(776e) Controlling Embryonic Cell Sheet Migration Using Microfluidics

Embryonic development consists of a complex series of cell signaling, cell migration and cell differentiation events whereas morphogenesis is the process that controls the organized spatiotemporal distributions of these events. Cell sheet migration is central to embryonic development, to homeostasis of complex organs, and to disease pathology therefore studying cell migration within sheets is important. Embryos from the African Claw-toed frog, Xenopus laevis, are used to elucidate genes important in moving cells. However, little is known about the underlying mechanism by which cells in epithelial sheets coordinate their responses to growth factors, directional signals, and motility cues to direct sheet movement in vivo. One reason for this knowledge gap is the lack of technologies to control of the chemical microenvironment surrounding multicellular tissues. Here, we manipulate the chemical microenvironment with precise spatiotemporal delivery of cytoskeletal inhibitors and contraction-stimulating compounds using laminar flow interfaces with microfluidics. We find that microfluidics can pattern cell responses and control cell motility of multicellular sheets and may allow engineers the ability to initiate and control the outcome of synthetic morphogenetic programs. We use this approach to study motility of the cells within the sheets to these localized environments and understand how their coordinated behavior works with spatiotemporal control.

Microfluidics provides an opportunity to control chemical stimulation of biological systems using laminar flow interfaces with well-known flow modulation methods. To deliver precise chemical stimulation to a multicellular tissue, we have developed a system for controlling the inlet pressures to a microfluidic device by modulating fluidic resistance and capacitance. We employed this system to deliver chemicals over tissue explants from Xenopus embryos with a spatiotemporal control to study mechanical patterning and local control of cell sheet migration during epibolic-type morphogenetic movements. This approach enabled spatiotemporally controlled inhibition of cell sheet migration in an embryonic tissue to investigate the dynamic responses to localized inputs.

We observed that applying blebbistatin (BBS), a myosin inhibitor, to half of the animal cap explant, we could affect cell migration. When we stimulated the animal cap explant locally with BBS locally with our microfluidic system in vivo, sheet migration altered during epibolic-type morphogenetic movements. Using time-lapse microscopy, we were able to observe localized response, analyze the dynamics with kymographs, and construct spatiotemporal strain maps. 

The development of new technologies to control the form of growing multicellular tissues advance the goals of regeneration and tissue engineering and produce new applications in bioengineering and medicine. We believe that patterning cell mechanics and controlling cell motility provide a means to initiate synthetic morphogenetic programs. In addition, the ability to control the form of multicellular tissues potentially has high impact in tissue engineering and regeneration applications in bioengineering and medicine.