Synchronized Dual Bioprinting of Bioinks and Biomaterial Inks as a Translational Strategy for Cartilage Tissue Engineering

In this study, we propose a novel synchronized dual bioprinting approach that combines two distinct printing strategies for mechanically and biologically improved substitutes for cartilage tissue engineering. Mechanical stability is achieved using a biomaterial ink (polysaccharide based) for microextrusion printing, whereas the cell-loaded functional bioink (type I collagen based) is bioprinted using cell compatible drop-on-demand (DoD) bioprinting. After an exploratory preselection of bioinks with printability and biocompatible characteristics, articular cartilage substitutes have been dually bioprinted using human knee articular chondrocytes (hKACs) from four independent donors. Our findings showed that dual bioprinting improves the compressive modulus from about 20 kPa (only bioink) to up to 600 kPa (bioink plus biomaterial ink). In addition, the biomaterial ink was found to be well interconnected with the bioink, which is important for future translational research. Chondrogenesis of hKACs was possible in functional bioinks with intermediate collagen concentration among the studied blends and satisfactory printability characteristics. We conclude that dual bioprinting is a promising and advanced strategy for cartilage tissue engineering.