June 13, 2012 -- Scientists in Sweden are reporting a medical first: a vein grown in a lab for a 10-year-old girl using her body's own cells.
Doctors are hailing the step as a milestone in tissue engineering, a field in which doctors grow windpipes, bladders, lungs and other organs to replace faulty ones while avoiding the dangerous, lifelong complications of organ transplants.
While a handful of doctors around the world have had success growing blood vessels and other organs and transplanting them into patients, doctors said this is the first time a vein has been lab-grown and successfully transplanted using cells and parts taken entirely from the human body.
"To many of us working in this field, it is a validation of what we believe will be a revolution in medicine," said Dr. Adam Katz, director of plastic surgery research at the University of Florida.
Suchitra Sumitran-Holgersson, one of the authors of a report on the transplant published today in the Lancet journal, said the experimental procedure could someday bring promise to patients needing new blood vessels for dialysis or coronary bypasses.
"It is very difficult to find suitable arteries and veins to use for these patients," she said. "It would be good to create a personalized artery and vein for them."
Sumitran-Holersson and her colleagues grew the vein for a 10-year-old girl who had a blockage in the vein connecting her intestines and spleen with her liver. The rare condition can cause life-threatening bleeding, delayed development and even death. The patients often need a graft of a vein to replace the blocked one.
But traditional vein grafts are complicated. Doctors usually cut deep into patients' legs or necks to harvest their own veins to replace defective ones elsewhere, putting the patients at risk of an additional, traumatic surgery. Another option is using man-made vessels as replacements, but those are prone to dangerous clots and blockages and virtually guarantee that the patient will need a lifelong course of drugs to keep their immune system from attacking the vessel.
In this new approach, doctors took about 3.5 inches of a vein from the groin of a 30-year-old deceased donor and, in the lab, scraped away all of the donor's cells, leaving just the protein scaffolding of the vein. Doctors then took cells from the bone marrow of the 10-year-old girl and seeded the vein scaffolding with them. Then, for two weeks, they waited for the cells to grow.
The result was a blood vessel engineered entirely from human tissue. When surgeons took the vein and used it to replace the faulty vein leading to the girl's liver, normal blood flow was restored almost immediately, the researchers said.
The vessel had to be repaired after nine months when hardened scar tissue in the girl's body put too much pressure on the transplanted vessel.
A year after the transplant, the girl has grown nearly 2.5 inches, gained 11 pounds and has even taken up light gymnastics. So far, her body also shows no signs that it will reject the vein. But doctors will have to make sure that the vein and the liver stay healthy.
"When we met her last week, she was somersaulting and talking away," Sumitran-Holgersson said. "So far, she is doing very well."
The vein graft was a riff on a technique being put into action by scientists around the world to get around typical problems of organ transplantation. In 2008, European researchers stripped cells from a donated wind pipe and seeded it with a patient's own cells before transplanting it into a 30-year-old woman. In 2010, scientists at Massachusetts General Hospital did the same thing with a donated pair of lungs. A team at Wake Forest School of Medicine used a biodegradable mold smeared with bladder cells to grow bladders for a group of children in the 1990s.
Dr. Christopher Breuer, an associate professor of surgery at Yale School of Medicine, has also worked on growing blood vessels using a synthetic vessel skeleton lined with patients' bone marrow cells. He said the Swedish team will need to do more experiments to prove that their vessels are durable enough to replace high-pressure vessels close to the heart and to withstand the rigors of dialysis. But he said their achievement is a major step forward.
"The fact they were able to do this safely on a patient is fantastic," Breuer said.
Even though the results are exciting, doctors remain cautious about their implications for patients who need vein grafts for more common conditions, such as dialysis or coronary bypasses. The process of harvesting a donor's vein and covering it with the girl's own cells was nearly as complicated and costly as the process for an organ transplant.
"The organization and resources required for this process are significant and would severely limit the applicability of the treatment strategy to large groups of patients," said Dr. William Marston, chief of vascular surgery at University of North Carolina Hospitals.
Some cardiovascular surgeons said many patients having coronary bypasses have no shortage of their own arteries and veins that can be used in those surgeries. And many patients can't wait for treatment while doctors grow a vein for them.
Also, the fact that the graft needed repair after a year is a concern.
"A uniform conduit such as a perfectly sized and available bioengineered vein would be of great utility, but it needs to last closer to a lifetime, not a year," said Dr. John Calhoon, a professor of head and thoracic surgery at the University of Texas Health Science Center.
Sumitran-Holgersson said more work will need to be done to work out the kinks in the process and to test it in other patients. But she remains optimistic about scientists' ability to create personalized blood vessels and other organs, reducing the need for a lifetime of drugs and surgeries.
"This is a very exciting technique and one that can greatly improve a patient's quality of life after transplantation," she said. "I think we're going to see quite a bit of this in the future."