Scientists bioprint functional blood vessels

They used a merger of volumetric bioprinting techniques and melt electrowriting.
Loukia Papadopoulos
An illustration of blood vessels.jpg
An illustration of blood vessels.


Bioprinting blood vessels is key for medical uses however current methods for carrying out this process are done in cell-friendly gels resulting in prints that are structurally not very sound. This becomes especially problematic for blood vessels, which have to be able to withstand high pressures and bending. 

To solve this issue, researchers at University Medical Center Utrecht pursued a merger of volumetric bioprinting techniques and melt electrowriting.

This is according to a press release by the institution published on Wednesday.

For the uninitiated, melt electrowriting is a highly accurate type of 3D printing that works by directing a narrow filament of molten (biodegradable) plastic. The end result is intricate scaffolds that are mechanically strong and able to deal with force. 

However, these scaffolds can’t be printed with cells in there directly, because of the high temperatures involved. That’s where volumetric bioprinting comes into play as the method can be used to solidify cell-laden gels onto the scaffolds.

To get functional blood cells, the scientists created a tubular scaffold using melt electrowriting and proceeded to submerge it into a vial with photoactive gel and place it in the volumetric bioprinter. 

“In order to get this right, we had to place the scaffold exactly center in the vial,” first author of the new study Gabriël Größbacher said. “Any deviation from the center would mean that the volumetric print would be off-set. But we managed to center it perfectly by printing the scaffold on a mandril that we fitted to the vial.”

Various thickness, stronger tubes

Größbacher and colleagues found that various thicknesses of the scaffold produced more or less strong tubes. They also tested various placements of the bioprinted gels either on the inner side of the scaffold, inside the scaffold itself or on the outside of it. 

Through trial and error, the team was successful at printing a proof of principle blood vessel with two layers of stem cells, and seeded epithelial cells in the center to cover the lumen of the vessel.

Perhaps what’s most impressive is that the design could also allow for holes in the side of the print, giving the possibility for controlled permeability of the vessel for the blood to do its function. 

“This was a proof of principle study. What we now need to do is replace the stem cells with functional cells that are part of a real blood vessel. That means adding muscle cells and fibrous tissue around the epithelial cells. Our goal now is to print a functional blood vessel,” Größbacher concluded in the statement.

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