Blood vessels made with 3D-printed ice could improve lab-grown organs

Complex prostheses can be made by 3D printing by placing a mold of veins, arteries and capillaries in ice, embedding it in organic material and then allowing the ice to melt, resulting in a delicate, hollow mesh. Is. This leaves room for the complex artificial blood vessels needed to grow lab-grown internal organs.

Researchers have been working on artificial organs for decades to meet the high global demand for heart, kidney and liver transplants. But building the blood vessel networks necessary for survival is still a challenge.

Artificial skin or ears can be grown with current techniques, but if any flesh or organ is lost more than 200 micrometers from a blood vessel. Philip Le Dick at Carnegie Mellon University in Pennsylvania.

It is twice the width of a hair. After that, cells start to die if there is no access to nutrients,” he says. So internal organs need new processes if they are to develop cheaply and quickly.

LeDuc and his colleagues experimented with printing blood vessels with waxes that can melt, but require reasonably high temperatures and can leave residue. “All of a sudden, one day, my student went ‘why don’t we just use water – the most biologically compatible material in the world?'” says LeDuc. “And I’m like, ‘Oh, yeah.’ It still makes me laugh. It’s so straightforward.”

They developed a technique that uses 3D printers to create a mold of the inside of an organ’s blood vessels in ice. In tests, these were then embedded in a gelatin material that hardens when exposed to ultraviolet light before the ice melts.

The team used a platform cooled to -35°C and a printer nozzle that dispenses hundreds of water droplets per second, allowing structures as small as 50 micrometers to be printed.

LeDuc says the process is conceptually simple but requires fine-tuning — dispensing drops fall too quickly and they don’t freeze fast enough and fail to form the desired shape, but they are very Print slowly and they just lump.

The system is also affected by weather and humidity, so researchers are investigating its use. Artificial intelligence To adapt the printer to different situations.

They also used a version of water in which all the hydrogen was replaced by deuterium, a stable isotope of the element. This so-called heavy water has a high freezing point and helps to form a smooth structure by avoiding unwanted crystallization. LeDuc says tests have shown that it will be safe when making prostheses because deuterium is not radioactive, unlike some isotopes.