Scientists from Brigham and Women's Hospital in Boston, Mass., have successfully used 3D-printing to replicate human blood vessels.

The experiment marks the first time that synthetic blood vessels were created, according to RT.

Blood vessels are extremely fragile, and are more delicate than anything that has been synthetically bio-printed before.

"Creating artificial blood vessels remains a unique challenge in tissue engineering," said Ali Khademhosseini, biomedical engineer and project leader. "We've attempted to address this challenge by offering a unique strategy for vascularization of hydrogel constructs that combine advances in 3D bio-printing technology and biomaterials."

The scientists used a process that first prints agarose, a sugar-based molecule, and then fibers to serve as templates for the vessels, Engadget reported.

They then created a cast by covering the resulting mold in a jelly-like hydrogel.

Khademhosseini said they covered the channels with the hydrogel to make sure that "the fiber templates we printed are strong enough that we can physically remove them to make the channels." He added that this is important because it "prevents have to dissolve these template layers, which may not be so good for the cells that are entrapped in the surrounding gel," RT reported.

The team created micro-channel networks, which were embedded into different types of gel to show their durability. Endothelial monolayers also successfully grew inside the synthetic channels.

The inner walls of blood vessels are lined with endothelium, a layer formed out of endothelial cells that filter fluids, traffick hormones, perform hemostasis, and accomplish other important tasks, RT reported. The synthetic blood cells need the endothelium, or else they would only be extremely thin tubes.

"In the future, 3D printing technology may be used to develop transplantable tissues customized to each patient's needs, or be used outside the body to develop drugs that are safe and effective," Khademhosseini said.

The research was published in the journal Lab on a Chip.