A research group led by Tatsutoshi Nakahata, a professor at the Center for iPS Cell Research and Application (CiRA), Kyoto University, and Megumu Saito, a lecturer at CiRA, has reported a highly efficient and reproducible method for producing hematopoietic cells from human ES cells^{(Note 1)} and iPS cells^{(Note 2)} with serum^{(Note 3)}–free medium, which contains no animal-derived elements, via mesodermal^{(Note 4)}progenitor cells. The study was conducted in collaboration with Toshio Heike of the Department of Pediatrics at the university.

Aiming at the creation of various blood cells such as neutrophil cells and red blood cells, the research team cultured human ES/iPS cells with serum-free medium, and changed the concentration of cytokine^{(Note 5)}and the timing of its delivery. They succeeded in generating a variety of blood cells after inducing ES/iPS cells in the same step-by-step manner as the process of human embryo development. The newly established method to induce the blood cells is more efficient and reproducible, compared to other protocols. It is hoped that this method will accelerate research towards disease analysis and medical application.

This research was conducted in collaboration with Kyoto University's Department of Pediatrics and Institute for Frontier Medical Sciences, and WASEDA Bioscience Research Institute in Singapore. Its result appeared in the July 27 issue of Plos ONE, an American science journal.


Title of the paper:
"A novel serum-free monolayer culture for orderly hematopoietic differentiation of human pluripotent cells via mesodermal progenitors"

Authors:
Akira Niwa, Toshio Heike, Katsutsugu Umeda, Koichi Oshima, Itaru Kato, Hiromi Sakai, Hirofumi Suemori, Tatsutoshi Nakahata, and Megumu K. Saito

• PLoS ONE's web site

Note 1: ES cell
Embryonic stem cell (ES cell) is a kind of pluripotent stem cells which have the capacity of turning into any kind of tissues. ES cells can be obtained by taking the inner cell mass of the blastocyst that develop into functional cells and then culturing them. Human ES cells were established in 1997 for the first time in the world.

Note 2: iPS cell
Induced pluripotent stem cells (iPS cells) are created by introducing a few factors into somatic cells such as skin cells. They have the similar properties of infinitely growing and of differentiating into any type of cells in the body as ES cells do. The first establishment of mouse iPS cells was reported in 2006, and the first generation of human iPS cells was announced in 2007.

Note 3: Blood serum
Serum is upper clear liquid part of blood after coagulation. In culturing cells, fetal bovine serum is often added as an auxiliary reagent to help cells grow. Serum, however, contains various unknown components, which leads to unstable results of experiments.

Note 4: Mesoderm
In the early animal embryo, a mass of undifferentiated cells gradually separate into three layers: ectoderm, mesoderm, and endoderm. Mesoderm develops into blood, cardiac muscle, blood vessel, kidney, etc.

Note 5: Cytokine
Cytokine is a kind of proteins secreted from a variety of cells and influences specific functions of cells. A variety of cytokines are mass-manufactured and used in research and clinical practice.