Advances in biofabrication techniques towards functional bioprinted heterogeneous engineered tissues: A comprehensive review

Biofabrication is a fast-evolving and multi-disciplinary field, harnessing the benefits and capabilities of additive manufacturing and complementary bioassembly techniques at the intersection of biology and engineering. Biofabrication is promising for printing of transplantable tissues, though near-term applications in practice include biomimetically engineered models for drug discovery, cosmetics testing, tissue regeneration and medical devices. Recapitulating the structure and complexity of native tissues, however, remains a significant challenge. To address this, recent biofabrication work has demonstrated improvements in the scale, rate and intricacy at which tissues can be fabricated, with examples including work in volumetric bioprinting, scaffold-free bioassembly, and hybrid biofabrication strategies. These and other emerging techniques have the potential for the strategic arrangement of multiple materials, cells and extracellular matrix components at length scales down to the level of single cells. This review evaluates emerging biofabrication techniques and highlights their recent application and future potential in producing complex heterogeneous tissues.