EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Introduction 3D Bioprinting provides the ability to produce engineered tissues with desired macroscopic shapes, chemical and biological gradients. However, the field is still lacking methods to reproduce microscopic matrix architecture. In this study we introduce a technique to control distribution and orientation of fibrillar collagen (col) embedded within a hyaluronan (HA) bioink matrix via extrusion-based 3D printing. Cell-free and cell laden constructs were prepared studying the influence of this controlled microscopic anisotropy on cell behavior and chondrogenic differentiation.Materials and Methods Tyramine modified HA was mixed with col I from rat tail or col II from Jellyfish (JCol) at varying ratios. hMSC spheroids were embedded into biomaterials (5 Mio/ml), enzymatically crosslinked for 3D-bioprining or casting with subsequent light-crosslinking. Casted HA and hMSC pellets were prepared as control groups. Embedded hMSC were differentiated in chondrogenic media containing TGF-β1 for 21 days and analyzed for cartilage matrix synthesis (histology, proteoglycan quantification, PCR).
Results Col fibril formation was shown by fluorescence imaging resulting in anisotropic orientation after 3D-bioprinting. hMSCs migrated throughout HA-col, but not in HA and HA-JCol. hMSCs underwent chondrogenic differentiation in HA-col gels marked by proteoglycan production, which was not observed for HA. Upregulation col II (5017x), aggrecan (136x) and SOX9 (3.6x) confirmed MSCs differentiation towards chondrocyte lineage in HA-col, confirmed by limited upregulation of col-I (0.6x), RunX2 (1.4x) and col X (31.8x), which was more pronounced in pellet control compared to HA-col.
Conclusion A method to obtain a HA-col composite with macroscopic homogeneity and microscopic heterogeneity mimicking the macromolecular architecture of animal tissues was introduced. The possibility of printing matrix components with control over microscopic alignment brings biofabrication one step closer to capturing the complexity in animal tissues.