A team of scientists based at Brigham and Women’s hospital has made significant progress towards the manufacture of blood vessels for tissue engineering using 3D bioprinting. The study has been published in Lab on a Chip.

Tissue engineering has come along leaps and bounds in recent years, but one obstacle that scientists have found difficult to overcome is vascularization. Vascular networks that facilitate the transport of nutrients and oxygen and removal of waste products from the tissues prevent the cells from dying and therefore extend the life of the engineered construct. Furthermore, when the constructs are implanted into recipients, blood vessels are slow to penetrate the tissue. The success of the transplant therefore relies heavily on the development of vascular networks in the engineered constructs.

“Engineers have made incredible strides in making complex artificial tissues such as those of the heart, liver and lungs,” said senior author Ali Khademhosseini in a press release. “However, creating artificial blood vessels remains a critical 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 printing technology and biomaterials.”

The team first bioprinted a 3D blood vessel template composed of agarose fibers, which was then covered in a hydrogel precursor substance. This substance was then photocrosslinked and the blood vessel template within removed, resulting in perfusable microchannels with various architectural features. The team was able to embed these functional microchannels within various different hydrogel materials, and they demonstrated that these networks could improve transport and cellular viability within tissue constructs. But perhaps more importantly, the team showed that monolayers of endothelial cells successfully formed within the microchannels.

“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,” said Khademhosseini.