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.
ABSTRACT
Objective:To remove murine embryonic stem cells(mESC)from the differentiating cell culture and purify the differentiated cells by Magnetic Activated Cell Sorting(MACS).Methods:Neural differentiation of mESC was induced by a 5-stage method.The specific cell surface marker,SSEA-1,was used to identify ES cells in the differentiating cells.The optimal dilutions of mouse anti mouse SSEA-1 IgM primary antibody and FITC conjugated goat anti mouse secondary antibody were determined before the flow cytometry test.The incubation time and incubation temperature of primary antibody were all optimized to make the cytometry test accurate.After the optimization,stage 4 cells were dissociated into single cell suspension,incubated with antibody of SSEA-1 and microbeads conjugated goat anti mouse IgM,and then sorted through the magnetic field.The rate of SSEA-1 positive cells in pre-and post-separation groups was assessed by flow cytometry,and the viability of cells was evaluated by trypan blue staining counting under light microscopy.Results:The proportion of SSEA-1 positive cells in the separated cells can be reduced from(7.19?1.36)% to(1.34?0.80)%.The survival rate of sorted cells was more than 92%,similar to that of pre-separation cells.Conclusions:The MACS system we used can effectively remove mESC from the differentiated cells.The sorted cells will be well provided for the subsequent studies about transplantation therapy.
ABSTRACT
Objective To culture human embryonic germ cells in vitro and identify them by observing the expression of the surface markers SSEA-1 and Oct-4. Methods The gonadal ridges and mesenteries of human embryos at 5～9 weeks post-fertilization were isolated and then cultured in vitro.Flow cytometry and immunocytochemistry were applied to detect whether the cells cultured express SSEA-1 and Oct-4.Immunohistochemistry was also carried out to observe the expression of SSEA-1 on the PGCs which locate in the gonadal ridge. Results Both the cells and the cellular colonies cultured in vitro expressed SSEA-1 and Oct-4.The immunohistology study of gonadal ridges also showed that there were many PGCs which were SSEA-1 positive in it.Conclusion The cells we obtained through tissue culturing are undifferentiated human embryonic germ cells,which originate from hPGCs.