3D-Printed Blood Vessels Could Improve Outcomes for Heart Bypass Patients

Given the prevalence of cardiovascular disease, small-diameter vascular grafts are in high demand for blood vessel reconstruction and heart bypass surgeries. However, the existing options for such grafts often fall short of expectations, as they fail to match the biomechanical properties of native human arteries.

Now, researchers from the University of Edinburgh have developed a new fabrication technique that uses extrusion printing and electrospinning to 3D print artificial blood vessels that closely mimic the properties of human veins. The research is published in Advanced Materials Technologies.  

Synthetic blood vessels to improve surgical outcomes

To re-route blood flow away from a blocked artery, heart bypass surgeries require the use of some form of replacement blood vessel. This could be a synthetic vein or the transplant of a human vein taken from elsewhere in the body.

Neither of these approaches are perfect. Most synthetic blood vessel grafts are only suitable for large-diameter arteries, which limits their usefulness in some blood vessel reconstruction or heart bypass surgeries. The surgical graft option is also less than ideal, with graft failure rates being relatively high and the harvest site sometimes developing complications. Additionally, neither graft option offers a perfect match in terms of their mechanical properties.

“The currently available vascular graft options include synthetic grafts that are made from polymers and patient’s own veins usually taken from the leg,” explained principal investigator Dr. Norbert Radacsi, senior lecturer in chemical engineering at the University of Edinburgh. “The compliance mismatch between these grafts and the blocked artery is the major challenge that often leads to failure. Whereas, the flexibility of our engineered grafts can be altered by using different polymer combinations to match the compliance of an artery or vein that needs to be replaced.”

The new graft options developed by Radacsi’s team are built in a two-stage process, which combines bioprinting with electrospinning, to create small-diameter artificial vessels with tunable mechanical properties.

“The newly developed 3D printing system uses a rotating vertical mandrel and an extrusion tip to print hydrogel, which includes a modified gelatine and water. The printing parameters were carefully controlled to print a tubular construct around the rotating mandrel,” Radacsi said. “Subsequently, the grafts were reinforced using an electrospinning technique, in which the nanofibers 200 times thinner than the human hair were deposited over the printed hydrogel.”

These electrospun nanofibers are made using a blend of polycaprolactone (PCL) and poly(L-lactide-co-ε-caprolactone) (PLCL) polymer solutions. By varying the composition of this blend, the team was able to change how compliant or firm their artificial vessels were. Hydrogels reinforced by 100% PCL nanofibers had similar compliance to human muscular arteries, the researchers found, while a 75/25% PCL/PLCL blend was a match for human elastic arteries.

Radacsi believes that these new synthetic vessels could help limit the scarring, pain and infection risk associated with bypass surgeries. Approximately 20,000 bypass operations are carried out in England each year. The team is now pursuing animal trials of these blood vessels, in collaboration with the University of Edinburgh’s Roslin Institute.

“After getting the promising results, animal studies on pigs will be conducted to assess the long-term suitability of these grafts. Upon success, this will be followed by trials in humans,” Radacsi said.

Reference: Fazal F, Melchels FPW, McCormack A, et al. Fabrication of a compliant vascular graft using extrusion printing and electrospinning technique. Adv Mater Technol. 2024:2400224. doi: 10.1002/admt.202400224

Dr. Norbert Radacsi was speaking to Alexander Beadle, Science Writer for Technology Networks.

About the interviewee:

Dr. Norbert Radacsi studied physics and general medicine at the University of Debrecen, Hungary. He graduated with an MSc in physics in 2006. Norbert obtained his PhD in chemical engineering from the Delft University of Technology, the Netherlands in 2012.

He received postdoctoral training from Delft University of Technology, Purdue University and California Institute of Technology.