Proliferation of hematopoietic stem cells differentiated from embryonic stem cells via sustained Wnt pathway activation / 中国组织工程研究

ABSTRACT

BACKGROUND:A variety of embryonic stem cells induction and differentiation systems have been established so far, while the research that promotes embryonic stem cells to differentiate into hematopoietic stem cells is stil at an initial stage, and the induction efficiency needs to be improved. OBJECTIVE:To active the Wnt/β-catenin signal pathway in mouse embryonic stem cells with exogenous win3a as an inducer, and then to observe whether the activation of this pathway wil promote the directional differentiation of embryonic stem cells into hematopoietic progenitor cells. METHODS:The ES-E14TG2a mouse stem cells were cultured with the exogenous wnt3a (100 μg/L) for 21 days, the content ofβ-catenin was tested by cellimmunofluorescence and western blot, and expression of Wnt downstream target gene was detected by quantitative reverse transcription PCR to determine the activation of Wnt/β-catenin signal pathway. Single-layer adherent culture method was used to induce the directional differentiate of above-mentioned cells into hematopoietic stem cells, and detection of hematopoietic development associated surface marker CD34+/Sca-1+was achieved by flow cytometry;meanwhile, the expression of hematopoietic associated gene was measured by quantitative reverse transcription PCR. RESULTS AND CONCLUSION:We found thatβ-catenin accumulated in ES-E14TG2a mouse stem cells after cultured with wnt3a (100 μg/L) for 21 days;the expressions of Wnt downstream target genes such as Pitx2, Frizzled, Sox17 and Oct4 showed the different degrees in increase, meaning the activation of Wnt/β-catenin signal pathway. Furthermore, during the time that we used single-layer adherent culture method to induce hematopoietic stem cells, the CD34+/Sca-1+cells accounted for 20.2%of total cells at day 14, and control cells only accounted for 11.9%. Again, expression quantity of hematopoietic associated gene BMP4, FLK2 and CD34 increased while Smad5 was suppressed significantly. Our data suggest that sustaining action by wnt3a wil active Wnt/β-catenin signal pathway, and also promote the directional differentiation of ES-E14TG2a mouse stem cells into hematopoietic progenitor cells.