Disparity of stem cell-like characteristics among human amniotic epithelial cells in different areas

Objective To determine the disparity of stem cell-like characteristics among human amniotic epithelial cells(hAEC) in different areas of human amnion epithelium.Methods Amnion epithelium was digested by two steps to separate into basal hAECs and superficial hAECs.Expression of surface antigens and molecule markers Nanog,Oct4,Sox2,SSEA1,SSEA3,SSEA4,TRA1-60,TRA1-81 and CD73 in fresh isolated cells were detected by flow cytometer,immune-fluorescence and immunehistochemistry,and expression of SSEA3,TRA1-60 and TRA1-81 in human term full-thickness amnion and epithelium-separated human amnion after trypsinization were determined by histological stain method.Results The hAECs in basal area expressed stem cell markers Nanog,Oct4,Sox2,SSEA3,SSEA4,TRA1-60 and TRA1-81 at a higher level than those in superficial area.The hAECs intensely expressing SSEA4 are the smaller and roundish cells distributed mostly in the basal layer of amnion epithelium.Conclusion The basal hAECs have more embryonic stem cell(ESC)-like characteristics than the superficial ones.The basal area of human amnion epithelium may be the most important zone of reservation of human amniotic epithelial stem cells.