Cilia-Mediated Signalling in the Embryonic Nodes: A Computational Fluid-Structure-Protein Interaction (FSPI) Model

The breaking of left-right symmetry in the mammalian embryo is believed to occur in a transient embryonic structure, the node, when cilia create a leftward flow of liquid. It has been widely confirmed that this nodal flow is the first sign of left-right differentiation; however, the mechanism through which embryonic cilia produce their movement and how the leftward flow confers laterality are still requiring investigation. The ciliary motility in the embryonic node involves complex dynein activations and the handed information is transmitted to the cells by the flow produced by cilia, either mechanically and/or by advection of a chemical species. In this paper, we present a computational model of ciliary ultrastructure (protein-structure model) and discuss the scenarios that incorporate this internal microtubule-dynein system with the external fluidic environment (fluid-structure-protein interaction model, FSPI). By employing computational fluid dynamics, deformable mesh computational techniques and fluid-structure interaction analysis, and solving the three-dimensional unsteady transport equations, the protein-triggered mechanism of nodal ciliary motility has been studied, which is a primary component for the FSPI model. Future work regarding the integrative model is discussed, that will provide more accurate quantitative information on the flow rate, ciliary motion, and molecule/particle transport in the embryonic node and support the plausibility of hypotheses regarding left-right information transmission.