Time course observation of cross-sectional shape of iPS cell colony using ultrasound spectroscopic imaging

The colony morphology of induced pluripotent stem cells is deeply related to cell functions. However, three-dimensional information during the growing process remains unexplored. Here, we non-invasively investigate the change in the cross-sectional shape of the colony for a long period of time. We develop a scanning-acoustic-microscopy system to construct spectroscopic acoustic images of cells in culture and then evaluate their height distribution. The images show fringe patterns due to acoustic interference near the edge of the colony, from which the colony height is accurately determined even in the thinner region. The time-variation analysis reveals that the colony shape approaches a dome shape, and the colony grows maintaining the similarity of its cross-sectional shape, and this indicates an exquisite balance between cell migration and cell proliferation in the colony.