The novel study, headed by Nanoengineering lecturer Shaochen Chen, addresses one of the biggest limitations in tissue engineering, preparing lifelike organs and tissues with functioning vasculature, networks of blood vessels that can transport blood, waste, nutrients and other biological substances and do so securely when implanted inside the body.
Scientists from other labs have used 3D printing technologies to prepare artificial blood vessels. But present technologies are slow, expensive and mainly produce simple structures, like single blood vessel, a tube, usually. These blood vessels also are not efficient of integrating with the body’s own vascular system.
“Almost all the organs and tissues require blood vessels to survive and work properly. This is a huge bottleneck in making organ transplants that are in high demand but in short supply,” says Chen, who headed the Nanobiomaterials, Bioprinting and Tissue Engineering Lab at the UC San Diego. “3D bioprinting organs can help bridge this gap, and our lab has taken a huge step toward the goal.”
Chen’s group introduced an innovative bioprinting technology, using their own homemade 3D printers, to rapidly produce complex 3D microstructures that copy the sophisticated functions and designs of biological tissues. The lab of Chen has used this technology in the past to prepare liver tissue and microscopic fish that can swim in the body to identify and eradicate toxins.
Scientists first prepare a 3D model of the biological structure on a computer. The computer then transmits 2D snapshots of the model to millions of microscopic – sized mirrors that are each digitally regulated to project patterns of UV light in the form of such snapshots. The UV patterns are shined onto a solution comprising live cells and light-sensitive polymers that solidify upon exposure to UV light. The structure is swiftly printed one layer at a time, in a regular fashion, preparing a 3D solid polymer scaffold encapsulating live cells that will expand and become biological tissue.
Chen’s group used medical imaging to prepare a digital pattern of a blood vessel network found in the body. Using their technology, they printed a structure comprising endothelial cells, which are cells that form the inner lining of blood vessels. Scientists cultured numerous structures in vitro for one day then grafted the resulting tissues into skin wounds of mice. After couple of weeks, the scientists examined the implants and found that they had successfully grown into and merged with the host blood vessel network, enabling blood to circulate normally.
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