Bioengineered Blood Vessels Successfully Implanted In Patient

Brett Smith for – Your Universe Online

Surgeons at Duke University have announced the successful implantation of a bioengineered blood vessel in the United States.

“This is a pioneering event in medicine,” said Dr. Jeffrey H. Lawson, a vascular surgeon and vascular biologist at Duke Medicine who helped develop the technology. “It´s exciting to see something you´ve worked on for so long become a reality.”

“We talk about translational technology — developing ideas from the laboratory to clinical practice — and this only happens where there is the multi-disciplinary support and collaboration to cultivate it,” he added.

The Duke team is not the first-ever to perform the operation as clinical trials for bioengineered veins began in Poland in December. The Food and Drug Administration (FDA) recently agreed to allow a phase 1 trial involving 20 kidney dialysis patients in the United States. The concept of bioengineering veins came alive in 2011 when an East Carolina University team announced they successfully grew a bioengineered blood vessel.

Trials are initially set for easily accessible sites in hemodialysis patients, but researchers ultimately aim to develop a similar technique for heart bypass surgeries, which are performed nearly 400,000 times annually in the United States. “We hope this sets the groundwork for how these things can be grown, how they can incorporate into the host, and how they can avoid being rejected immunologically,” Lawson said. “A blood vessel is really an organ — it´s complex tissue. We start with this, and one day we may be able to engineer a liver or a kidney or an eye.”

Dr. Laura Niklason, a former faculty member at Duke and co-founder of medical spin-off company called Humacyte, began working on the technology in animal models as a post-doctoral student and eventually worked to develop the technology for humans.

“The bioengineered blood vessel technology is a new paradigm in tissue engineering,” Niklason said. “The fact that these vessels contain no living cells enables simple storage onsite at hospitals, making them the first off-the-shelf engineered grafts that have transitioned into clinical evaluation.”

The surgeons start the process with a biodegradable mesh that serves as a scaffolding for the vein. After the mesh is seeded with smooth muscle cells, it gradually dissolves as the cells grow in a medium of various nutrients. After a couple of months, a life-like vein is produced.

An earlier technique involved using the patient´s cells to seed the scaffolding and prevent their own body from rejecting the implant. However, that process was too time consuming, ruling out the possibility of mass production.

The refined technique uses donated human tissue to seed the blood vessel matrix. The resulting vein is washed with a special solution to rinse out any cells that might trigger an immune response. “At the end of the process, we have a non-living, immunologically silent graft that can be stored on the shelf and used in patients whenever they need it,” Niklason said. “Unlike other synthetic replacements made of Teflon or Dacron, which tend to be stiff, our blood vessels mechanically match the arteries and veins they are being sewn to. We think this is an advantage.”

When the novel vessels are placed into animals, they actually adopt the cellular properties of a blood vessel, eventually becoming indistinguishable from the tissue around it. “They are functionally alive,” Lawson said. “We won´t know until we test it if it works this way in humans, but we know from the animal models that the blood travels through the blood vessels and they have the natural properties that keep the blood cells healthy.”

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