Human Amniotic Epithelial Cell Transplantation Induces Markers of Alternative Macrophage Activation and Reduces Established Hepatic Fibrosis

Ursula Manuelpillai,Vijesh Vaghjiani,Dinushka Lourensz,James Chan,Jorge Tchongue,William Sievert,Alexander Hodge,Derek Lacey,Padma Murthi,Jing-Yang Tee,Partha Mukhopadhyay

doi:10.1371/journal.pone.0038631

Abstract

Chronic hepatic inflammation from multiple etiologies leads to a fibrogenic response that can progress to cirrhosis and liver failure. Transplantation of human amniotic epithelial cells (hAEC) from term delivered placenta has been shown to decrease mild to moderate hepatic fibrosis in a murine model. To model advanced human liver disease and assess the efficacy of hAEC therapy, we transplanted hAEC in mice with advanced hepatic fibrosis. Immunocompetent C57BL/6 mice were administered carbon tetrachloride (CCl4) twice weekly resulting in bridging fibrosis by 12 weeks. hAEC (2×106) were infused via the tail vein at week 8 or weeks 8 and 10 (single and double dose, respectively). Human cells were detected in mouse liver four weeks after transplantation showing hAEC engraftment. CCl4 treated mice receiving single or double hAEC doses showed a significant but similar decrease in liver fibrosis area associated with decreased activation of collagen-producing hepatic stellate cells and decreased hepatic protein levels of the pro-fibrogenic cytokine, transforming growth factor-beta1. CCl4 administration caused hepatic T cell infiltration that decreased significantly following hAEC transplantation. Hepatic macrophages play a crucial role in both fibrogenesis and fibrosis resolution. Mice exposed to CCl4 demonstrated increased numbers of hepatic macrophages compared to normal mice; the number of macrophages decreased significantly in CCl4 treated mice given hAEC. These mice had significantly lower hepatic protein levels of the chemokine monocyte chemoattractant protein-1 than mice given CCl4 alone. Alternatively activated M2 macrophages are associated with fibrosis resolution. CCl4 treated mice given hAEC showed increased expression of genes associated with M2 macrophages including YM-1, IL-10 and CD206. We provide novel data showing that hAEC transplantation induces a wound healing M2 macrophage phenotype associated with reduction of established hepatic fibrosis that justifies further investigation of this potential cell-based therapy for advanced hepatic fibrosis.

Highlights

Chronic hepatic inflammation from diverse causes including alcohol, steatohepatitis, autoimmune disease and viral infection leads to a wound healing, pro-fibrogenic response
In order to gain an understanding of potential anti-fibrotic mechanisms, we studied the effects of human amniotic epithelial cells (hAEC) transplantation on hepatic macrophages that play a pivotal role in mediating fibrogenesis and fibrosis resolution [18,19]
We found that CCl4-treated mice which had been infused with hAEC had increased mRNA expression of M2 associated markers YM-1 (P,0.05), CD206 and IL-10 (P,0.01; Figure 4A) compared with mice given CCl4 alone

Summary

Introduction

Chronic hepatic inflammation from diverse causes including alcohol, steatohepatitis, autoimmune disease and viral infection leads to a wound healing, pro-fibrogenic response. In some patients with ongoing liver injury, this response can progress to cirrhosis, portal hypertension and liver failure [1] These outcomes are associated with a significant mortality rate for which liver transplantation is the only curative therapy [2,3]. We have shown that transplantation of placenta derived human amniotic epithelial cells (hAEC) into immunocompetent mice with carbon tetrachloride (CCl4) induced liver fibrosis can constrain hepatic fibrogenesis [13]. This outcome may be related to several factors linked to hAEC transplantation including reduction in the expression of pro-inflammatory and pro-fibrogenic cytokines coupled with the induction of matrix metalloproteinases to promote a collagen-degrading environment [13]

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Results

Conclusion