2D protein arrays induce 3D in vivo-like assemblies of cells.

We report on the ability of two-dimensional protein crystals to induce the formation of homo- and heterotypic multicellular spheroids (MCSs) which resemble the morphology and hierarchical organization of living tissues and tumours. We have systematically studied the influence of the initial cell density and incubation time on the kinetics of spheroid growth and spheroid lifespan. Hereby a novel methodology has been established to produce MCSs on protein-based molecular layers.