# Intrahepatic Lymphangiogenesis Is Associated with Early Post-Hepatectomy Liver Regeneration, in Part via IL-6/STAT3 Signaling

## TL;DR

The study shows that liver regeneration after surgery is linked to lymphatic vessel growth, partly through the IL-6/STAT3 signaling pathway.

## Contribution

This study reveals a novel role of intrahepatic lymphangiogenesis in liver regeneration via IL-6/STAT3 signaling.

## Key findings

- Intrahepatic lymphatic vessels decrease shortly after surgery but recover by day 7.
- VEGF-C stimulation accelerates liver regeneration and repair.
- Blocking IL-6 reverses lymphangiogenesis-accelerated liver regeneration.

## Abstract

Background: Insufficient liver regenerative capacity poses life-threatening risks to patients following partial hepatectomy (PHx), and existing clinical treatments provide limited options for enhancing regeneration. Lymphatic vasculature plays essential roles in the immune response through the uptake and transport of pathogens, antigens, inflammatory mediators, and antigen-presenting cells. Recent research has shown that lymphangiogenesis may contribute to both heart and bone regeneration. However, the role and underlying mechanisms of intrahepatic lymphangiogenesis in liver regeneration remain unclear.

Methods: Single-cell RNA sequencing was employed to identify dynamic changes in lymphatic endothelial cells (LyECs) in liver tissues following 70% PHx. A mouse model of liver regeneration was utilized to assess the contribution of intrahepatic lymphangiogenesis to the regenerative process after 70% PHx. Additionally, an adeno-associated virus overexpressing vascular endothelial growth factor-C (AAV-VEGF-C) was used to confirm the role of intrahepatic lymphangiogenesis in liver regeneration. qRT-PCR, western blotting and immunofluorescence staining were performed to investigate the potential underlying mechanisms. Furthermore, a neutralizing rat anti-murine anti-IL-6 antibody (anti-IL-6) was used to verify signaling pathway.

Results: Single-cell RNA sequencing analysis revealed dynamic changes of LyECs in liver tissues following 70% PHx. Consistent with these findings, the number and area of intrahepatic lymphatic vessels (LVs) around the portal tract significantly decreased on postoperative day 3 (POD3) in the mouse model of 70% PHx compared to the sham group, but the number and area recovered by POD7. Additionally, vascular endothelial growth factor-C(VEGF-C), a pro-lymphangiogenic growth factor, was found to increase in the liver of the 70% PHx mouse model. Stimulation of lymphangiogenesis with AAV-VEGF-C significantly accelerated liver regeneration and repair. Mechanistically, intrahepatic lymphangiogenesis might accelerate liver regeneration by the activation of the IL-6/STAT3 pathway. Blocking IL-6 reversed lymphangiogenesis-accelerated liver regeneration.

Conclusions: Intrahepatic lymphangiogenesis may contribute to early liver regeneration after PHx, with partial dependence on IL-6/STAT3 signaling. These findings support further investigation of lymphatic-modulating approaches as potential adjuncts to enhance postoperative recovery after PHx, particularly in selected contexts.