Abstract
Background: Chronic liver disease is characterised by progressive hepatocyte injury, inflammation and accumulation of extracellular matrix. Liver progenitor cells (LPC) are bipotent cells induced during liver injury that can regenerate both hepatocytes and cholangiocytes. In addition, macrophages play a pivotal role in fibrogenesis and fibrosis resolution. Classically, macrophages are classified into M1 (pro-inflammatory macrophages) and M2 (pro-resolution macrophages). Recently, Ly6C expression has been used to identify distinct macrophage populations, Ly6Chi (inflammatory) and Ly6Clow (resolution). We are developing a therapy for chronic liver fibrosis using human amnion epithelial cells (hAECs). The choline-deficient ethionine-supplemented (CDE) diet is a non-invasive and quick method to induce liver injury and LPC proliferation. Here, we aimed to investigate the effect of hAECs on macrophages and LPC during liver injury induced by a CDE diet.
Methods, Results & Conclusion Methods: C57/B16J mice were commenced on a CDE diet, then 2 or 4 million hAECs were infused intraperitoneally 24h later and the CDE diet continued. Outcomes were assessed at days 1, 3, 5, 14, 21 and 42 following hAEC administrations. Sirius red staining and immunohistochemistry were used to determine fibrosis and identify LPC in liver sections. Macrophages and LPC were further identified and characterised using flow cytometery sorting and PCR.
In CDE treated mice, hAEC significantly reduced liver fibrosis compared to untreated mice. hAEC decreased the number of proinflammatory (Ly6Chi) monocyte-derived macrophages (MDM) and increased the number of anti-inflammatory and tissue remodelling (Ly6Clow) MDM. hAEC also enhanced the expression of matrix-metalloproteinase (MMP)12 and MMP13 in Ly6CLow sorted cells. LPC numbers were reduced significantly in hAEC treated mice.
Our data confirm the potential efficacy of hAECs as an effective therapy in liver fibrosis.