Bio-printing transplantable tissues a step closer

A bio-printed artificial vascular network capable of mimicking the body’s circulatory system could bring the possibility of printing transplantable tissues and organs a step closer. “Imaging being able to walk into a hospital and have a full organ printed – or bio-printed, as we call it – with all the cells, proteins and blood vessels in the right place, simply by pushing the ‘print’ button on your computer screen,” said Dr Luiz Bertassoni from the University of Sydney. Cells need a readily available supply of nutrients, oxygen and an effective waste transport system to sustain life and but replicating the complex vascularisation system has proved difficult. “One of the greatest challenges to the engineering of large tissues and organs is growing a network of blood vessels and capillaries,” said Bertassoni, lead author of the study published in Lab on a Chip. “Replicating the complexity of these networks has been a stumbling block preventing tissue engineering from becoming a real world clinical application.” Bertassoni, together with scientists from Harvard, Stanford and MIT, used a high-tech bio-printer to manufacture several tiny interconnected fibres to serve as the mould for artificial blood vessels. They covered the structure with a cell-rich protein-based material, which was solidified by the application of light, before removing the bio-printed fibres to leave behind a network of channels coated in human endothelial cells. Within a week, these had self-organised to form stable blood capillaries. The study revealed that the bio-printed vascular network promoted significantly better cell survival, differentiation and proliferation compared to cells with no nutrient supply. Bertassoni said a major benefit of this technique is the ability to manufacture large 3D microvascular channels capable of supporting life on the fly, with enough precision to match individual patients’ needs. "While recreating little parts of tissues in the lab is something that we have already been able to do, the possibility of printing three-dimensional tissues with functional blood capillaries in the blink of an eye is a game changer," said Bertassoni. "Of course, simplified regenerative materials have long been available, but true regeneration of complex and functional organs is what doctors really want and patients really need, and this is the objective of our work.” Hydrogel bioprinted microchannel networks for vascularization of tissue engineering constructs