3D Bioprinting of human Mesenchymal Stem Cells in a novel tunic decellularized ECM bioink for Cartilage Tissue Engineering

Tunicates are marine organisms renowned for their thick, leathery exoskeleton called tunic. This tunic is composed of an extracellular matrix packed with protein-cellulose complexes and sulfated polysaccharides, making it a charming biomaterial choice for cartilage tissue engineering. In this study, P.nigra tunicate was collected and processed to obtain its rich decellularized extracellular matrix (dECM). The dECM was either seeded with human mesenchymal stem cells (hMSCs) as is or underwent further processing to form a hydrogel for 3D bioprinting. The characterization of tunic dECM was achieved by FTIR, XRD, TGA, Raman spectroscopy, SEM and tensile mechanical analysis. Biological compatibility and staining were done by live/dead, alamar blue, alcian blue, safranin O and PCR gene expression. After decellularization, the tunic dECM scaffold preserved the natural honeycomb-shaped microstructure, as well as its functional cellulose and protein groups. Both the tunic dECM scaffolds and bioprinted scaffolds showed enhanced metabolic activity, cell proliferation and chondrogenic differentiation. Combining both the mechanical robustness and biocompatibility, the bioink is able to fill the elusive gap in cartilage regeneration. This study offers a new potential source of dECM scaffolds and bioinks which are both biologically compatible and mechanically stable, making it a one stop shop for cartilage tissue engineering.