Scientists are working to build blood vessels from human cells using tiny ice sculptures – these cool 3D shapes twist and branch like real arteries and can be used as temporary scaffolds that are later melted, to be replaced with living cells.
Researchers demonstrated the first step of this blood vessel building process in a recent study by creating scaffolds using a 3D “ice printing” technique. The scaffolds were then coated with a gel that was embedded with human cells, which the team grew for about two weeks.
The ice printing technique could one day be used to make realistic blood vessels, grown in the lab from human cells that capture the “complex geometries” of real vascular networks in the body, the study’s researcher said. Feimo Yanga doctoral candidate in mechanical engineering at Carnegie Mellon University, told Live Science.
“Currently, this is more of a proof of concept,” Yang said, but with development, this technique could be useful for fabricating blood vessels that can be transplanted into a person when they need repair, replacement or bypass. of an artery or vein.
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Doctors currently harvest blood vessels for transplantation from elsewhere in a patient’s body or from a donor. For some procedures, clinicians may use artificial blood vessels made of synthetic polymers; natural materials, such as proteins; or a mixture of both. However, these artificial blood vessels do not perfectly replicate real ones and can fail, in part because they are not living.
This is where ice printing can provide an advantage; could help scientists create more realistic structures from real human cells.
Small-scale ice printing can also be useful to create so-called organ-on-a-chip device, Yang added. Such devices use fluids flowing through many tiny channels to support cell growth, and they act as miniature models of organs in the human body.
The team’s new work — which Yang will present at the 68th Annual Meeting of the Biophysical Society Feb. 10-14 in Philadelphia — was built on the back of a printing technique called 3D-ICE , first described in a 2022 paper in the journal. Advanced science.
Our work on #ice #3Dprinting at the #microscale was featured in Additive Manufacturing! “almost like witnessing something magical…seems more like it belongs in a nature documentary” #CarnegieMellon #biomedical #microfluidics #AdditiveManufacturinghttps://t.co/j1u6qM3vLxJanuary 25, 2023
The printer uses water as its “ink” and works by dripping water droplets onto a cold copper surface, which is kept at minus 31 degrees Fahrenheit (minus 35 degrees Celsius). When a drop of water hits the surface, it freezes quickly and each successive drop adds to the growing ice sculpture.
The printer ejects about 200 drops of water per second, Yang said. This speed is slow enough to enable one water droplet to begin freezing before hitting another, but fast enough that the droplets still freeze together in a smooth structure, rather than forming defined layers. If the drops fell also quickly, one liquid water droplet would join another and spread out before freezing, Yang explained.
The dots themselves are about 50 micrometers in diameter, so the resulting structures can be made with micron-level detail. And the printing technique is fast. The sculptures the team made were about 0.1 inches (3 millimeters) long and 0.008 inches (0.2 mm) in diameter, and “take maybe 20 seconds” to print, Yang said.
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There are other ice printing techniques that build small sculptures layer by layer OR volume by volume, but these are not great at creating smooth surfaces. 3D-ICE, in contrast, can create smooth, free-flowing shapes closer to what is seen in human circulatory system.
After creating a small sculpture with their ice printer, Yang and colleagues coated the structure with a gelatin-based material. Because their printer specifically uses “heavy water” — in which hydrogen atoms are replaced by deuterium — the ice stays frozen at temperatures above freezing. This meant the researchers could work at temperatures where their gel remained pliable while the ice remained frozen.
Using ultraviolet light, they melted the ice and solidified the gel, leaving smooth channels that closely resemble blood vessels. The team then added cells that line blood vessels, called endothelial cells, to the gel and showed they could grow the cells for two weeks. In the future, they will experiment with growing the cells for longer.
While it will be some time before 3D-ICE can be used to create blood vessels destined for the body of a human patient, “hopefully, we will be able to expand the use of this technology,” Yang said.
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