Instabilities in tissues and cell aggregates

Caption: Shape instability in a multicellular spheroid. The unperturbed shape is spherical (dashed circle). The color gradient denotes metabolite concentration. Dividing cells (red) are located close to the surface, dying cells (dashed) close to the center. Differential flows create viscous shear stresses that destabilize the spherical shape.

The shaping of tissues plays an important role during normal development as well as during abnormal tissue growth. If biochemical determinants control tissue faith, tissue growth also obeys the laws of physics, especially those of biomechanics. We currently are trying to determine in which circumstances the sole presence of cell divisions and cell deaths can trigger spontaneous shape instabilities. We have first shown that such phenomena can take place in multilayered epithelia, where fingering instabilities can exist. We have then shown that a similar phenomenon can take place in cellular aggregates, with an instability of the spherical shape.