Living tissues rely heavily on vascular networks to transport nutrients, oxygen and metabolic waste. However, there still remains a need for a simple and efficient approach to engineer vascularized tissue, This has been one of the biggest hurdles to 3D bioprint more complex functional tissues than basic cartilage and, with still limited capacity, skin.
A team of Chinese researchers at University of California at San Diego La Jolla created prevascularized tissues with complex three-dimensional (3D) microarchitectures using a rapid bioprinting method called microscale continuous optical bioprinting (μCOB), a technique which uses light to rapidly cure a bioprinting hydrogel.
Multiple cell types mimicking the native vascular cell composition were encapsulated directly into hydrogels with precisely controlled distribution without the need of sacrificial materials or perfusion. With regionally controlled biomaterial properties the endothelial cells formed lumen-like structures spontaneously in vitro.
Endothelial cells, in a single layer, make up the Endothelium that lines the interior surface of blood vessels and lymphatic vessels, forming an interface between circulating blood or lymph in the lumen and the rest of the vessel wall.
In vivo implantation demonstrated the survival and progressive formation of the endothelial network in the prevascularized tissue. A surgical connection (anasthomosis) between the bioprinted endothelial network and host circulation was observed with functional blood vessels featuring red blood cells.
The scientists have concluded that with the superior bioprinting speed, flexibility and scalability, this new prevascularization approach could be broadly applicable to the engineering and translation of various functional tissues in the future, thus marking another small step toward the long term goal of engineering more complex tissues and organs in the lab.