Decellularized cartilage tissue bioink formulation for osteochondral graft development.

Abstract

Articular cartilage and osteochondral defect repair and regeneration presents significant challenges to the field of tissue engineering (TE). TE and regenerative medicine strategies utilizing natural and synthetic-based engineered scaffolds have shown potential for repair, however, they face limitations in replicating the intricate native microenvironment and structure to achieve optimal regenerative capacity and functional recovery. Herein, we report the development of a cartilage extracellular matrix (ECM) as a printable biomaterial for tissue regeneration. The biomaterial was prepared through decellularization and solubilization of articular cartilage. The effects of two different viscoelastic modifiers, xanthan gum and Laponite®, and the introduction of a secondary photo-crosslinkable component on the rheological behavior and stability were studied. The rheological evaluation of the bioinks demonstrated the tunability of the bioinks in terms of their viscosity and degree of shear thinning, allowing the formulations to be readily extruded during 3D printing. dcECM-Laponite® bioink formulations demonstrated rheological property G' ranging from 750 to 4000 Pa, which is three orders of magnitude higher than that for the dcECM-XG bioink formulations. Furthermore, this was further increased to G' ranging from 2400 to 5700Pa post-crosslinking. Herein, a spreadable ink composition was identified to form a uniform cartilage layer post-printing. The choice of viscosity modifier along with UV cross-linking warrants shape fidelity of the structure post-printing, along with improvements in the storage and loss moduli. The modified ECM-based bioink also significantly improved the stability and allowed for prolonged and sustained release of loaded growth factors through the addition of Laponite®. The ECM-based bioink supported human bone-marrow derived stromal cell and chondrocyte viability and increased chondrogenic differentiation in vitro. By forming decellularized cartilage ECM biomaterials in a printable and stable bioink form, we develop a "Cartilage Ink" that can support cartilaginous tissue formation by closely resembling the native cartilage extracellular matrix in structure and function.