Bioprinted heterogenous multistructured biomaterial with localized functionalization for the repair of complex tissue

The inherent complexity of cell arrangements and the diversity of tissues in the human body should be considered during the development of biomaterials. The recent emergence of multi-head printing techniques opened the possibilities to create heterogeneous scaffolds to repair or replace parts of the human body. For instance, additive manufacturing could be used to produce heterogenous materials composed of soft and hard layers, mimicking the structure of the tooth, as in this case study. Today, the gold standard for tooth replacement poorly replicates its structure, and 3D printing can better mimic its structure, allowing cell recolonization and helping tissue repair. We used a homemade dual head extruder 3D printer to print two different inks made of silk polymers. The first one was combined with ceramic microparticles to create a shell, while the second one was a foam-like scaffold to form the soft core of the scaffold, recreating the core/shell architecture of a tooth. The materials demonstrated a good biocompatibility and bioactivity with fibroblasts and Dental Pulp Stem Cells which were able to proliferate within the structures. The functionalization of the foam with an antibacterial agent was successfully performed. This study shows that a multi-head 3D printer can be used to create complex tissues with a heterogenous structure, in this case a non-cellularized shell surrounding a foam core cellularized with pulp stem cells. It opens the way for alternatives to a full tissue replacement by creating a patient-specific, biomimetic implant.