An open system of migrating cells, continuously supplied with new cellular material, spontaneously develops chiral multi-armed spirals. The finding describes a self-organization pattern that arises when a constant flow of cells prevents the system from reaching a static state and keeps it in a dynamic, out-of-equilibrium regime.

The work addresses an open question in systems biology: how ordered structures with a defined chirality emerge in cell populations that grow and renew continuously. Most patterns previously described in cell cultures corresponded to stationary configurations or to collective migration phases without persistent spiral structure. The appearance of multiple arms with a preferred sense of rotation adds a level of geometric order not previously documented under these conditions.

The key to the phenomenon lies in the open nature of the system: continuous cell supply compensates for the loss of material and keeps the assembly in an active, dissipative state. Under these conditions, the interplay between cell migration, proliferation and the global flow of material gives rise to an instability that organizes the population into spiral arms winding with a dominant chirality. The chirality, that is, the preference for one sense of rotation over the other, emerges from collective behaviour rather than from an individual property of each cell.

The relevance of the result lies in showing that continuous supply of components is an effective control to select and stabilize complex patterns in active biological systems. The same framework could apply to other living or active systems in which material renewal is relevant, and it offers a way to study how chiral symmetry is broken in growing tissues. It remains to be determined which specific parameters of cell flow and migration set the number of arms and the sense of rotation, and whether the same mechanism operates in three-dimensional tissues.