A reminder that progress in the production of nanoscale scaffolds and surfaces is just as important as progress in biology in the stem cell field: "It's easy to give a stem cell a goal in life, apparently. Simply placing a cell in contact with a surface can provide sufficient information (a cue) to dictate how the cell will develop, and incredibly, even simple length-scale changes are enough to affect the outcome of the cell development. Far-fetched as this may sound, if you think about the nature of stem cells for a moment, it becomes less surprising that they are so responsive to their environment: how else to explain the extraordinary variety of cell types that derive from a uniform base material? As stem cells continue to be the focus of much research into the concepts of regenerative medicine and tissue engineering, a corollary challenge for materials science is the design and build for artificial substrates that can mimic biological environments and thereby control the growth and specialization of the cells. For one thing, the subtleties make it easy to grow off in the wrong direction. Growing muscle tissue will need a different set of conditions from, say, a new liver, but the differences in the environment might turn out to be very slight. A small change in the period of a pattern on the substrate might result in completely the wrong kind of tissue. A challenge of a more mechanical nature is the actual fabrication of the substrates. Most cell-growth environments have cues that act over a number of different length scales, with multiple patterns and features of various sizes interacting to produce the end result. Current micro- and nanofabrication techniques don't mimic this complexity too well, or rather, don't mimic it too well without complex multi-step procedures, expensive instrumentation, and expertise on fabrication that is not readily available to medical researchers."