Bioengineered MSC Transplantation Alleviates Hepatic Fibrosis by Regulating Mammalian Target of Rapamycin Signaling

Hepatic fibrosis is the pathological change during chronic liver diseases (CLD) that turns into cirrhosis if not reversed timely. Allogenic mesenchymal stem cell (MSC) therapy is an alternative to liver transplantation for CLD. However, poor engraftment of the transplanted MSCs limits their therapeutic efficacy. MSCs express chemokine receptors that regulate their physiology. We observed several-fold increased expressions of Cxcl3 and decreased expression of Mmp13 in the fibrotic liver. Therefore, we bioengineered MSCs with stable overexpression of Cxcr2 (CXCL3-cognate receptor) and Mmp13, collagenase (MSC). The CXCL3/CXCR2 axis significantly increased migration through the activation of AKT/ERK/mTOR signaling. These bioengineered MSCs transdifferentiated into hepatocyte-like cells (MSC-HLCs) that endured the drug-/hepatotoxicant-induced toxicity by significantly increasing the antioxidants-Nrf2 and Sod2, while decreasing the apoptosis-Cyt C, Casp3, Casp9, and drug-metabolizing enzyme-Cyp1A1, Cyp1A2, Cyp2E1 markers. Therapeutic transplantation of MSC abrogated AAP-/CCl₄-induced hepatic fibrosis in mice by CXCR2-mediated targeted engraftment and MMP-13-mediated reduction in collagen. Mechanistically, induction of CXCL3/CXCR2 axis-activated mTOR-p70S6K signaling led to increased targeted engraftment and modulation of the oxidative stress by increasing the expression and activity of nuclear Nrf2 and SOD2 expression in the regenerated hepatic tissues. A marked change in the fate of transplanted MSC toward hepatocyte lineage demonstrated by co-immunostaining of GFP/HNF4α along with reduced COL1α1 facilitated the regeneration of the fibrotic liver. Our study suggests the therapeutic role of allogenic Cxcr2/Mmp13-bioengineered MSC transplantation decreases the hepatic oxidative stress as an effective translational therapy for hepatic fibrosis mitigation-mediated liver regeneration.