I am a chargé de recherche at Institut Curie, and my research focuses on understanding how the interplay between active processes and topological defects drive shape changes in soft materials. Gaining a deeper understanding of these mechanisms can provide insights into the morphogenesis of biological tissues and inform the design of shape-morphing materials.

Abstract:

Gliomas organize as nematic liquid crystals: three-dimensional nematic order, disclinations and quasi-long-range order

Anisotropic cells can exhibit both orientational order and topological defects, each of which influences their collective behavior. In the first part of this talk, I will discuss conditions under which glioblastomas (GBMs) organize as nematic liquid crystals. By analyzing 3D reconstructions of H&E-stained sections, as well as images of optically cleared gliomas, we establish the existence of three-dimensional nematic order and disclinations in both mouse and human glioma brain tumors in vivo. Two-dimensional sections through these disclinations appear as ±1/2 topological defects. In 3D, these defects either persist along disclination lines or twist as they interconvert from −1/2 to +1/2. Cell alignment exhibits quasi–long-range order, extending throughout the tumor over distances ranging from 300 to 3000 µm. This large-scale order correlates with the tumors’ aggressive behavior. The organization of gliomas as nematic liquid crystals offers a novel physical framework for understanding complex solid tumors. In the second part of this talk, I will discuss how adding colloidal particles may modify the bulk properties of GBMs. Then, I will present a theoretical study in which we investigated how a suspension of particles in a passive liquid crystal alters its bulk properties. In particular, we derived explicit formulas for the effective viscosity of the resulting composite medium.