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Embryonic stem cells are derived from the inner cell mass or primordial germ cells of mammalian embryos, such as human, murine and non-hunman primates. These cells are totipotent cells which have capable of unlimited, undifferentiated proliferaton in vitro.There have been many reports on induction embryonic stem cells into various kinds of cells-including hematopoietic ,vascular endothelial, cardiac muscle, neuronal, pigment, pancreatic β-cells.Hematopoietic stem cells (HSC) transplantation is the most common cell-based therapy applied today. However, HSC from human bone marrow(BM),mobilized peripheral blood, and umbilical cord blood(CB) that represent the major source of transplantable cells for clinical therapy have limited availability as two-third of potential patients lack well-matched donors .Embryonic stem cells offer a unique tool to provide an alternative source of transplantable blood cells.There are current 2 widely used protocols to generate hematopoietic cells in culture. In the first protocol, ES cells differentiate and form 3 dimension cell masses called embryoid bodies (EBs).During the process, soluble growth factors and cytokine, such as BMP4, VEGF, IL3, IL6, G-CSF, M-CSF, EPO are often utilized. In the second protocol, ES cells differentiate on type Ⅳ collagen or stromal cells such as OP9. Although these two methods have great attribution on generation hematopoietic cells from ES cells. They also have some defects: ①OP9 stromal cells are derived from op~-/op~- murine, and it’s difficult to get humans’ OP9 cells. In future, on the research of human embryonic stem cells, it’s harmful to use murine OP9 cells to induce human embryonic stem cells to differentiate.②Using the mixture of different cytokines will increase the cost of the research greatly, and will make the clinical therapy too expensive, thus this method can’t accepted by most of patients.In this experiment, we use osteoblasts to induce ES cells to differentiate into HSC by coculture method. There have been many reports that osteoblasts are crucial components of particular niches for hematopoietic stem cells in adult bone marrow (BM). Osteoblasts have been demonstrated to generate a few cytokines which can
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