Researchers from the University of California at San Diego have 3-D printed a vascular network that can safely combine with a host network to circulate blood, in a breakthrough that takes the bioprinting of blood vessels to another level, according to a report on the UC San Diego website.
Nanoengineering professor Shaochen Chen 3D prints a biomimetic blood vessel network.
(Erik Jepsen/UC San Diego Publications)
Previous attempts at developing 3-D printed blood vessels have been limited to single structures rather than networks and have also proven to be slow and costly.
Nanoengineering professor Shaochen Chen and his team used homemade 3-D printers to quickly produce intricate microstructures that mimic biological tissues. In the past, Chen has used this technology to create liver tissue among other items.
The article explained, “Researchers first create a 3D model of the biological structure on a computer. The computer then transfers 2D snapshots of the model to millions of microscopic-sized mirrors, which are each digitally controlled to project patterns of UV light in the form of these snapshots. The UV patterns are shined onto a solution containing live cells and light-sensitive polymers that solidify upon exposure to UV light.”
The structure is continuously printed layer by layer to create a 3-D solid polymer scaffold around live cells that will grow to become biological tissue. The researchers have been able to print with higher resolution than previous attempts, which saves on the steps required to build the tissue. In fact, the process only takes a few seconds.
The article continued, “Chen’s team used medical imaging to create a digital pattern of a blood vessel network found in the body. Using their technology, they printed a structure containing endothelial cells, which are cells that form the inner lining of blood vessels.”
Researchers grafted the cultures into the skin wounds of mice and after two weeks saw that the implants had merged into the host’s blood vessel network and that blood was circulating normally.
Among the developments that researchers will be testing in the future include using patient-specific stem cells that will avoid being attacked by host immune systems and to allow the blood vessels to perform other function such as transporting nutrients or waste.
The research was recently published in Biomaterials. The abstract stated:
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 tissues.
“Here, we created prevascularized tissues with complex three-dimensional (3D) microarchitectures using a rapid bioprinting method – microscale continuous optical bioprinting (μCOB).
“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.
“With the superior bioprinting speed, flexibility and scalability, this new prevascularization approach can be broadly applicable to the engineering and translation of various functional tissues.”