Using Atomic Force Microscopy to Characterize Local Material Environments in Developing Embryos

The cardiac development process of early stage chick embryos was investigated using contact mode atomic force microscopy (AFM). Within the early stages of embryo growth, the chick heart is structured as a C-shaped tube. As the embryo develops, the heart tube bends over itself forming an alpha shape that is necessary for further development. The consequences of this looping process, which also occurs in developing human embryos, are well understood but the forces that drive this mechanism require further examination. Failure for this heart looping to occur in humans can result in congenital heart defects and other cardiac issues. To investigate the driving forces of this action, the mechanical properties, such as stiffness and energy dissipation, of highly localized embryonic regions were investigated across multiple chick embryos that were incubated for 48-52 hours, referred to as stage 12. Specifically, microscale single-indentation curves were obtained using the AFM across an array of locations on the cranial region of the chick embryo. The primary focus of this experiment is to investigate the potential effect of the material properties of the embryo on the cardiac development process. The results of our experiments compare favorably to previously published data using a different micro indentation apparatus on similarly staged chick embryos. Our tests have obtained stiffness values ranging from 10 - 14 nN/µm and other tests have stiffness values ranging from 4 - 10 nN/ µm. Future tests will continue to probe material property values for stage 12 embryos as well as investigating later stages of embryonic growth. By investigating the material properties across various regions and stages of chick embryos, the exerted mechanical forces and the cardiac development process can be better understood.