Determining material properties of the embryonic chick heart during cardiac looping morphogenesis

Cardiac looping is a fundamental developmental process that is the first morphogenetic sign of lateral (left-right) asymmetry in the vertebrate embryo. The biophysical mechanism that drives the early linear heart tube to bend and rotate dextrally (rightward) into a c-shaped loop is still unknown, although several genetic and epigenetic factors have been implicated. There have been some theoretical mechanical models of looping. What has been lacking in models of looping are appropriate material properties for the tissue. Our lab has developed a poking device ("heart poker"), which not only gives force-deformation (i.e. stiffness) data, but also allows us to analyze the shape of indentation and input that information into a finite element (FE) model to determine material properties. A simulated annealing (SA) algorithm is used to optimize the agreement between the experimental and model results.