Researchers from the from the University of Sydney, Harvard, Stanford, and MIT have successfully bio-printed artificial vascular networks that mimic the body's circulatory system. These networks are necessary for growing large complex tissues and, eventually, organs.

The breakthrough has been published in "Hydrogel Bioprinted Microchannel Networks for Vascularization of Tissue Engineering Constructs" in the journal Lab on a Chip.

In an interview, lead author of the paper and University of Sydney researcher Luiz Bertassoni, PhD, describes the significance of the study.

Bertassoni says, "One of the greatest challenges to the engineering of large tissues and organs is growing a network of blood vessels and capillaries."

"Imagine 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 in your computer screen," he enthuses.

"We are still far away from that, but our research is addressing exactly that. Our finding is an important new step towards achieving these goals. At the moment, we are pretty much printing 'prototypes' that, as we improve, will eventually be used to change the way we treat patients worldwide."

The researchers first fabricated a multitude of interconnected tiny fibers to serve as the mold for the artificial blood vessels. They then covered the 3-D printed structure with a cell-rich protein-based material which was cured by applying light to it. Then they removed the bio-printed fibers, leaving behind a network of tiny channels coated with human endothelial cells. These cells self organized to form stable blood capillaries in less than a week.

The study revealed that the bioprinted vascular networks promoted significantly better cell survival, differentiation, and proliferation compared to cells that received no nutrient supply.

"To illustrate the scale and complexity of the bio-engineering challenge we face, consider that every cell in the body is just a hair's width from a supply of oxygenated blood," Bertassoni says. "Replicating the complexity of these networks has been a stumbling block preventing tissue engineering from becoming a real-world clinical application."

"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," he says.

"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."

Stephen Levy is a contributor to Qmed and MPMN.

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