Objective Until now, the hepatic differentiation of embryonic stem cells (ESCs) usually results in single cell lineage and could not form liver tissues. In this study, we examine the roles of epithelial cadherin (E-cad) in regulating ESC differentiation into liver tissue in vitro.

Methods E-cad was transfected into mouse ESCs to enable its stable expression. Hepatic differentiation of ESC was then induced by some hepatic growth factors. ESC differentiation progress was examined by detecting pluripotency transcription factor Oct-4, epithelial-mesenchymal transition (EMT) markers and Wnt/Β-catenin signal. Hepatic and angiogenesis markers were determined, and the adhesion forces (AF) between the differentiated cells were also examined.

Results E-cad expression gradually decreased in normal ESC (N-ESC) differentiation, but was more stable in E-cad-ESC (EC-ESC) group. In EC-ESC differentiation, Oct-4 and EMT markers expressions were prolonged, and cytoplastic Β-catenin level was much lower than that in N-ESC group. Hepatic markers expressions were earlier or higher in EC-ESC differentiation than that in N-ESC group. Angiogenesis markers VEGFR-1 and CD31/PECAM-1 expression only in day5-13 in N-ESC differentiation, whereas they maintained till on day17 in EC-ESC group. Finally, EC-ESC differentiation maintained multilayer-growth patterns, and many vascular network structures appeared and were migrated in ALB-positive cell areas. The AF of above structure was similar with that of mouse liver tissue.

Conclusion E-cad may act in synergy with hepatic growth factors to facilitate the early stage formation of hepatic tissues through regulating ESC differentiation progress by down-regulating EMT and Wnt/Β-catenin pathway. Rapid decrease of E-cad expression in normal ESC differentiation may at least partially contribute to the failure of tissue formation in vitro. The results of this study may also lead to the development of bioartificial liver systems and drug-metabo-lism assays.

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