Mechanical Evidence of the impossibility of directed motion of Trypanosoma cruzi towards preferred organs in the Human Body, a simulation 2D model within a laminar flow

Abstract

The movement of the infective form of the T. Cruzi parasite within the human blood is not completely understood. Video microscopy observations confirm forward motility of the protozoa and relate it to the deformation of the body, nonetheless there are open questions relating the deformation of the protozoan with its motion in blood, for which a computational model would be very helpful. Hereby we introduce a simple computational 2D model to test whether it is mechanistically possible for the parasite to direct its movement through the blood stream towards preferred organs in the bloodstream. We model the infective form of the T. cruzi, the causative agent of Chagas disease; by means of a network of harmonic springs that represents its body, without explicitly modeling the flagellum. We coupled this with a particle model of a laminar fluid flow, which we implemented using the Dissipative Particles Dynamics method. Our parasite model swims on still fluid, its center of mass displacement being larger than the end to end deformation. Laminar flow dragged the model parasite of the order of 5 $μm$; having minor effects on its structure. The parasite model does not exhibit directed motion in a moving fluid, suggesting that the large-scale displacement of the real parasite is not attributable to its own motility but is instead caused by it being dragged by the flow. We highlight two potential improvements for the model: incorporating the capacity to describe 3D motion and including a specific depiction of the flagellum.