3D bioprinting of tissue constructs employing dual crosslinking of decellularized extracellular matrix hydrogel.

Bioprinted tissues are currently being utilized for drug and cosmetic screening mostly, but the long-term goal is to achieve human scale functional tissues and organs for transplantation. Hence, recapitulating the multiscale architecture, 3D structures, and complexity of native tissues is the key to produce bioengineered tissues/organs. Decellularized extracellular matrix (dECM)-based biomaterials are widely being used as bioinks for 3D bioprinting for tissue engineering applications. Their potential to provide excellent biocompatibility for the cells drove researchers to use them extensively. However, the decellularization process involves many detergents and enzymes which may contribute to their loss of mechanical properties. Moreover, thermal gelation of dECM-based hydrogels is typically slow which affects the shape fidelity, printability, and physical properties while printing complex structures with 3D printing. But, thermally gelled dECM hydrogels provide excellent cell viability and functionality. To overcome this, a novel dual crosslinking of unmodified dECM has been proposed in this study to render shape fidelity and enhance cell viability and functionality. The dECM-based bioink can be initially polymerized superficially on exposure to light to achieve immediate stability and can attain further stability upon thermal gelation. This dual crosslinking mechanism can maintain the microenvironment of the structure, hence allowing the printing of stable flexible structures. Optimized concentrations of novel photo crosslinkers have been determined and printing of a few complex-shaped anatomical structures has been demonstrated. This approach of fabricating complex scaffolds employing dual crosslinking can be used for the bioprinting of different complex tissue structures with tissue-specific dECM based bioinks.