The nimble fingers of skilled surgeons restore blood flow by stitching together millimeter-scale arteries in reconstructive procedures and organ transplants. However, a 3D-printed stent full of sugar may help ease these medical procedures.
Designed by University of Nebraska engineer Ali Tamayol and nationwide colleagues, the small sugar-based tube fits inside adjacent ends of a clipped artery. The stent holds those ends in place, sticking to the interior and providing structural support during stitching.
“One of the plastic surgeons told us about the challenges of this kind of microsurgery – how time-consuming it is, how skill-dependent it is,” notes Tamayol, assistant professor of mechanical and materials engineering.
The team reports stent-assisted suturing takes 5 minutes when tested on pig arteries, compared to 15 minutes for the conventional clamp-based technique, and minutes after suturing the resuming blood flow dissolves the stent and harmlessly sweeps it away. The stent also reduces the risk of a surgeon mistakenly threading through the top and bottom walls of an artery, which blocks subsequent blood flow.
Customized with 3D printing
In designing the medical device, researchers came up with a checklist of essential properties. It needed some flexibility – too brittle, and it could break during suturing – so the team added a glucose derivative called dextran. It required enough stickiness to bind with the arteries, which glucose itself provided, plus a large dose of sucrose to help combat blood clotting. And it needed a pinch of sodium citrate to further diminish any chance of clotting when it dissolved.
The recipe was simple enough, but arteries come in multiple sizes, so the team used 3D printing to customize the stent’s diameter to individuals and areas in the body. By dissolving their sugar-based concoction in water and baking the solution until most of the water evaporated, researchers produced a molten ink fluid enough to print but viscous enough to solidify in minutes.
Experiments with transparent tubing and pig arteries showed that the stent erodes quickly but steadily when subjected to the flow rate, temperature, and salinity of human arteries. The suturing also held up without any signs of leakage immediately following the procedure.
The researchers eventually plan to test the stent’s use in live animal arteries, Tamayol says. They envision a future where such stents are printed at hospitals to meet the needs of individual patients.
“One thing that I really like about this concept: We are always trying to avoid sugar,” Tamayol says. “Everyone knows that sugar is (sometimes) bad. But here we found an application where it’s good.”
University of Nebraska-Lincoln