Correlation between the amount of residual undifferentiated embryonic stem cells in embryoid bodies and its tumorigenicity / 国际生物医学工程杂志

ABSTRACT

Objective To explore the correlation between the amount of residual undifferentiated embryonic stem cells (ESCs) in embryoid bodies and its tumorigenicity.Methods Mouse R1 ESCs were cultured in suspension to form embryoid bodies (EBs).Ten days later,EBs were digested into single cells and then re-plated in standard ESCs culture condition.The residual undifferentiated embryonic stem cells surface maker SSEA-1 was examined by flow cytometry in EBs.The morphology of residual undifferentiated cells in EBs were observed,meanwhile the surface marker SSEA-1 was examined by immunofluorescent staining.EBs were digested into single cells and grouped into 104,105,106,2×106,and then injected into limb muscle of nude mice.The correlation of the amount of cells and its tumorigenicity was observed.Results Residual undifferentiated ESCs were observed after EBs differentiated for 10 days,which displayed clonal morphology and expressed undifferentiated ceil markers of ESCs,such as SSEA-1.The expression rate of undifferentiated cells surface marker SSEA-1 was (13.5±0.75)％ in EBs differentiated for 10 days.Only two millions single cells harvested from EBs were able to form teratoma after being injected into muscle of nude mice for 6 weeks.Mature endoderm,mesoderm and ectoderm tissues could be found in teratoma.No teratoma formed in other groups.Conclusion A certain amount residual undifferentiated ESCs still exist after differentiation of ESCs into EBs.About 2.7× 105 undifferentiated cells are able to form teratoma by iniecting into muscle of nude mice.