First came bladders. Then pulmonary arteries. Followed by urethras, arteriovenous shunts and tracheas. Now, in another first for the world of tissue-engineered body parts, Swedish surgeons have successfully transplanted a bioengineered vein into a 10-year-old girl suffering from portal vein obstruction.
“This is a very good start for demonstrating what impact regenerative medicine can have on patients by using a biological matrix and seeding it with a patient’s own cells,” says Juliana Blum, cofounder and senior director of business operations at Humacyte, a North Carolina–based company developing bioengineered blood vessels for dialysis patients.
A team led by Suchitra Sumitran-Holgersson at the University of Gothenburg took a 9 centimeter-long snippet of vein from the groin of a deceased donor, stripped it of all cells and then reseeded the resulting hollow tube with stem cells taken from the recipient’s own bone marrow. Two weeks later, the surgeons transplanted the engineered conduit into the young girl. She remained healthy for close to a year, although a second procedure was then needed to lengthen the first graft after the vein started to constrict. Ever since the second transplant, in February of this year, the girl’s energy levels have improved and the blood flow to her kidneys are back to normal.
“The girl is somersaulting now,” says Sumitran-Holgersson, who reported the findings today in The Lancet. “Her parents told me, ‘We have a completely different child.’”
Ordinarily, when adults suffer the same problem as the girl who received the tissue-engineered blood vessel—a condition in which the vein that carries blood from the spleen and intestines to the liver is blocked—surgeons opt to transplant a patient’s own vein from the leg. But this option is not feasible for young children because of the potential growth problems that can result from grafting in a still maturing body.
Christopher Breuer, a pediatric surgeon at the Yale University School of Medicine in New Haven, Connecticut, says the study represents an important next step for tissue-engineered technology. “This is a new application,” he notes. “This is the first time a bioengineered vein has been used in the portal circulation.”
As researchers try to make these procedures more routine, however, the use of stem cells on bioengineered grafts could face regulatory delays. “Whether real or not, regulatory agencies consider the risk of tumorogenesis or alterations in DNA a serious problem,” says Todd McAllister, cofounder and chief executive of Cytograft Tissue Engineering, a Novato, California company developing tissue-engineered blood vessels for people on dialysis for end-stage kidney disease.
Breuer, for one, is trying to overcome those obstacles. He is leading the first clinical trial in the US testing a tissue-engineered vascular product: a bioengineered blood vessel for children with a congenital heart defect. For more on his approach, see our 2011 news feature, ‘Taking tissue engineering to heart’.
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