3D printed blood vessel ice template
Philip LeDuc and others/Carnegie Mellon University
Complex artificial organs can be created by 3D printing molds of veins, arteries, and capillaries in ice, casting them in organic materials, and melting the ice to form delicate, hollow networks. This leaves space for the complex vascular grafts required for the development of laboratory-cultured internal organs.
Researchers have been working for decades to develop artificial organs to meet the high global demand for transplants such as hearts, kidneys and livers. However, creating the vascular network necessary to keep them alive remains a challenge.
Existing technology can grow artificial skin and ears, but the meat and organ materials disappear when they are more than 200 micrometers away from blood vessels. Philippe Leduc at Carnegie Mellon University in Pennsylvania.
“It's about twice the width of a hair. Once you get through that, and you can't access nutrients anymore, your cells start dying,” he says. Therefore, new processes will be needed to produce internal organs cheaply and quickly.
LeDuc and his colleagues experimented with printing blood vessels with meltable wax, which requires fairly high temperatures and can leave behind residue. “One day, out of the blue, a student of mine said, 'What if we tried using water, the most biologically compatible substance in the world?'” he says. “And I'm like, 'Oh, yeah.' It still makes me laugh. It's that simple.”
They developed a technique that uses a 3D printer to create a mold of the inside of an organ's blood vessels in ice. In the test, they embedded them in a gelatin material that hardens when exposed to ultraviolet light before the ice melts away.
The researchers used a platform cooled to -35°C and a printer nozzle that ejected hundreds of drops of water per second, allowing them to print structures as small as 50 micrometers in diameter.
LeDuc says the process is conceptually simple, but requires complete coordination. If the droplet is ejected too quickly, the droplet will not solidify quickly enough to create the desired shape, but if it prints too slowly, it will just form a clump.
The system is also affected by weather and humidity, so researchers are looking into using artificial intelligence to adjust the printer to different conditions.
They also used a version of water in which all the hydrogen was replaced with deuterium, a stable isotope of the element. This so-called heavy water has a high freezing point and helps create a smooth structure by avoiding unwanted crystallization. Deuterium is not radioactive, unlike some isotopes, and tests have shown it to be safe for creating artificial organs, LeDuc said.
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Source: www.newscientist.com
