Abstract: An object of the present invention is to provide a method of promoting polyploidization of megakaryocytes and thereby producing highly polyploidized megakaryocytes, a method of efficiently producing platelets from polyploidized megakaryocytes, and the like. The present invention provides a method of producing polyploidized megakaryocytes comprising a step of forcing expression of an apoptosis suppressor gene in megakaryocytes before polyploidization and culturing the resulting cells.

Abstract: A method for efficiently preparing blood cells, such as mature megakaryocytes and platelets, from iPS cells is achieved in an in vitro culture system. A sac-like structure encloses hematopoietic progenitor cells, which is obtained by inoculating iPS cells onto feeder cells and then culturing the iPS cells under conditions suitable for inducing the differentiation of hematopoietic progenitor cells. Moreover, a method for producing various types of blood cells, comprises culturing hematopoietic progenitor cells enclosed in the sac-like structure under conditions suitable for inducing the differentiation of blood cells. Furthermore, a method for producing various types of blood cells, particularly megakaryocytes and platelets, is achieved without involving the sac-like structure.

Abstract: It is an object of the present invention to provide a method for efficient differentiation into blood cells. Specifically, in the present invention, when blood cells are produced from pluripotent stem cells such as ES cells or iPS cells in vitro, the cells are cultured under a low oxygen partial pressure to increase the efficiency of differentiating the pluripotent stem cells into hematopoietic progenitor cells, erythroid progenitor cells, and the like, so as to increase the number of finally obtained, desired blood cells.

Abstract: The present invention has an object of providing a method for producing specific cells by amplifying cells in a desired differentiation stage. The present invention provides a method for producing specific cells by inducing differentiation of cells, wherein an oncogene is forcibly expressed in cells in a desired differentiation stage to amplify the cells in the desired differentiation stage. The present invention also provides a method for producing specific cells, wherein oncogene-induced senescence (OIS) which is induced by the oncogene expressed in the cells in the desired differentiation stage is suppressed.

Abstract: An object of the present invention is to provide a sac-like structure enclosing hematopoietic progenitor cells and a method for preparing the sac-like structure as well as a method for efficiently preparing blood cells such as mature megakaryocytes and platelets from the sac-like structure. The present invention provides a sac-like structure enclosing hematopoietic progenitor cells, the sac-like structure being obtained by plating ES cells onto feeder cells and culturing the ES cells under suitable conditions for inducing hematopoietic progenitor cell differentiation. Moreover, the present invention provides a method for producing various blood cells, the method comprising further culturing hematopoietic progenitor cells enclosed in the sac-like structure under suitable conditions for inducing blood cell differentiation.

Abstract: It is an object of the present invention to provide a method for efficiently preparing blood cells, such as mature megakaryocytes and platelets, from iPS cells in an in vitro culture system. The present invention provides a sac-like structure enclosing hematopoietic progenitor cells, which is obtained by inoculating iPS cells onto feeder cells and then culturing the iPS cells under conditions suitable for inducing the differentiation of hematopoietic progenitor cells. Moreover, the present invention also provides a method for producing various types of blood cells, which comprises culturing hematopoietic progenitor cells enclosed in the sac-like structure under conditions suitable for inducing the differentiation of blood cells. Furthermore, the present invention also provides a method for producing various types of blood cells, particularly megakaryocytes and platelets, without involving the sac-like structure.

Abstract: An object of the present invention is to provide a sac-like structure enclosing hematopoietic progenitor cells and a method for preparing the sac-like structure as well as a method for efficiently preparing blood cells such as mature megakaryocytes and platelets from the sac-like structure. The present invention provides a sac-like structure enclosing hematopoietic progenitor cells, the sac-like structure being obtained by plating ES cells onto feeder cells and culturing the ES cells under suitable conditions for inducing hematopoietic progenitor cell differentiation. Moreover, the present invention provides a method for producing various blood cells, the method comprising further culturing hematopoietic progenitor cells enclosed in the sac-like structure under suitable conditions for inducing blood cell differentiation.