Liquid crystals — the substance used in electronic displays — also can be used to monitor stem cell differentiation. Researchers at the University of Wisconsin-Madison have devised a liquid crystal-based cell culture system that may aid stem cell research. Often, cells grown in the laboratory differentiate in an uncontrolled way, resulting in cells that are of little use in medical research. The liquid crystal cell culture system offers a promising alternative to other monitoring techniques. The researchers placed gold specimen grids on glass slides and dispensed pressure-sensitive liquid crystals onto each grid. They added a fluorescently labeled solution of a material that produces an extracellular matrix upon which cells can be cultured. Human embryonic stem cells were grown at the interface of the crystals and the matrix and observed with phase-contrast imaging. As reported in the March issue of Advanced Functional Materials, the scientists found that the orientation of the liquid crystals was coupled to the presence and organization of the matrix material. The differentiated cells exerted pressure on the matrix and reorganized it, which caused changes in the orientational order of the liquid crystals. The subtle changes in liquid crystal texture and color caused by reorganization of the matrix could be visualized with fluorescence and polarized microscopy (in transmission mode, with white light), providing a simple tool for monitoring cell differentiation.