Microengineering The Neural Tube

Abstract

Early embryonic development is a complex and highly regulated orchestra of instructive cues that collectively guide naïve stem cells towards progressively more specialized fates. In the neural tube, the precursor structure to the brain and spinal cord, these signals emanate from ‘organizing centers’ surrounding the neural tube. These organizing centers send out soluble cues or morphogens that diffuse tens to hundreds of microns to recipient cells residing in the neural tube. Re-creating this dynamic landscape of cues in vitro is impossible using standard cell culture tools and techniques. However, microfluidics is perfectly suited to fill this gap, allowing precise control over the microenvironment on the same length scale as the developing embryo. A microfluidic device is presented that is able to re-create some of the spatial patterning events that occur during the early development of the neural tube. This platform enables developmental biologists to reverse engineer development from the ground up, enabling researchers to pose radically new experiments to help answer some of the most relevant questions regarding fate specification in the developing neural tube. Here the device is used to guide mouse embryonic stem cells into motor neurons. Importantly, these motor neurons are able to be directed to differentiate in a defined region of the microdevice, a spatial patterning event that is the hallmark of the developing neural tube. For the first time it is now possible to study the effect of development cues on live populations of stem cells. The characterization of these fundamental developmental processes will prove invaluable in understanding how humans acquire both form and function. One day, it may allow researchers to harness these developmental techniques, which have been refined over thousands of years of evolution, to guide patient derived cells into any user defined cell fate