A Kyoto University research team led by Associate Professor Kenji Osafune at CiRA has used a high-throughput compound screening system to identify substances that promote highly efficient differentiation of human iPS cells into intermediate mesoderm, from which the cells of the kidney, reproductive glands, and adrenal cortex originate.

As almost all kidney cells arise through differentiation from intermediate mesoderm, the essential step toward kidney regeneration is to develop technology for efficient differentiation of intermediate mesoderm from human iPS cells. By establishing a technology that performs efficient homologous gene recombination in human iPS/ES cells, the research team succeeded in introducing green fluorescent protein (GFP) into Odd-skipped related 1 (OSR1), which is a marker gene of intermediate mesoderm differentiation in human iPS cells, thus creating a system in which fluorescence can be used to confirm that cells have differentiated into intermediate mesoderm.

Using this system, the team searched for compounds that would induce highly efficient differentiation of iPS/ES cells into intermediate mesoderm and discovered two effective substances, the retinoids AM580 and TTNPB. This discovery should lead to the development of a reliable system for inducing differentiation of iPS/ES cells into kidney cells which will reduce cost compared to the conventional method using growth factors.

In the present research, a robotic system was used to screen a vast number of compounds for those which would be effective in inducing differentiation into intermediate mesoderm. Techniques using a robotic system of this kind have been widely used in drug discovery research.

Following the advent of iPS cells, attention is now focusing on the fact that they can also be used to research methods of inducing differentiation such as the present technique. Specifically, as growth factors and other proteins with human biological functions are high in cost and unstable as materials, they are not suitable for use on a large scale to induce differentiation. Going forward, it is expected that an important role will be played by a field known as chemical biology, in which cell status is controlled by low-molecular-weight compounds, which are lower in cost and materially more stable.

The research findings were published on January 15, 2014 (US Eastern time), in the online journal PLOS ONE.

Fig. Formation of renal tubule structures among cells derived from intermediate mesoderm

The cells which formed the tubular structures were positive for both LAMININ and LTL, suggesting that they were renal tubules.

Green: HuNu (i.e. human intermediate mesoderm-derived cells)

Red: LTL; Purple: LAMININ; Blue: nuclei; Scale bars: 100 µm.