Fragmentation and size control in collectively migrating strands

In many developmental processes, cells often fragment into clusters during collective migration under confinement, such as the formation of small metastatic clusters in cancer metastasis. What factors control the sizes and rupture rates of these clusters? Building on our previous work modeling strands of cells invading into new regions, we study this question by using a simple active Brownian particle chain model. Our results suggest that a stable cluster size distribution can be achieved by incorporating cell division and imposing a minimum cluster size. Additionally, introducing leader cells at the ends of the chain or implementing a velocity-alignment mechanism modifies the correlation length of cell polarity along the chain, which significantly alters the break rate of cell-cell junctions within the chain, leading to changes in cluster size distribution.