3D nichoid substrates affect mesenchymal stem cell morphology and euchromatin organization

In recent years, it has been demonstrated that the extracellular microenvironment plays a pivotal role in controlling mesenchymal stem cell fate and functionality. At the basis, there is the mechanotransduction process by which cells sense physical forces and translate them into biochemical/biological responses. In order to modulate gene expression, cell mechanotransduction involves cell-substrate interaction and cytoskeleton proteins, but also nuclear geometry and chromatin remodelling. We developed an innovative isotropic 3D culture substrate, nanoengineered via two-photon laser polymerization, able to control nuclear shape. In this work, we studied cell cytoskeleton and chromatin organization of rat bone marrow mesenchymal stem cells seeded into our 3D scaffold and compared to cells grown on standard flat glass substrates. Our results show that the 3D micro-lattice structure inhibits the formation of actin cup and fibers joining cell periphery to the nucleus. It affects nuclear morphology and euchromatin organization. Interesting, similar results were obtained on cells treated with a drug able to inhibit actin polymerization and cytoskeleton organization. In order to correlate euchromatin localization and organization with cell fate and functionality, future work will be focalized investigating gene expression of MSC cultured on standard glass 2D substrate and into our 3D micro-lattice structure.