Bioengineered vein paves way for kidney dialysis patients

Jun. 12, 2013 @ 04:03 PM

Sixty-two-year-old Lawrence Breakley from Danville, Va., became the first U.S. patient to receive a bioengineered vein transplant at Duke University Hospital this month. 

 

The surgery took only two hours, but for Duke researchers and RTP scientists, the groundbreaking medical invention has been more than a decade in the making.

The brand-new blood vessel created from human cells and biodegradable scaffolding may lead to future surgical fixes for heart bypass patients, and eventually, even bioengineered organ transplants.
Breakley was diagnosed with end-stage kidney disease three years ago and has been receiving hemodialysis treatments ever since, where his blood is filtered, cleaned and returned to his body. He first visited Duke University Hospital two years ago when he started experiencing problems with his veins. That’s when he met Dr. Jeffrey Lawson, a vascular surgeon and professor of surgery at Duke.
Kidney hemodialysis patients like Breakley sometimes require an artery to be connected to a vein to speed blood flow during treatments, according to Duke Medicine.
But Breakley’s Teflon graft, which was implanted a few years ago and is composed of artificial materials, stopped working during dialysis treatments. The graft was implanted in the lower part of his arm.
“It subsequently became infected, which happens to a lot of foreign materials,” Lawson said. “Like a car mechanic, if you’re a dialysis patient, you need to know a vascular surgeon.”
Lawson explained to him that surgically implanting a bioengineered vein created from human cells would lower the risk for clogging and infection.
From the start, Breakley understood he would be the first person in the U.S. to receive the new vein. And last Wednesday, his surgery was a success in the eyes of the researchers and surgeons who’ve worked on the new medical technology since the beginning.
Breakley said he’s watched younger patients visit the clinic and receive kidney dialysis alongside him, and this is a chance for him to help that generation.
“I feel good because I know I’m doing something to try and help society,” Breakley said.
A team of Duke post-doctorate students, faculty and surgeons continue to work on the bioengineered vein project. A few went one step further to form Humacyte, a biomaterials engineering company that moved its headquarters to Research Triangle Park in 2008. Twenty-six people work for the company.
Shannon Dahl is one of its co-founders and pursued her doctorate at Duke University. She has worked on the bioengineered vein project since 1999.
Now, the project has reached the first stage of clinical trials in human patients, and she said the surgery was an exciting breakthrough.
Clinical tests with human patients began in Poland in December. Lawson said Polish surgeons were trained at Duke, and he flew to Poland to serve as a consultant in the operating room during the implantation of the first few grafts.
“They’ve done very well, performed just as well as we could hope,” Lawson said.
The U.S. Food and Drug Administration recently approved a phase-one trial involving 20 kidney dialysis patients in the U.S., according to Duke Medicine. Duke researchers enrolled the first U.S. patient – Breakley.
Breakley will have regular post-operation checkups with doctors and surgeons.
“It was like my child graduated from high school,” Dahl said of the vein project, “but it was also like the first day of kindergarten at the same time.”
Within Humacyte’s labs, tubular scaffolds with human cells are stored in bioreactors, where a nutrient solution is pumped like blood through the bioengineered vein. The cells absorb nutrients for two months, allowing tissue to grow into the scaffold’s shape.
Right next to the bioreactor, a small tank of solution sloshes around in a clear bag. This solution then washes the cells away, cleansing the vein in a process that takes days and removes any chance that the vein will be rejected by the patient’s body. What’s left is a collagen tube, which is the same material that makes up a person’s skin and cartilage.
“Patients who need grafts often get synthetic grafts, and those are prone to failure mechanisms,” Dahl said.
But these veins were created with smooth muscle cells from donated aortas, the largest artery in the body. In pre-clinical tests, the bioengineered blood vessel performed better than other synthetic and animal-based implants, according to Duke Medicine.
Once the bioengineered vein is implanted, the patient’s own cells begin to take over and cover the implant.
“It goes from being a tube we made to your tube, because it’s made now from your cells and it’s living in your body as part of you,” Lawson said.
The bioengineered veins can be stored in the fridge for a year, making the technology commercial and off-the-shelf, Dahl said. Humacyte is currently preparing for an increase in demand, and Duke doctors hope these implants will some day be used not only in kidney dialysis patients, but in those who need heart bypass surgery as well. And looking long-term into the future of tissue engineering, Dahl said, is the creation of organs for patients needing transplants.
“It’s amazing, you know, the things that technology can do,” Breakley said, just days after his surgery. “At the rate they’re going, eventually there won’t be any part of the body that they won’t be able to give them.”