Optical flow of vesicles: computer vision approach for endocytosis of nanoparticles in a living cell

The movement of vesicle in a living cell includes essential information for understanding the details of the intracellular transport. Although the vesicle tracking method has allowed us to understand precise movement of a single nanoparticle from the physical point of view, the whole cell-level transport has still not been clearly explained with the analysis of only a few representative vesicle movements. In this study, as an initial attempt to gain insight into cell-level vesicle transport, we adopted a computer vision technique to analyze the overall intracellular vesicle transport. In detail, we propose an algorithm to estimate and visualize the ow of the entire endocytic vesicles in terms of convergence and divergence with respect to the geometric cell center. In this algorithm, optical ow of the fluorescent nanoparticles in a living cell is computed using Lucas-Kanade method. Then, the direction of vesicle movement regarding the geometric center of the cell is calculated and mapped to visualize either converging or diverging movement, based on four-quadrant inverse tangent. With this suggested method, it is expected that we can gain insight into cell-level vesicle transport, which can help design and quantitatively evaluate various biomedical applications, including drug delivery.