Bone mesenchymal stem cells attenuate hepatic stellate cell activation and liver fibrosis through REDD1/autophagy pathway.

Background: Bone mesenchymal stem cells (BMSCs) have demonstrated therapeutic potential in attenuating liver fibrosis. However, the precise molecular targets through which BMSCs regulate hepatic stellate cells (HSCs) activation, as well as liver fibrosis remains unclear.

Methods: BMSCs were isolated from rat bone marrow, cultured, and characterized. BMSCs were administered via tail vein injection into bile duct ligation (BDL)-induced liver fibrosis mice. The downstream target of BMSCs was analyzed using RNA-sequencing (RNA-seq) and detected in liver tissues of Primary Biliary Cholangitis (PBC) patients and mice liver fibrosis. Mechanistic evaluations were employed using immunofluorescence, Western blot, RT-qPCR, transmission electron microscope (TEM), and histological analyses.

Results: BMSCs transplantation markedly attenuated liver fibrosis. RNA-seq revealed Regulated in Development and DNA Damage Response 1 (REDD1) is a novel regulator of BMSCs-based antifibrotic liver fibrosis therapy and upregulated in liver tissues of PBC patients and mice liver fibrosis. Mechanistically, REDD1 overexpression suppressed HSCs activation by impairing HSCs autophagy, thereby potentiating BMSCs therapeutic efficacy. More importantly, the in vivo experiments revealed REDD1 treatment ameliorated liver function, alleviated liver injury, and attenuated liver fibrosis, and PI3K/AKT/mTOR and TGFβ/Smad3 pathway were involved in the regulation.

Conclusions: Our results provide preliminary evidence for the protective roles of BMSCs in liver fibrosis through REDD1/autophagy pathway and suggest that REDD1 may be a promising therapeutic target for treating liver fibrosis.