‘Critical challenge’: Doctors can now 3D-print blood vessels
Although huge strides have already been made in replicating all sorts of human tissue and organs, making delicate conduits from scratch was still some way off from reality. Now, by approaching the problem in a complex way involving several layers, vessels were engineered in a fashion conducive to the health of the blood vessel cells, which makes for more long-lasting vessels.
There is no other way to approach something that lines our entire bodies, performing the crucial function of delivering nutrients and siphoning off bad materials and waste in order to keep our organs alive. Blood vessels are incredibly fragile things – their constitution is infinitely more delicate than anything science has tried to synthetically bio-print before, because this particular brand of printing organs involves considerations on a cellular level. The study was published in the journal Lab on a Chip recently.
As biomedical engineer and project leader, doctor Ali Khademhosseini explained, “creating artificial blood vessels remains a unique challenge in tissue engineering. 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.”
To do this, his team first 3D-printed something called agarose fiber templates, which are designed to be removed at a later date. The resulting mold is then covered in a liquid, yet durable substance called hydrogel, which coats the channels.
This durable combination ensures that “the fiber templates we printed are strong enough that we can physically remove them to make the channels," Khademhosseini said, explaining that this is crucial because it “prevents having to dissolve these template layers, which may not be so good for the cells that are entrapped in the surrounding gel.”
The team was able to construct micro-channel networks that display a range of architectural features. Embedding these networks into different types of gel showed their durability. However, the real magic of science here was the successful growth of endothelial monolayers inside the synthetic channels.
This process needs to be explained in more detail to the layman: the interior walls of blood vessels are lined with a special layer called endothelium, formed out of endothelial cells. The cells perform the key functions of vascular biology by filtering fluids, trafficking hormones, hemostasis and others. Without that layer, the amazing synthetic blood vessels would essentially just be impressively thin tubes.
As Khademhosseini put it enthusiastically, "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."