Scientists are developing a method to create blood vessels from human cells using small ice sculptures. These miniature 3D structures resemble real arteries by branching and twisting. They work as temporary scaffolds that get melted away and replaced by living cells later.
To demonstrate the first stage of the blood-vessel-building process, the researchers utilized a 3D “ice printing” technique to create scaffolds. The scaffolds were then covered in a gel containing human cells, which the team grew for two weeks.
The ice printing technique has the potential to produce realistic, lab-grown blood vessels from human cells that replicate the intricate geometries of actual vascular networks in the body. Feimo Yang, a doctoral candidate in mechanical engineering at Carnegie Mellon University, stated that this technique could be used in the future for creating such blood vessels.
“Currently, this is more of a proof of concept,” Yang said, but with development, this technique might be useful for fabricating blood vessels that could be transplanted into a person when they need an artery or vein repaired, replaced or bypassed.
Doctors currently extract blood vessels for transplant from other parts of a patient’s body or from a donor. However, artificial blood vessels made from synthetic polymers or natural materials such as proteins may also be used. Despite this, these artificial blood vessels are not identical to real ones and may fail because they are non-living.
In contrast, ice printing could help create more realistic structures using real human cells. This technique could also be useful for crafting organ-on-a-chip devices, which use fluids to sustain cell growth through tiny channels. These devices act as miniature models of organs in the human body.
A team of researchers will present their new work at the 68th Biophysical Society Annual Meeting being held from Feb. 10 to 14 in Philadelphia. The work is based on a printing technique called 3D-ICE, first described in a 2022 paper in the journal Advanced Science.
The printer uses water as its “ink” and drips drops of water onto a cold copper surface kept at minus 31 degrees Fahrenheit (minus 35 degrees Celsius). Each successive drop adds to the growing ice sculpture by quickly freezing when it strikes the surface. The printer spits out about 200 drops of water per second, which is slow enough to enable one water drop to freeze before the next one hits. If the drops fell too fast, they would merge into each other and spread out before freezing.
The drops are about 50 micrometers in diameter, enabling the creation of micron-level details in resulting structures. The printing technique is also fast, taking only about 20 seconds to print structures that stand about 0.1 inch (3 millimeters) tall and 0.008 inch (0.2 mm) in diameter.
Unlike other ice printing techniques, 3D-ICE can create smooth, free-flowing shapes that resemble those found in the human circulatory system. After creating a sculpture with their ice printer, the researchers coated it in a gelatin-based material. The use of “heavy water” allows the ice to stay frozen above-freezing temperatures, which enables the researchers to work with the gel while the ice remains frozen.
Using ultraviolet light, they melted the ice away and hardened the gel, leaving smooth channels that resemble blood vessels. The team then added endothelial cells, which line blood vessels, to the gel and demonstrated that they could grow the cells for two weeks. In future work, they will experiment with growing the cells for longer periods.
While it will be some time before 3D-ICE could be used to craft blood vessels destined for a human patient’s body, “hopefully, we’ll be able to expand the use of this technology,” Yang said.