Dynamic expression of E-cadherin in embryonic stem cell differentiation in vitro and correlation with cell adhesion

BACKGROUND: E-cadherin plays an important role in development of liver tissue in the embryonic stage. Therefore, it is importance for investigating the feasibility of dynamic expression of E-cadherin in embryonic stem cell differentiation to in vitro development of liver tissue. OBJECTIVE: To observe the dynamic expression of E-cadherin in embryonic stem cell differentiation and the effect on cell adhesion. DESIGN, TIME AND SETTING: An in vitro cytological observation was performed at Surgical Laboratory of the First Affiliated Hospital of Sun Yat-sen University from December 2007 to December 2008. MATERIALS: Embryonic stem cells of BALB/c mice were obtained from Professor Huang (Department of Ophthalmology, Sun Yat-sen University). Twenty 13-day-old pregnant BALB/c mice of clean grade were provided by the Experimental Animal Center of Sun Yat-sen University. METHODS: Following trypsinization, embryonic stem cells were suspend-incubated in DMEM culture medium containing fetal bovine serum, 2-mercaptoethanol, HEPES, penicillin, and streptomycin. Embryoid body was formed 5 days after normal development and incubated in the culture plate at day 6. Liver tissue which was obtained from 13-day-old pregnant BALB/c mice was prepared for fetal liver cells which were frozen-sectioned as the controls. MAIN OUTCOME MEASURES: E-cadherin expression was detected using reverse transcriptase-polymerase chain reaction (RT-PCR) and immunocytochemistry at varying time points of 1, 5, 9, 13, and 17 days in stages of initial differentiation of embryonic stem cells, formation of embryoid body, and formation of differentiated clusters. Additionally, the effect of E-cadherin expression on cell adhesion was also detected. RESULTS: RT-PCR showed that E-cadherin mRNA expression was not observed at day 1 but peaked at day 5; gradually, the expression was decreased until the expression was stopped at day 17. E-cadherin mRNA expression was strong in fetal liver cells in the control group. Immunocytochemistry showed a similar outcome. Morphologically, embryonic stem cells developed from unicells into compact three-embryonic layer embryoid body and into incompact cell population. CONCLUSION: E-cadherin expression correlates with differentiated cell adhesion; additionally, the lost expression in an in vitro environment may be an important cause for unable regularization of differentiated cells.