Human Amnion Epithelial Cells Produce Soluble Factors that Enhance Liver Repair by Reducing Fibrosis While Maintaining Regeneration in a Model of Chronic Liver Injury

Abstract

Human amnion epithelial cells (hAECs) exert potent antifibrotic and anti-inflammatory effects when transplanted into preclinical models of tissue fibrosis. These effects are mediated in part via the secretion of soluble factors by hAECs which modulate signaling pathways and affect cell types involved in inflammation and fibrosis. Based on these reports, we hypothesized that these soluble factors may also support liver regeneration during chronic liver injury. To test this, we characterized the effect of both hAECs and hAEC-conditioned medium (CM) on liver repair in a mouse model of carbon tetrachloride (CCl4)-induced fibrosis. Liver repair was assessed by liver fibrosis, hepatocyte proliferation, and the liver progenitor cell (LPC) response. We found that the administration of hAECs or hAEC-CM reduced liver injury and fibrosis, sustained hepatocyte proliferation, and reduced LPC numbers during chronic liver injury. Additionally, we undertook in vitro studies to document both the cell–cell and paracrine-mediated effects of hAECs on LPCs by investigating the effects of co-culturing the LPCs and hAECs and hAEC-CM on LPCs. We found little change in LPCs co-cultured with hAECs. In contrast, hAEC-CM enhances LPC proliferation and differentiation. These findings suggest that paracrine factors secreted by hAECs enhance liver repair by reducing fibrosis while promoting regeneration during chronic liver injury.

Addressing the liver progenitor cell response and hepatic oxidative stress in experimental non-alcoholic fatty liver disease/non-alcoholic steatohepatitis using amniotic epithelial cells

“…This indicates that other factors including Wnt ligands recently reported to be produced by hAECs [38] may still persist to drive the LPC response in liver homeostasis and repair [39]. Furthermore, in combination with our recent report that hAECs can promote LPC proliferation and differentiation in vitro and in the absence of inflammatory cytokines [26], these findings support the notion that hAECs support liver repair and reduce inflammation. It is also noteworthy that hAECs reduce LPC mitogens in this context given that uncontrolled proliferation and growth of LPCs can lead to the development of liver cancer [40][41][42].…”

“…*P < 0.05, **P < 0.01, ***P < 0.001. FF, NASH diet alone; FFHD, NASH diet with double hAEC dose; FFHS, NASH diet with single hAEC dose like weak inducer of apoptosis (TWEAK) [5,7,26,[34][35][36][37]. We have shown a reduction in both LPC numbers and expression levels of the LPC mitogens IL-6, IFNγ and TWEAK in hAEC treated mice most likely related to a concomitant reduction in activated hepatic macrophages.…”

“…We have shown a reduction in both LPC numbers and expression levels of the LPC mitogens IL-6, IFNγ and TWEAK in hAEC treated mice most likely related to a concomitant reduction in activated hepatic macrophages. While hAECs increased LPC proliferation in in vitro co-culture studies [26], the reduction in LPC response was again most likely achieved by hAEC reduction of hepatic macrophages [24] and their secreted LPC mitogens. We have observed this consistently in previous studies using in vivo liver and lung injury models that have demonstrated that hAECs reduce macrophage recruitment and support a predominant alternatively activated (M2) phenotype [18,19].…”

“…Immortalised mouse macrophages (iMACs) and bipotential murine oval liver cells (BMOLs), a mouse LPC cell line, were co-cultured with hAECs from 4 donors, in 0.4 μm transwell inserts, in 6-well plates at a 1:5 ratio. Wells containing only iMACs or BMOLs served as negative controls and were maintained in DMEM:F12 supplemented with 5-10% FBS or DMEM:F12 supplemented with 30 ng/mL IGF-II, 50 ng/mL EGF, 10 μg/mL insulin, 100 U/mL penicillin and streptomycin and 5-10% FBS, respectively [26]. Cells treated with 5,6-dimethylxanthenone-4-acetic acid (DMXAA-D5817, Sigma-Aldrich, St.…”

“…The therapeutic potential of hAECs has been explored in the setting of liver [18], lung [19], cardiac [20], epidermal [21] and neurological injury [22]. We [16,18,[23][24][25][26] and others [27,28] postulate that hAECs may be a promising alternative to address NAFLD/NASH either through the restriction of hepatocyte death and hepatic stellate cell activation [24] and/or through the modification of dominant macrophage phenotyp e [18,24]. Both hAECs and their secretome have been shown to reduce chronic liver injury [23,24].…”