Scientists print blood vessels to keep tissue alive

In what could be another major step forward for bioengineering, a group of researchers has produced a functioning vascular network that can keep engineered tissues alive —with sugar and a customized 3-D printer.

 

The vascular network, which brings in oxygen and nutrients and removes wastes from the tissue, was built at the University of Pennsylvania, IEEE.org reported.

 

“One of the keys to the project was being able to use an open-source 3-D printer like RepRap, which can be freely modified. Several of the parts used to customize the team's RepRap were printed in plastic from another RepRap,” IEEE.org said.

 

Jordan Miller, a post-doc at the university who co-led the research team, said he got the idea after visiting a Body Worlds exhibition, where he saw plastic casts of whole-organ blood vessels on display, it said.

 

With the custom RepRap 3-D printer, the scientists were able to turn the mixture into a free-standing, three dimensional vascular template.

 

“The sugar template creates a temporary set of guiding pipes where fluid will flow. After it is printed, it is coated in a thin layer of corn-based degradable polymer to help stabilize the sugar. Miller and his colleagues then pour living cells around the template to encapsulate it in what becomes solid tissue,” it said.

 

It added the sugar template dissolves leaving a bare vascular network through which nutrient-rich fluid can flow.

 

Researchers can leave the channel walls bare or seed them with cells that attach to the walls and form a lining, IEEE.org said.

 

Miller and professor of bioengineering Christopher Chen published their design this week in Nature Materials.

 

Tweaking printing process

 

IEEE.org said scientists have been experimenting with 3-D printing and cells for years, experiencing problems with the vasculature.

 

While their most common technique is a layer-by-layer bio-printing where single layers of cells and gel are created and assembled one at a time, the vasculature has remained a major challenge.

 

Before, scientists had tried leaving hollow channels in the layers, but the channels have structural seams that can fall apart with the pressure of fluid pumping.

 

This time, IEEE.org said Chen and his colleagues printed the vasculature first, instead of trying to print a large volume of tissue in layers and leaving hollow channels.

 

Redesigning printer

 

Miller says he plans to redesign the printer from scratch to focus entirely on cell biology, tissue engineering and regenerative medicine applications.

 

“Jumping on the 3-D printing bandwagon, he will teach a class on building these types of printers at a workshop this summer,” IEEE.org said. — TJD, GMA News