Bioprinting of 3D cell-laden constructs with well-defined architectures and controlled spatial distribution of cells is gaining importance in the field of Tissue Engineering. New 3D tissue models are being developed to study the complex cellular interactions that take place during both tissue development and in the regeneration of damaged and/or diseased tissues. Despite advances in 3D printing technologies, suitable hydrogels or 'bioinks' with enhanced printability and cell viability are lacking. Here we report a study on the 3D bioprinting of a novel group of self-assembling peptide-based hydrogels. Our results demonstrate the ability of the system to print well-defined 3D cell laden constructs with variable stiffness and improved structural integrity, whilst providing a cell-friendly extracellular matrix "like" microenvironment. Biological assays reveal that mammary epithelial cells remain viable after 7 days of in vitro culture, independent of the hydrogel stiffness.

International audienceInternal erosion (IE) affects the stability of natural and reinforced materials by causing instability within their granular structure. The dislodgement and transport of eroded particles affect both the particulate concentration of eroding fluid and the pore network of eroded material. In this study, we examined these modifications using a transport model with a finite element code. First, IE tests on chemically reinforced sand columns were performed to obtain information about eroded material loss of mass, particulate concentration of effluent, porosity and permeability modifications, and existing IE stages. Second, based on experimental results, a mathematical one-dimensional model has been formulated to monitor the evolution and spatial distribution of erodible solids, fluidized particles, porosity, permeability, and seepage stresses. The model consists of a set of coupled nonlinear differential equations solved in sequence. It provides valuable information about the extent and the dynamics of structural changes, which can be used to estimate an IE time for the hydraulic work to reach failure