Since he was 4 years old, University of Minnesota freshman Anders Jenson has had four open-heart surgeries.
When patients like Jenson are missing valves or tubes in their heart, surgeons can implant synthetic ones but must replace them often because they don’t grow with other body parts. Now, after 25 years, University researchers have created a new type of artificial artery that grows by itself and can work in more patients without specialization.
The University team behind the project published a study last week showing the success of their implant in sheep.
The team hopes using an implant that grows with the patient over time will mean only one surgery in a lifetime, said Robert Tranquillo, a University biomedical engineering professor and co-author on the study.
“As the patient grows and the tubes don’t, there’s restricted blood flow, and they need to implant a bigger tube. These are open-heart surgeries. … You can imagine how traumatic that is,” Tranquillo said.
Each new surgery can also stress the heart, making additional surgeries more difficult and dangerous.
“Over a lifespan, it could be three or four [surgeries],” said Dr. Gwenyth Fischer, Pediatric Device Innovation Consortium director and assistant professor of pediatrics.
Jenson, whose most recent surgery was four years ago, said he now requires surgical specialists after the stresses of previous operations.
The repeat surgeries for those with these types of conditions can be extremely draining. Jenson said he gets his operations done over summer breaks and spends the entire period sluggish and unable to do any physical activity.
“I don’t even remember the [week after a surgery],” he said. “I was sleeping the entire time. There’s not much else I can do.”
Tranquillo said other groups have made artificial, growing tubes, but these devices needed to be laced with patient’s cells before use and aren’t made of organic tissue.
Meanwhile, the new tube works “off the shelf” without any patient cells inside it. This helps avoid issues with the host’s immune system, said Zeeshan Syedain, lead author of the study.
“Our [implant] doesn’t require patient cells. … We can implant this into any other person without risking a … response,” Tranquillo said.
While most other devices are made of plastic or other synthetics, this model is made to let host cells join with it and grow like a natural tube after it gets attached to the patient, he said.
When the tube is in the heart, cells flowing through fill its structure. These cells can grow with the body, Tranquillo said.
“It becomes living again after it’s implanted. … It’s becoming like an artery again,” he said.
The tubes also have “growth factors” left from when researchers made them in the lab, Tranquillo said. These chemicals help tell the body to adopt the implant.
Heart implants are often accompanied by drug regimens to prevent clotting and other complications.
The team’s model requires that patients take anticoagulants, but as the cells grow into the tube, patients could potentially go without them, Syedain said — but more research needs to be done to know for certain.
Tranquillo said the lab will also design an artificial valved tube with leaflets, or small flaps that prevent deoxygenated blood from flowing in the wrong direction. This could be used to treat different kinds of heart defects.
“If we can make a valve that grows along with the tube, that would allow us to address essentially all … defects,” he said.
In the future, Jenson wants to be a pediatric cardiologist and use new treatments like the artificial tube to treat heart conditions like his own more effectively.
“A big concern for me is how long will I be able to continue to have all these open-heart surgeries? … I want to make it easier for kids with heart disease,” Jenson said. “I’ve experienced the inefficiencies of our current treatments. I don’t think it’s right.”