Establishment of feeder layer-and serum-free culture system of human embryonic stem cells / 中国组织工程研究

ABSTRACT

BACKGROUND:FGF2,TGFβ/activin/nodal and IGF signal pathways are necessary for keeping functions of human embryonic stem calls,but there was no report concerning whether addition of exogenous basic fibroblast growth factor,transforming growth factor β and insulin can maintain self-renewal of human embryonic stern cells.OBJECTIVE:To establish a feeder layer-and serum-free culture system of human embryonic stem cells.DESIGN,TIME AND SETTING:The cytological in vitro study was performed at the Kunming Animal Institute of Chinese Academy of Sciences from September 2007 to February 2009.MATERIALSPregnancy 12.5 or 13.5-day ICR strain mica (clean grade) were provided by the Animal Center of Kunming Medical College.Human embryonic stem cell line BG02 was purchased from Bresagen,USA.METHODS:BG02 cells were digested,centrifuged,resuspended in feeder layer-free medium,and then incubated for 5-7 days.Differentiated human embryonic stem cells were removed.Dispase was added for digestion.Samples were cut into blocks,centrifuged,resuspended,and then incubated at 13 in a 4-well plate coated with laminin in feeder layer-free and serum-free medium,supplemented with 80% DMEM/F12,20% KSR,2 mmol/L glutamine,1% non-essential amino acid,0.1 mmol/L β-mercaptoethanol,insulin-transferrin-selenium (ITS) (×1),10~6 U/L penicillin,100 mg/L streptomycin,4 μg/L basic fibroblast growth factor (bFGF) and 0.12 μg/L transforming growth factor-β1 (TGF-β1).ICR fetus mica were sterilely obtained to culture mouse embryonic flbroblasts by tissue pancreatin digestion method.These cells were incubated in a 6-well plate coated with 0.1% gelatin.Human embryonic stem cell line BG02 cultured on mouse embryonic fibroblasts feeder layers was transferred to laminin-coated plates in serum-free medium containing bFGF,TGFβ1 and ITS.MAIN OUTCOME MEASURES:The morphology of BG02 cells in feeder layer-and serum-free condition was observed.The specific molecular markers of human embryonic stem cells were determined by immunohistochemical staining.The karyotype and differentiation ability in vitro of BG02 cells were analyzed.The differences in the proliferation and the differentiated rate of BG02 clumps in feeder layer-and serum-free condition or mouse embryonic fibroblast feeder layer condition were compared.RESULTS:BG02 calls had been continuously cultured for at least 20 passages in feeder layer-and serum-free culture condition.BG02 clones in this culture system had typical human embryonic stem cell morphology.BG02 cells all expressed SSEA-4,SSEA-3,TRA-1-60,TRA-1-81,Oct-4,but did not express SSEA-1.After 20 days of culture,BG02 cells had the capacity to differentiate into derivatives of embryonic endoderm,mesoderm,and ectoderm.Differentiated cells could express alpha-fetoprotein,nestin,α-actin.At passage 20,call karyotype was normal (46XY).The growth of BG02 cells cultured in feeder layer-and serum-free condition was more slowly compared with mouse embryonic fibroblast feeder,and doubling time was significantly prolonged (P ＜ 0.05).Differentiation rate of the colonies was significantly increased (P ＜ 0.05).CONCLUSION:A feeder layer-and serum-free condition for culture of BG02 cells has been established.The addition of bFGF,TGFβ1 and ITS can maintain the self-renewal of BG02 cells.