenotype.•FGF-2 released by MEECs induces an anti-inflammatory macrophage polarization.•MEECs reduce liver fibrosis by mitigating hepatic stellate cell activation.•MEECs drive hepatic regeneration, in part, through the secretion of hepatocyte growth factor.

MEECs preserve hepatic viability and protect from injury-induced inflammation.

MEECs ameliorate liver sinusoidal EC inflammatory phenotype.

FGF-2 released by MEECs induces an anti-inflammatory macrophage polarization.

MEECs reduce liver fibrosis by mitigating hepatic stellate cell activation.

MEECs drive hepatic regeneration, in part, through the secretion of hepatocyte growth factor.