# Conversion of Transplanted Mature Hepatocytes into Afp + Reprogrammed Cells for Liver Regeneration After Injury

## TL;DR

This study reveals how transplanted mature liver cells regenerate the liver by converting into specialized cells that can both multiply and mature, offering new insights for liver repair therapies.

## Contribution

The study identifies a novel metabolic and signaling mechanism by which transplanted hepatocytes regenerate the liver.

## Key findings

- Donor hepatocytes convert into Afp+ reprogrammed hepatocytes that can proliferate and mature.
- PPARγ and AFP regulate metabolic remodeling, creating distinct subpopulations for proliferation and survival.
- TNF-α/AP-1 signaling from host neutrophils supports the proliferation of reprogrammed hepatocytes.

## Abstract

Hepatocyte transplantation effectively treats liver failure, yet the regenerative mechanisms driven by engrafted mature hepatocytes remain elusive. Through integrated serial transplantation, lineage tracing, single‐cell RNA sequencing (scRNA‐seq), and single‐cell transposase‐accessible chromatin sequencing (scATAC‐seq), we show that donor hepatocytes convert into transitional, alpha‐fetoprotein‐positive reprogrammed hepatocytes (Afp+
rHeps). These cells exhibit controlled proliferation while maintaining unipotent hepatic differentiation potential, enabling fully functional maturation after rapid expansion. Such plasticity is dynamically regulated by AFP expression level‐dependent metabolic remodeling through the peroxisome proliferator‐activated receptor γ (PPARγ) pathway, which coordinates two functionally distinct subpopulations: Afp
low cells sustain proliferation by activating energy metabolism pathways, whereas Afp
high cells adapt to stress by switching to β‐oxidation. Additionally, the proliferation of Afp+
rHeps is driven and sustained by tumor necrosis factor‐alpha (TNF‐α)/activator protein‐1 (AP‐1) signaling derived from host liver neutrophils. Spatiotemporal analysis further shows that transforming growth factor‐beta (TGF‐β)‐mediated migration precedes PPAR‐driven metabolic zonation, ensuring ordered niche adaptation. Together, these findings delineate the molecular basis of liver regeneration mediated by transplanted mature hepatocytes and pinpoint the PPARγ/AFP metabolic axis and TNF‐α/AP‐1 mitogenic signaling as actionable levers to optimize regenerative therapies based on terminally differentiated hepatocytes.

Donor‐derived tdTomato+ mature hepatocytes were FACS‐isolated and transplanted into Fah
−/− host mice. During regeneration, these cells convert into proliferative, unipotent Afp+
rHeps. Their plasticity is governed by a PPARγ/AFP‐dependent metabolic switch, segregating into pro‐proliferative Afp
low and pro‐survival Afp
high subpopulations. Neutrophil‐derived TNF‐α/AP‐1 signaling drives and sustains Afp+
rHep proliferation. Over the course of repopulation, progressive reconstruction of liver zonation is achieved.