The likelihood of 3D printing functional organs just took a huge step forward, with scientists at the University of California working out a way to print not just the organ, but also the blood vessels needed to transport nutrients, oxygen and metabolic waste.
The researchers used what is called a "rapid bioprinting method", AKA microscale continuous optical bioprinting (μCOB). Here's the hard science:
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.
In vivo implantation demonstrated the survival and progressive formation of the endothelial network in the prevascularized tissue. Anastomosis between the bioprinted endothelial network and host circulation was observed with functional blood vessels featuring red blood cells.
Basically, they can 3D print the organs and all of the blood vessels they need to be function in the body at once.
Due to the speed and flexibility of this method, this means nothing short of a breathrough for 3D printing organs on a large scale.